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8.2: The Flower and the Fruit - Biology

8.2: The Flower and the Fruit - Biology


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The Flower

A flowercompact generative shoot with sterile, male and female zones, specifically in that order, other flower terms see in the separate glossary in the text (Figure (PageIndex{3})) is a compact generative shoot that is comprised of three zones: sterile (perianth), male (androecium), and female (gynoecium) (Figure (PageIndex{2})). Perianth is typically split into green part (calyx, consists of sepals) and color part (corolla, consists of petals). Sometimes perianth consists of similar parts which are neither sepals nor petals: tepals. This might be seen in the tulip (Tulipa) flower where tepals change their color from green (like in calyx) to red, white or yellow (like in corolla).

The general characters that a flower has are sex, merosity, symmetry, and the position of the gynoecium. Merosity is simply the number of parts in each whorl of a plant structure, whether it is the number of sepals, petals in a corolla, or the number of stamens. The position of the gynoecium refers to whether the ovary is superior or inferior (Figure (PageIndex{6})). Inferior ovary (cucumber, Cucumis, apple Malus or banana Musa) will develop into a fruit where stalk and remnants of perianth are on the opposite ends, whereas superior ovary will make fruit where stalk is placed together with perianth (like in tomatoes, Solanum). More terms are described in the following separate small glossary:

FLOWER PARTS occur in whorls in the following order—sepals, petals, stamens, pistils.

(The only exceptions are flowers of Eupomatia with stamens then perianth, Lacandonia with pistils then stamens, and some monocots like Triglochin, where stamens in several whorls connect with tepals.)

PEDICEL flower stem

RECEPTACLE base of flower where other parts attach

HYPANTHIUM cup-shaped receptacle (Figure (PageIndex{2}))

PERIANTH = CALYX + COROLLA

SEPALS small and green, collectively called the CALYX, formula: K

PETALS often large and showy, collectively called the COROLLA, formula: C

TEPALS used when sepals and petals are not distinguishable, they form SIMPLE PERIANTH, formula: P

ANDROECIUM collective term for stamens: formula: A

STAMEN = FILAMENT + ANTHER

ANTHER structure containing pollen grains

FILAMENT structure connecting anther to receptacle

GYNOECIUM collective term for pistils/carpels, formula: G. Gynoecium can be composed of:

  1. A single CARPEL = simple PISTIL, this is MONOMERY

  2. Two or more fused CARPELS = compound PISTIL, this is SYNCARPY

  3. Two or more unfused CARPELS = two or more simple PISTILS, this is APOCARPY

(Note that variant #4, several compound pistils, does not exist in nature.)

To determine the number of CARPELS in a compound PISTIL, count LOCULES, points of placentation, number of STYLES, STIGMA and OVARY lobes.

Figure (PageIndex{3}) Most important parts of the flower.

PISTIL Collective term for carpel(s). The terms CARPEL and PISTIL are equivalent when there is no fusion, if fusion occurs then you have 2 or more CARPELS united into one PISTIL.

CARPEL structure enclosing ovules, may correspond with locules or placentas

OVARY basal position of pistil where OVULES are located. The ovary develops into the fruit; OVULES develop into seeds after fertilization.

LOCULE chamber containg OVULES

PLACENTA place of attachment of OVULE(S) within ovary

STIGMA receptive surface for pollen

STYLE structure connecting ovary and stigma

FLOWER Floral unit with sterile, male and female zones

ACTINOMORPHIC FLOWER A flower having multiple planes of symmetry, formula: (ast)

ZYGOMORPHIC FLOWER A flower having only one plane of symmetry, formula: (uparrow)

PERFECT FLOWER A flower having both sexes

MALE / FEMALE FLOWER A flower having one sex, formula: ♂ / ♀ (Figure (PageIndex{5}))

MONOECIOUS PLANTS A plant with unisexual flowers with both sexes on the same plant

DIOECIOUS PLANTS A plant with unisexual flowers with one sex on each plant, in effect, male and female plants

SUPERIOR OVARY most of the flower is attached below the ovary, formula: (G_{underline{dots}})

INFERIOR OVARY most of the flower is attached on the top of ovary, formula: (G_{overline{dots}})

(Inferior ovary only corresponds with monomeric or syncarpous flowers.)

WHORL flower parts attached to one node

Flower formula and diagram

Since there are so many terms about flowers, and at the same time, flower structure and diversity always were of immense importance in botany, two specific ways were developed to make flower description more compact. First is a flower formula. This is an approach where every part of flower is designated with a specific letter, numbers of parts with digits, and some other features (whorls, fusion, position) with other signs:

(ast K_{4}C_{4}A_{2+4}G_{underline{(2)}}): flower actinomorphic, with four sepals, four petals and six stamens in two whorls, ovary superior, with two fused carpels

(uparrow K_{(5)}[C_{(1,2,2)}A_{2,2}]G_{underline{(2 imes2)}}): flower zygomorphic, with five fused sepals, five unequal fused petals, two-paired stamens attached to petals, superior ovary with two subdivided carpels

(ast K_{(5)}C_{(5)}[A_{5}G_{underline{(3)}}]): actinomorphic flower with five fused sepals and five fused petals, five stamens attached to pistil, ovary inferior, with three fused carpels

The following signs are used to enrich formulas:

PLUS “+” is used to show different whorls; minus “(-)” shows variation; “(vee)” = “or

BRACKETS “[]” and “()” show fusion

COMMA “,” shows inequality of flower parts in one whorl

MULTIPLICATION “( imes)” shows splitting

INFINITY “(infty)” shows indefinite number of more than 12 parts

Flower diagram is a graphical way of flower description. This diagram is a kind of cross-section of the flower. Frequently, the structure of pistil is not shown on the diagram. Also, diagrams sometimes contain signs for the description of main stem (axis) and flower-related leaf (bract). The best way to show how to draw diagram is also graphical (Figure (PageIndex{7})); formula of the flower shown there is (ast K_{5}C_{5}A_{5}G_{underline{(5)}}).

ABC model

All parts of flower have a specific genetic developmental origin explained in the ABC model (Figure (PageIndex{8})). There are three classes of genes with expression which overlaps as concentric rings, and these genes determine which cells develop into particular organ of the flower. If there are A and C genes expressed, cells will make sepals and pistils. In areas where A and B are active, petals will form; areas where B and C are active are the sites where stamens will appear. A will make a sepal, C will “create” a carpel:

  • A alone ( ightarrow) calyx

  • A + B ( ightarrow) corolla

  • C + B ( ightarrow) androecium

  • C alone ( ightarrow) gynoecium

Origin of flower

An example of a primitive magnoliid flower would be Archaefructus which is a fossil water plant from the lower Cretaceous time period in China. Its fructifications (flower units, FU) were very primitive and did not yet form a compacted flower, instead, there were multiple free carpels, and paired stamens (Figure (PageIndex{9})).

Another ancestral flowering plant is Amborella,a small forest shrub of New Caledonia (Figure (PageIndex{10})), which is an island in the Pacific Ocean.

Amborella has irregular flowers, a stylar canal, unusual 5-celled embryo sacs that have one central cell, and only four other cells (egg cell and its “sisters”). A stylar canal is a canal that leads to the ovary that the pollen tubes pass through so these plants are not completely “angiospermic”, this represents one of the stages of the origin of pistil (Figure (PageIndex{11})).

The Inflorescence

Inflorescence is an isolated generative shoot (shoot bearing FU). Together, inflorescences make generative shoot system. Its diverse structure is of not lesser importance than the structure of vegetative shoot system.

The vast diversity of inflorescences can be split into four groups, or “models” (Figure (PageIndex{12})). Sole flower is sometimes considered as a “Model 0”.

Two models are most widespread. Model I inflorescences are based on the racemebasic monopodially branched inflorescence (Model I) (monopodially branched generative shoot). They are simple or double and mostly monopodial (Figure (PageIndex{14})).

Model II inflorescences (Figure (PageIndex{13})) bear or consist of closed (sympodially branched) units. The most complete but more rare variant is thyrsus, whereas reduced variants (monochasia and dichasia) are more frequent.

Pollination

Pollination could be of two types: self- and cross-pollination. Cross-pollination can happen in both abiotic and biotic ways. Abiotic would be represented by gravity, wind, or water; biotic would be performed by agents like insects, birds, bats, or in some cases tree mammals like possums. Wind-pollination is seen as being wasteful and unintelligent due to the fact that the plant needs to produce so much more pollen without any precise targeting.

Adaptation to the particular pollination agent results in different pollination syndromes. For example, cup-shaped flowers are usually pollinated with massive animals like beetles and even bats. Funnel-shaped flowers as well as labiate flowers (with lips), are adapted to flies and bees. Flowers with long spurs attract butterflies and birds (like hummingbirds or sugarbirds).

Self-pollination often exists like a “plan B”, in case cross-pollination is, for some reason, impossible. Sometimes, self-pollinated flowers even do not open; these flowers are called cleistogamous.

If pollination needs to be avoided, apomixis will prevent it. Apomixis requires reproductive organs, but there is no fertilization. One type of apomixis is apospory when an embryo develops from the maternal diploid tissue when an embryo develops from the maternal diploid tissue, but does not go through the meiosis stage. In this process, asexual reproduction will have become vegetative. Another type of apomixis would be apogamy (parthenogenesis) when embryo develops from an unfertilized gamete after diploidization has occurred. Here, vegetative reproduction evolved from sexual reproduction.

The Fruit

A fruit is defined as ripened ovary, flower, or whole inflorescence. The origins of the fruit coat and the pericarp (Figure (PageIndex{15})) which is comprised of the exocarp, mesocarp, and endocarp, are mostly from the wall of the pistil.

Fruits can be simple, multiple, or compound. *Simple fruitssimple fruitfruit originated mostly from one pistil come from a single pistil (like cherry, Prunus). *Multiple fruitsmultiple fruitfruit originated from many pistils are formed from many pistils of the same flower (strawberry, Fragaria). A compound fruitfruit originated from the whole inflorescence: infrutescence (infructescense) would be a pineapple (Ananas) or fig (Ficus) which comes from multiple flowers (inflorescence).

Fruits can be dry or fleshy. An example of dry fruit is a nut like peanut (Arachis) or walnut (Juglans). Examples of fleshy fruits include apples (Malus) or oranges (Citrus).

Fruits also delegate dispersal function to their different parts. *Dehiscent fruitsdehiscentfruits which open (like canola, Brassica) open and delegate dispersal to individual seeds.

Indehiscent fruits (like papaya, Carica) will not open and will be dispersal units (diaspores) themselves.

Schizocarp fruits (like in spurge, Euphorbia or maple, Acer) are in between: they do not open but break into several parts, and each of them contains one seed inside. For example, maple fruit consists of two “wings”, each of them contains the part of fruit and one seed.

In addition, simple fruits could be monomerous (1-seeded) like nut or achene (sunflower, Helianthus), or bear multiple seeds (like follicle in tulip, Tulipa).

All these different variants have their own names partly described in the following table:

TypeConsistencyOpeningExample(s)
SimpleFleshyIndehiscentDrupe, Berry, Hesperidium, Pome
SimpleDryDehiscentCapsule, Legume (pod), Silique (Figure 8.3.1)
SimpleDrySchizocarpicRegma, Samara, Shizocarp
SimpleDryIndehiscentCaryopsis (grain), Nut (incl. acorn), Achene
MultipleFleshyIndehiscentMultiple drupe
MultipleDryDehiscentFollicle
MultipleDryIndehiscentMultiple nut
CompoundFleshyIndehiscentCompound berry
CompoundDryIndehiscentCompound nut

Fruit anatomy

Fruit anatomy is the plant anatomy of the internal structure of fruit. [1] [2] Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggregate fruits are formed from a single compound flower and contain many ovaries or fruitlets. [3] Examples include raspberries and blackberries. Multiple fruits are formed from the fused ovaries of multiple flowers or inflorescence. [3] Examples include fig, mulberry, and pineapple. [3]

Simple fruits are formed from a single ovary and may contain one or many seeds. They can be either fleshy or dry. In fleshy fruit, during development, the pericarp and other accessory structures become the fleshy portion of the fruit. [4] The types of fleshy fruits are berries, pomes, and drupes.

In some fruits, the edible portion is not derived from the ovary, but rather from the aril, such as the mangosteen or pomegranate, and the pineapple from which tissues of the flower and stem provide food. The grains of grasses are single-seed simple fruits wherein the pericarp (ovary wall) and seed coat are fused into one layer. This type of fruit is called a caryopsis. Examples include cereal grains, such as wheat, barley, and rice.


8.2: The Flower and the Fruit - Biology

The separation in time of the male and female phases has led most observers to believe that a vector or "pollinator" is needed to move pollen from one flower to another. The European honey bee is the commonly used pollinator. The data from the pollinizer project suggests that the spatial placement of pollinizers may be critical due to the foraging behavior of the honey bee since most honey bees tend to forage in a relatively small radius of 1 to 4 trees.

We have been monitoring honey bee activity on avocado during the last year and have compared the efficiency of two honey bee races (Italian and New World Carniolan). We monitored the percent of the honey bees visiting avocado flowers during the day. Figure 8. Show a honey bee visiting a male phase ‘Ettinger’ flower. We used the presence of perseitol, a sugar unique to avocado, to assay for honey bee visitation. The drop in the middle of the day approximates the time when the female and male flower phases are in transition (Figure 9).

Interesting data has been generated by this project. During the current year we are continuing collaboration with other researchers in Florida and Israel. We hope to further elucidate the mechanism by which pollen is transferred from male to female flowers as well to understand the role of the honey bee. This information will assist growers in making informed decisions regarding the subject of pollination.


6 Major Types of Inflorescence (With Diagrams) | Botany

The following points highlight the six major types of inflorescence. After reading this article you will learn about: 1. Racemose Inflorescence 2. Cymose Inflorescence 3. Compound 4. Cyathium 5. Verticillaster 6. Hypanthodium.

Inflorescence: Type # 1. Racemose Inflorescence:

In this type of inflorescence the main axis does not end in a flower, but it grows continuously and develops flowers on its lateral sides in acropetal succession (i.e., the lower or outer flowers are older than the upper or inner ones). The various forms of racemose inflorescence may be described under three heads.

(i) With the main axis elongated, i.e., (a) raceme (b) spike (c) spikelets (d) catkin and (e) spadix.

(ii) With the main axis shortened, i.e., (i) corymb and (ii) umbel.

(iii) With the main axis flattened, i.e., capitulum or head.

(i) Main Axis Elongated:

In such cases the main axis remains elongated and it bears laterally a number of stalked flowers. The lower or older flowers possess longer stalks than the upper or younger ones, e.g., radish (Raphanus sativus), mustard (Brassica campestris), etc.

When the main axis of raceme is branched and the lateral branches bear the flowers, the inflorescence is known as compound raceme or panicle, e.g., neem (Azadirachta indica), gul-mohar (Delonix regia), etc.

The main axis of the inflorescence together with the latest axes, if present, is termed as the peduncle. The stalk of the individual flower of the inflorescence is called the pedicel.

In this type of racemose inflorescence the main axis remains elongated and the lower flowers are older, i.e., opening earlier than the upper ones, as found in raceme, but here the flowers are sessile, i.e., without pedicel or stalk, e.g., amaranth (Amaranthus spp.), latjira (Achyranthes aspera), etc.

Each spikelet may bear one to several flowers (florets) attached to a central stalk known as rachilla. Spikeletes are arranged in a spike inflorescence which is composed of several to many spikelets which are combined in various manners on a main axis called the rachis. Some are in compound spikes (i.e., in wheat—Triticum aestivum), others are in racemes (e.g., in Festuca), while some are in panicles (e.g., in Avena).

The usual structure of spikelet is as— There is a pair of sterile glumes at the base of spikelet, the lower, outer glume called the first, and the upper, inner one called the second. Just above the glumes, there is series of florets, partly enclosed by them.

Each floret has at its base a lemma and palea. The lemma is the lower, outer bract of the floret. Usually the lemma also known as inferior palea bears a long awn as an extension of the mid-rib at the apex or back.

The floral parts borne in the axil of lemma. The palea (also known as superior palea) often with two longitudinal ridges (keels or nerves), stands between the lemma and the rachilla. Flowers and glumes are arranged on the spikelet in two opposite rows. Spikeletes are characteristic of Poaceae (Gramineae) or Grass family, e.g., grasses, wheat, barley, oats, sorghum, sugarcane, bamboo, etc.

This is a modified spike with a long and drooping axis bearing unisexual flowers, e.g., mulberry (Moras alba), birch (Betula spp.), oak (Quercus spp.), etc.

This is also a modification of spike inflorescence having a fleshy axis, which remains enclosed by one or more large, often brightly coloured bracts, the spathes, e.g., in members of Araceae, Musaceae and Palmaceae. This inflorescence is found only in monocotyledonous plants.

(ii) Main Axis Shortened:

In this inflorescence the main axis remains comparatively short and the lower flowers possess much longer stalks or pedicels than the upper ones so that all the flowers are brought more or less to the same level, e.g., in candytuft (Iberis amara).

In this inflorescence the primary axis remains comparatively short, and it bears at its tip a group of flowers which possess pedicels or stalks of more or less equal lengths so that the flowers are seen to spread out from a common point. In this inflorescence a whorl of bracts forming an involucre is always present, and each individual flower develops from the axil of a bract.

Generally the umbel is branched and is known as umbel of umbels (compound umbel), and the branches bear flowers, e.g., in coriander (Coriandrum sativum), fennel, carrot, etc. Sometimes, the umbel is un-branched and known as simple umbel, e.g., Brahmi (Centella asiatica). This inflorescence (umbel) is characteristic of Apiaceae (Umbelliferae) family.

(iii) Main Axis Flattened:

In this type of inflorescence the main axis or receptacle becomes suppressed, and almost flat, and the flowers (also known as florets) are sessile (without stalk) so that they become crowded together on the flat surface of the receptacle. The florets are arranged in a centripetal manner on the receptacle, i.e., the outer flowers are older and open earlier than the inner ones.

The individual flowers (florets) are bracteate. In addition the whole inflorescence remains surrounded by a series of bracts arranged in two or three whorls.

The flowers (florets) are usually of two kinds:

(i) Ray florets (marginal strap-shaped flowers) and

(ii) Disc florets (central tubular flowers).

The capitulum (head) may also consist of only one kind of florets, e.g., only tubular florets in Ageratum or only ray or strap-shaped florets in Sonchus. A capitulum or head is characteristic of Asteraceae (Compositae) family, e.g., sunflower (Helianthus annuus), marigold (Tagetes indica), safflower (Carthamus tinctorius). Zinnia, Cosmos, Tridax, Vernonia, etc. Besides, it is also found in Acacia and sensitive plant (Mimosa pudica) of Mimosaceae family.

The capitulum inflorescence has been considered to be the most perfect. The reasons are as follows:

The individual flowers are quite small and massed together in heads, and therefore, they add to greater conspicuousness to attract the insects and flies for pollination.

At the same time there is a considerable saving of material in the construction of the corolla and other floral parts.

A single insect may pollinate flowers in a short time without flying from one flower to another.

Inflorescence: Type # 2. Cymose Inflorescence:

In this type of inflorescence the growth of the main axis is ceased by the development of a flower at its apex, and the lateral axis which develops the terminal flower also culminates in a flower and its growth is also ceased. The flowers may be pedicellate (stalked) or sessile (without stalk).

Here the flowers develop in basipetal succession, i.e., the terminal flower is the oldest and the lateral ones younger. This type of opening of flowers is known as centrifugal.

The cymose inflorescence may be of four main types:

(i) Uniparous or monochasial cyme

(ii) Biparous or dichasial cyme

(iii) Multiparous or polychasial cyme and

(i) Uniparous or Monochasial Cyme:

Here the main axis ends in a flower and it produces only one lateral branch at a time ending in a flower. The lateral and succeeding branches again produce only one branch at a time like the primary one.

There are three forms of uniparous cyme:

(a) Helicoid Cyme:

When the lateral axes develop successively on the same side, forming a sort of helix, the cymose inflorescence is known as helicoid or one-sided cyme, e.g., in Begonia, Juncus, Hemerocallis and some members of Solanaceae.

(b) Scorpioid Cyme:

When the lateral branches develop on alternate sides, forming a zigzag, the cymose inflorescence is known as scorpioid or alternate-sided cyme, e.g., in Gossypium (cotton), Drosera (sundew), Heliotropium, Freesia, etc.

(c) Symopodial Cyme:

Sometimes, in monocha­sial or uniparous cyme successive axes may be at first curved or zig-zag (as in scorpioid cyme) but later on it becomes straight due to rapid growth, thus forming a central or pseudoaxis. This type of inflorescence is known as sympodial cyme as found in some members of Solanaceae (e.g., Solanum nigrum).

(ii) Biparous or Dichasial Cyme:

In this type of inflorescence the peduncle bears a terminal flower and stops growing. At the same time the peduncle produces two lateral younger flowers or two lateral branches each of which terminates in a flower.

There are three flowers the oldest one is in the centre. The lateral and succeeding branches in their turn behave in the same manner, e.g., jasmine, teak, Ixora, Saponaria, etc. This is also known as true cyme or compound dichasium.

(iii) Multiparous or Polychasial Cyme:

In this type of cymose inflorescence the main axis culminates in a flower, and at the same time it again produces a number of lateral flowers around. The oldest flower is in the centre and ends the main floral axis (peduncle). This is a simple polychasium.

The whole inflorescence looks like an umbel, but is readily distinguished from the latter by the opening of the middle flower first, e.g., Ak (Calotropis procera), Hamelia patens, etc.

(iv) Cymose Capitulum:

This type of inflorescence is found in Acacia, Mimosa and Albizzia. In such cases the peduncle is reduced or condensed to a circular disc. It bears sessile or sub-sessile flowers on it. The oldest flowers develop in the centre and youngest towards the periphery of the disc, such arrangement is known as centrifugal. The flowers make a globose head, which is also called glomerule.

Inflorescence: Type # 3. Compound Inflorescence:

In this type of inflorescence the main axis (peduncle) branches repeatedly once or twice in racemose or cymose manner. In the former case it becomes a compound raceme and in the latter case it becomes a compound cymose inflorescence.

The main types of compound inflorescence are as follows:

1. Compound Raceme or Panicle:

In this case the raceme is branched, and the branches bear flowers in a racemose manner, e.g., Delonix regia, Azadirachta indica, Clematis buchaniana, Cassia fistula, etc.

Also known as umbel of umbels. Here the peduncle (main axis) is short and bears many branches which arise in an umbellate cluster. Each such branch bears a group of flowers in an umbellate manner. Usually a whorl of leafy bracts is found at the base of branches and also at the bases of flowers arranged in umbellate way.

The former whorl of bracts is called involucre and the latter involucel. Typical examples of compound umbel are—Daucus carota (carrot), Foeniculum vulgare (fennel), Coriandrum sativum (coriander), etc.

Also known as corymb of corymbs. Here the main axis (peduncle) branches in a corymbose manner and each branch bears flowers arranged in corymbs. Typical example-cauliflower.

Also known as spike of spikelets. The typical examples are found in Poaceae (Gramineae) family such as-wheat, barley, sorghum, oats, etc. This type has already been described under sub-head spikelets.

Also known as spadix of spadices. Here the main axis (peduncle) remains branched in a racemose manner and each branch bears sessile and unisexual flowers. The whole branched structure remains covered by a single spathe. The examples are common in Palmaceae (Palmae) family.

Also known as head of heads or capitulum of capitula. In this case many small heads form a large head. The typical example is globe thistle (Echinops). In this plant the heads are small and one-flowered and are arranged together forming a big compound head.

Inflorescence: Type # 4 . Cyathium:

This type of inflorescence is found in genus Euphorbia of family Euphorbiaceae also found in genus Pedilanthus of the family. In this inflorescence there is a cup-shaped involucre, often provided with nectar secreting glands. The involucre encloses a single female flower, represented by a pistil, in the centre, situated on a long stalk.

This female flower remains surrounded by a number of male flowers arranged centrifugally. Each male flower is reduced to a solitary stalked stamen. It is evident that each stamen is a single male flower from the facts that it is articulated to a stalk and that it possesses a scaly bract at the base. The examples can be seen in poinsettia (Euphorbia), Pedilanthus, etc.

Inflorescence: Type # 5 . Verticillaster:

This type of inflorescence is a condensed form of dichasial (biparous) cyme with a cluster of sessile or sub-sessile flowers in the axil of a leaf, forming a false whorl of flowers at the node. The first of main floral axis gives rise to two lateral branches and these branches and the succeeding branches bear only one branch each on alternate sides.

The type of inflorescence is characteristic of Lamiaceae (Labiatae) family. Typical examples, are—Ocimum, Coleus, Mentha, Leucas, etc.


Types of fruit

There is a massive variety of different types of fruit. The main separation between fruit types is between fleshy and dry fruits. Fleshy fruits have a juicy layer of tissue in the pericarp, seen in fruits such as oranges, tomatoes and grapes whereas dry fruits do not.

Fleshy fruits can be further separated into a large number of fruit types. Common types of fleshy fruits include berries, pomes, drupes and hesperidia fruits. Berries are fruits with one or many seeds and a thin layer of skin e.g. grapes, tomatoes and blueberries. Pomes includes fruits that are made from a swollen receptacle rather than a swollen ovary such as apples and pears. Drupes are fruits that have a single seed that is protected by a hard shell – commonly known as stone fruit. Citrus fruits are classed as hesperidia fruits because of their leathery skins that produce scented oils.

Many plants, such as maples, beans, oaks and sunflowers, produce dry fruit that don’t have a fleshy layer to their pericarp. Dry fruit can be either dehiscent, where they pop open and release their seeds to the world or indehiscent, where they do not pop open. Examples of dry dehiscent fruits include legumes, orchid fruits, milkweed plants and magnolias and examples of dry indehiscent fruit that do not pop open include carrots, acorns, grass grains and chestnuts.

Fruit can also be separated into simple, aggregate and multiple fruits. Simple fruits are made from one flower and one ovary and includes the majority of fruits. In fact, all of the examples of fruits given in this article up until this point are simple fruits. Aggregate fruits are formed from one flower that has several ovaries and each of them develops into fruit segments. These include fruits such as blackberries and raspberries. Multiple fruits are formed when multiple flowers produce fruits that merge to create one larger piece of fruit. This is seen in pineapples and figs.


Chapter 8 : Flowers and Fruit

Night length is measured using a protein : phytochrome which has two forms :
Pr ( absorbs red light ) and Pfr ( absorbs far red light ).

After pollination, the seed develops inside a fruit. Fruit is made of three layers: the exocarp is the outer layer. The mesocarp forms the fleshy tissue in the middle and the endocarp surrounds the seed.

Types of fruit

Drupe - has fleshy fruit and a single seed with a hard endocarp eg peaches, coconut and olives

Berry - has many seeds eg tomatoes, peppers and cucumber but not strawberries !

Aggregate fruit - develop from one flower with many pistils eg strawberries.

Legumes - split along two sides eg beans, peas

Capsules - are dry fruit that have several carpels eg orchids

Nuts - have one seed and a hard pericarp eg acorns

Grains - have the fruit and seed joined closely together eg wheat, rice, barley.

Multiple fruits - come from several different flowers joined together eg pineapples.


Flower: Important Parts and its Anatomy | Botany

The flower consists of an axis, also known as receptacle and lateral appendages. The appendages are known as floral parts or floral organs. They are sterile and reproductive. The sepals and petals which constitute the calyx and corolla respectively are the sterile parts. The stamens and the carpels are the reproductive parts. The stamens compose the androecium, whereas the free or united carpels compose the gynoecium.

The vegetative shoot shows unlimited growth, whereas the flower shows the limited growth. In flower, the apical meristem ceases to be active after the formation of floral parts. In more specialized flowers there is a shorter growth period and they produce a small and more definite number of floral parts than the more primitive flowers.

In still more advance flowers there are specialized characters, such as, whorled arrangement of parts instead of spiral, adnation of parts of two or more different whorls, cohesion of parts within a whorl, zygomorphic instead of actinomorphic condition, and epigynous condition instead of hypogynous condition.

Important Parts of a Flower:

The sepals resemble leaves in their anatomy. Each sepal consists of ground parenchyma, a branched vascular system and an epidermis. The chloroplasts are found in the green sepals but usually there is no differentiation in the palisade and spongy parenchyma. They may contain crystal—containing cells, laticifers, tannin cells and other idioblasts. The epidermis of sepals may possess stomata and trichomes.

The traces are similar in origin and number. From the evidence of vascular system, sepals are clearly, in nearly every case morphologically bracts—that is, and they have been derived directly from leaves and are not sterile sporophylls.

The petals also resemble leaves in their internal structure. They contain ground parenchyma, a more or less branched vascular system, and an epidermis. They may also contain crystal containing cells, tannin cells, laticifers and certain other idioblasts. They contain pigments—containing chromoplasts.

Very often, the epidermal cells of the petals contain volatile oils which emit the characteristic fragrance of the flowers. In certain flowers the anticlinal epidermal walls of the petals are wavy or internally ridged, whereas the outer walls may be convex or papillate. The epidermis may also possess stomata and trichomes.

Commonly the stamen consists of a two-lobed four-loculed anther. The anther is found to be situated on a slender filament which bears single vascular bundle. In certain primitive dicotyledonous families the stamens are leaf-like and possess three veins, whereas in advance types they are single-veined.

The structure of filament is simple. The vascular bundle is amphicribral and remains surrounded by parenchyma. The epidermis is cutinized and bears trichomes. The stomata may also be present on the epidermis of both anther and filament. The vascular bundle is found throughout the filament and culminates blindly in the connective tissue situated in between the two anther- lobes.

The outermost wall of the anther is the epidermis. Just beneath the epidermis there is endothecium which usually possesses strips or ridges of secondary wall material mainly on those walls which do not remain in contact with the epidermis. The innermost layer is composed of multinucleate cells this is nutritive in function and known as tapetum.

The wall layers which are located in between the endothecium and tapetum are often destroyed during the development of the pollen sacs. On the maturation of the pollen the tapetum disintegrates and the outer wall of the pollen sac now consists of only the epidermis and endothecium. At the time of dehiscence of the anthers the pollen are released out through stomium.

The unit of gynoecium is called the carpel. A flower may possess one carpel or more than one. If two or more carpels are present they may be united or free from one another. When the carpels are united the gynoecium is known as syncarpous when they are free the gynoecium is said to be apocarpous. A gynoecium with single carpel is also classified as apocarpous.

The apocarpous gynoecium is termed simple pistil, whereas the syncarpous gynoecium is termed compound pistil. The carpel is commonly interpreted as foliar structure. The carpel of an apocarpous or syncarpous gynoecium is being differentiated into the ovary and the style. The upper part of the style is differentiated as a stigma. The stigma is sessile.

The ovary consists of the ovary wall, the locule or locules and in a multilocular ovary, the partitions. The ovules are found to be situated on the inner or adaxial (ventral) side of the ovary wall. The ovule-bearing region forms the placenta. According to Puri (1952) the position of the placentae is related to the method of union of carpels.

In a carpel the placenta occurs close to the margin. Since there are two margins, the placenta is double in nature. The two halves may be united or separate. The number of double placenta in compound ovaries is equal to number of carpels. When the carpels are folded, the ovary is multilocular and the placentae occur in the centre of the ovary where the margins of the carpels meet.

This is axile placentation. When the partitions of the ovary disappear, it becomes free-central placentation. When the carpels are joined margin to margin and the placentae are found to be situated on the ovary placentation is parietal.

Most commonly the carpels has three veins, one dorsal or median and two ventral or lateral, and the vascular supply of the ovules has been derived from the ventral bundles. The vascular bundles of the ovary, possessing axile placentation appear in the center of the ovary, with the phloem turned inward and the xylem wall, the outward.

The ovary and style are composed of epidermis, ground tissue of parenchyma, and vascular bundles. The outer epidermis is cuticularized and may have stomata. The ovule consists of a nucellus which encircles the sporogenous tissue. There are two integuments of epidermal origin, and a stalk, funiculus. The ovule consists of parenchyma and contains a more or less dominant vascular system.

Vascular Anatomy of Floral Parts of Flower:

The study of the vascular anatomy has helped in solving many intricate problems of floral morphology. It has shown that many structures are not what they appear to be or what they are commonly taken to be. The fundamental vascular plan remains more or less unaltered and can always be of some help (Puri, 1952).

Morphologically the flower is a determined shoot with appendages, and these appendages are homologous with leaves. This commonly accepted view is sustained by the anatomy of the flowers. Flowers, in their vascular skeletons, differ in no essential way from leaf stems.

They are often more complex than most stems. Taxonomy and comparative morphology have in large measure determined the structural nature of the flower. Anatomy of the flower has aided in the solution of certain puzzling conditions.

The Pedicel and the receptacle have typical structure, with a normal vascular cylinder. The cylinder may be unbroken or it may contain a ring of vascular bundles. In the region where floral organs are borne, the pedicel expands into the receptacle.

The vascular cylinder also expands and the vascular bundles increase somewhat in number, and finally traces begin to diverge. In the simplest cases vascular traces for different organs and whorls of organs arise quite independently (e.g., in Aquilegia). In other cases various degrees of fusion may take place between bundles situated more or less in the same sectors.

The appendage traces are derived from the receptacular stele exactly as leaf traces are derived in typical stems. When the floral organs are numerous and closely placed the gap of traces break the receptacular stele into a meshwork.

The sepals are with very few exceptions, anatomically like the leaves of the plant in question. A sepal usually receives three traces derived from the same or different sources. As regards the morphological nature of the sepals, they have often been considered as equivalent to bracts and foliage leaves.

Such a view is born out by a study of vascular anatomy which reveals practically the same vascular pattern as exists in foliage leaves and bracts of the same plant.

In their vascular supply the petals are sometimes leaf like, but much more often they are like stamens. The petals may have one, three or several traces. Very commonly there is but one trace. The petals appear to be sometimes modified leaves, like the sepals, but in the great majority of families they are sterile stamens.

However, since stamens are the homologous of the leaves, it is not always possible to determine from anatomical evidence along whether one trace petals in certain families are modified stamens or whether they have come more directly from leaf-like structures.

A stamen generally receives a single trace which remains almost un-branched throughout its course in the filament. In the anther region it may undergo some branching. In a few Ranalian families and rarely elsewhere as in some members of the Lauraceae and Musaceae, three traces are present in each stamen. In Ravenala (Musaceae) each filament is traversed by 25 to 28 small vascular bundles.

Most of these disappear as the anther is approached, and the system of central bundles consisting of three or four bundles, continues into the connective. From other evidence the above mentioned families appear to be fairly primitive, it seems highly probable that the single trace condition is one of reduction from three.

In the simple flower of Aquilegia the stamens traces pass off, one to each organ in several whorls. Above the supermost whorl of stamens the vascular cylinder becomes complete again.

The carpel is commonly looked upon as a leaf-like organ folded upward, i.e., ventrally with its margins more or less completely fused and bearing the ovules. This conception has been supported by the anatomy. The details of origin, number and course of the bundles forming the vascular supply are exactly like those of leaves the carpel has one, three, five or several traces.

The three trace carpel is most common. The five-trace carpel is nearly as common as the three traces, and carpels with seven, nine and more traces are increasingly less and less common. The evidence that the one-trace carpel (nearly always an achene) has been derived by reduction from the three-trace type.

The median trace which leaves the stele below the other carpel traces is known as the dorsal trace because it becomes the dorsal (midrib) bundle of the folded organ. The outermost traces are known as ventral or marginal traces because they become the bundles that run along the ventral edge of the carpel, i.e., along or near the margins of the organ if it were unfolded.

The upward and inward folding of the sides of the carpel brings about the inversion of these ventral bundles. The phloem remains on the ventral side in the carpel, whereas it is on the dorsal side in the midrib (dorsal) bundle. This important condition may be easily understood when it is remembered that the carpel is leaf-like, with its margins folded upward. The ovule traces are derived from the ventral bundles.

When floral parts are fused, the vascular bundles of these parts may also be fused. If carpels are united, the lateral bundles, either those of the same carpel or those of two adjacent carpel, may be fused in pairs.

The fusion in the vascular tissue of a carpel may be present in the ventral bundles from an origin as one trace throughout their length, or may exist only in part of the carpel where the ventral bundles arise as separate traces, they may unite at any point in their course.

In syncarpy there are fusion changes similar to those in free carpels. The lines that separate the carpels and their margins have been disorganised. The inverted ventral bundles form a ring of bundles in the centre. These bundles usually lie in pairs. Here each pair consists of the ventral bundles, of the same carpel, or more often of bundles from each of two adjacent carpels.

In the centre of a three carpellary syncarpous ovary there may be a ring of six or three ventral bundles. If the ring consists of three bundles, each bundle is morphologically double and represents either the two ventral traces of one carpel or one from one carpel and one from the adjacent carpel.

Several workers proposed that the evolutionary changes in the structure of the gynoecium of the flower of angiosperms involve various manners of union of carpels of the same flower.

In such angiospermous flower the carpel may become joined by their margins to the receptacle (Fig. 44.6 B), or they may grow together laterally in a closed folded condition (Fig. 44.6 C), or they may become laterally united in an open folded condition (Fig. 44.6. A).

The junction of carpels in an open condition may result in a unilocular ovary showing parietal placentation as shown in fig. 44.6 A. Folding combined with union of carpels with each other may form an ovary with as many locules as there are carpels. In such cases the ovules are borne on the central column of tissue where the carpels come together showing, axile placentation (Fig. 44.6 B, C).

The inferior ovary is formed by the adnation of the sepals, petals and stamens to the carpels or by the sinking of the gynoecium in a hollowed receptacle with fusion of the receptacle walls about the carpels. The vascular system is thought to show this structure in that the bundles found in the appendages of different whorls are variously fused but all show the usual orientation of xylem and phloem.

In certain flowers with inferior ovary (e.g., Calycanthaceae, Santalaceae and Juglandaceae) there is evidence that the ovary is partially enclosed in hollowed receptacle. Here the vascular bundles are prolonged from the axis to the level below the insertion of floral parts, other than the carpels, where traces to the parts diverge.

The main bundles continue farther from the periphery in a downward direction with a corresponding inversely oriented position of the xylem and the phloem. These bundles at lower levels give branches to the carpels. This type of orientation of the vascular system is thought to be the result of the invagination of the receptacular axis.


Types of fruits

The concept of “fruit” is based on such an odd mixture of practical and theoretical considerations that it accommodates cases in which one flower gives rise to several fruits (larkspur) as well as cases in which several flowers cooperate in producing one fruit (mulberry). Pea and bean plants, exemplifying the simplest situation, show in each flower a single pistil (female structure), traditionally thought of as a megasporophyll or carpel. The carpel is believed to be the evolutionary product of an originally leaflike organ bearing ovules along its margin. This organ was somehow folded along the median line, with a meeting and coalescing of the margins of each half, the result being a miniature closed but hollow pod with one row of ovules along the suture. In many members of the rose and buttercup families, each flower contains a number of similar single-carpelled pistils, separate and distinct, which together represent what is known as an apocarpous gynoecium. In other cases, two to several carpels (still thought of as megasporophylls, although perhaps not always justifiably) are assumed to have fused to produce a single compound gynoecium (pistil), whose basal part, or ovary, may be uniloculate (with one cavity) or pluriloculate (with several compartments), depending on the method of carpel fusion.

Most fruits develop from a single pistil. A fruit resulting from the apocarpous gynoecium (several pistils) of a single flower may be referred to as an aggregate fruit. A multiple fruit represents the gynoecia of several flowers. When additional flower parts, such as the stem axis or floral tube, are retained or participate in fruit formation, as in the apple or strawberry, an accessory fruit results.

Certain plants, mostly cultivated varieties, spontaneously produce fruits in the absence of pollination and fertilization such natural parthenocarpy leads to seedless fruits such as bananas, oranges, grapes, and cucumbers. Since 1934, seedless fruits of tomato, cucumber, peppers, holly, and others have been obtained for commercial use by administering plant growth substances, such as indoleacetic acid, indolebutyric acid, naphthalene acetic acid, and β-naphthoxyacetic acid, to the ovaries in flowers (induced parthenocarpy).

Classification systems for mature fruits take into account the number of carpels constituting the original ovary, dehiscence (opening) versus indehiscence, and dryness versus fleshiness. The properties of the ripened ovary wall, or pericarp, which may develop entirely or in part into fleshy, fibrous, or stony tissue, are important. Often three distinct pericarp layers can be identified: the outer (exocarp), the middle (mesocarp), and the inner (endocarp). All purely morphological systems (i.e., classification schemes based on structural features) are artificial. They ignore the fact that fruits can be understood only functionally and dynamically.

Classification of fruits
structure
major types one carpel two or more carpels
dry dehiscent follicle—at maturity, the carpel splits down one side, usually the ventral suture milkweed, columbine, peony, larkspur, marsh marigold capsule—from compound ovary, seeds shed in various ways—e.g., through holes (Papaver—poppies) or longitudinal slits (California poppy) or by means of a lid (pimpernel) flower axis participates in Iris snapdragons, violets, lilies, and many plant families
legume—dehisces along both dorsal and ventral sutures, forming two valves most members of the pea family silique—from bicarpellate, compound, superior ovary pericarp separates as two halves, leaving persistent central septum with seed or seeds attached dollar plant, mustard, cabbage, rock cress, wall flower
silicle—a short silique shepherd's purse, pepper grass
dry indehiscent peanut fruit—(nontypical legume) nut—like the achene (see below) derived from 2 or more carpels, pericarp hard or stony hazelnut, acorn, chestnut, basswood
lomentum—a legume fragmentizing transversely into single-seeded "mericarps" sensitive plant (Mimosa) schizocarp—collectively, the product of a compound ovary fragmentizing at maturity into a number of one-seeded "mericarps" maple, mallows, members of the mint family (Lamiaceae or Labiatae), geraniums, carrots, dills, fennels
achene—small single-seeded fruit, pericarp relatively thin seed free in cavity except for its funicular attachment buttercup, anemones, buckwheat, crowfoot, water plantain
cypsela—achenelike, but from inferior compound ovary members of the aster family (Asteraceae or Compositae), sunflowers
samara—a winged achene elm, ash, tree-of-heaven, wafer ash
caryopsis—achenelike from compound ovary seed coat fused with pericarp grass family (Poaceae or Graminae)
fleshy (pericarp partly or wholly fleshy or fibrous) drupe—mesocarp fleshy, endocarp hard and stony usually single-seeded plum, peach, almond, cherry, olive, coconut
berry—both mesocarp and endocarp fleshy one-seeded: nutmeg, date one carpel, several seeds: baneberry, may apple, barberry, Oregon grape more carpels, several seeds: grape, tomato, potato, asparagus
pepo—berry with hard rind squash, cucumber, pumpkin, watermelon
hesperidium—berry with leathery rind orange, grapefruit, lemon
structure
major types two or more carpels of the same flower plus stem axis or floral tube carpels from several flowers plus stem axis or floral tube plus accessory parts
fleshy (pericarp partly or wholly fleshy or fibrous) pome—accessory fruit from compound inferior ovary only central part of fruit represents pericarp, with fleshy exocarp and mesocarp and cartilaginous or stony endocarp ("core") apple, pear, quince, hawthorn, mountain ash multiple fruits—fig (a "syconium"), mulberry, osage orange, pineapple, flowering dogwood
inferior berry—blueberry
aggregate fleshy fruits—strawberry (achenes borne on fleshy receptacle) blackberry, raspberry (collection of drupelets) magnolia

There are two broad categories of fruits: fleshy fruits, in which the pericarp and accessory parts develop into succulent tissues, as in eggplants, oranges, and strawberries and dry fruits, in which the entire pericarp becomes dry at maturity. Fleshy fruits include (1) the berries, such as tomatoes, blueberries, and cherries, in which the entire pericarp and the accessory parts are succulent tissue, (2) aggregate fruits, such as blackberries and strawberries, which form from a single flower with many pistils, each of which develops into fruitlets, and (3) multiple fruits, such as pineapples and mulberries, which develop from the mature ovaries of an entire inflorescence. Dry fruits include the legumes, cereal grains, capsulate fruits, and nuts.


Fruit and It&rsquos Types (Explained With Examples)

It is not easy to define a fruit. For a common man fruit means a sweet, juicy or pulpy, coloured, aromatic structure that encloses seed(s).

Botanically, a fruit develops from a ripe ovary or any floral parts on the basis of floral parts they develop, fruits may be true or false.

A true fruit or eucarp is a mature or ripened ovary, developed after fertilization, e.g., Mango, Maize, Grape etc. (Fig. 7.1 – A).

A false fruit or pseudo-carp is derived from the floral parts other than ovary, e.g., peduncle in cashew-nut, thalamus in apple, pear, gourd and cucumber fused perianth in mulberry and calyx in Dillenia (Or. Ou). Jack fruit and pine apple are also false fruits as they develop from the entire inflorescence. False fruits are also called spurious or accessory fruits (Fig. 7.1.-B).

(iii) Parthenocarpic fruits:

These are seedless fruits that are formed without fertilization, e.g., Banana. Now a day many seedless grapes, oranges and water melones are being developed by horticulturists. Pomology is a branch of horticulture that deals with the study of fruits and their cultivation.

Morphology of a Typical Fruit:

A fruit consists of pericarp and seeds. Seeds are fertilized and ripened ovules. The pericarp develops from the ovary wall and may be dry or fleshy. When fleshy, pericarp is differentiated into outer epicarp, middle mesocarp and inner endocarp.

Types of Fruits:

On the basis of the above mentioned features, fruits are usually classified into three main groups:

(3) Composite or Multiple fruits.

1. Simple Fruits:

When a single fruit develops from a single ovary of a single flower, it is called a simple fruit. The ovary may belong to a monocarpellary simple gynoecium or to a polycarpellary syncarpous gynoecium. There are two categories of simple fruits—dry and fleshy.

Simple fruits are of two types:

These fruits are not fleshy, and their pericarp (fruit wall) is not distinguished into three layers.

2. Succulent Fruits (Fleshy fruits):

In these fruits pericarp is distinguished into epicarp, mesocarp and endocarp. Mesocarp is fleshy or fibrous. These fruits are indehiscent, and seeds are liberated after the decay of the flesh.

Three types of dry fruits are distinguishable:

(A) Dehiscent Fruits (Capsular Fruits):

Characteristic of these fruits is that their pericarp rupture after ripening and the seeds are disseminated.

(B) Indehiscent Fruits (Achenial Fruits):

As their name indicates, pericarp of such fruits does not rupture on ripening and the seeds remain inside.

(C) Schizocarpic Fruits (Splitting Fruits):

These fruits fall in between the above-mentioned two categories. Here, the fruit on ripening divides into one-seeded segments or mericarp but the mericarps remain un-ruptured.

(A) Dehiscent Fruits (Capsular Fruits) (Fig. 7.2):

Depending on the mode of dehiscence, these fruits can be divided into the following five classes:

Legume develops from a superior, monocarpellary, unilocular ovary. At maturity, the fruit dehisces along both the sutures i.e. ventral as well as dorsal. It is characteristic of family Leguminosae (Pea, Gram etc).

It is similar to legume but it dehisces only along the ventral suture, e.g. Larkspur, Calatropis, Michelia, Vinca.

Siliqua develops from a bicarpellary, syncarpous, superior ovary which is unilocular but becomes bilocular due to a false septum called replum. It is an elongated fruit in which dehiscence occurs along both the sutures from base to apex and the seeds attached to the replum get exposed. Example-Brassica (Mustard).

A short and flattened siliqua is called silicula. It is almost as broad as long. Examples: Iberis amara (Candytuft), Capsella bursa-pastoris (Shepherd’s purse).

It is a simple dry many seeded dehiscent fruit developing from a multi-carpellary syncarpous ovary.

On the basis of dehiscence capsules are of the following types:

The dehiscence occurs through pores as in Poppy (Papaver) (Fig. 7.3.-A).

This is a special name given to a capsule when the dehiscence is transverse so that the top comes off as a lid as if exposing a box of seeds, e.g., Celosia (Cock’s comb), Amaranth us, Chalfweed (fig. 7.3-B).

(iii) Loculicidal:

The dehiscence occurs by longitudinal slits which open into the loculi, e.g., 1 dy’s finger (Abelmoschus) (Fig. 7.3-C).

The dehiscence line appears along the septa, e.g.. Linseed, Cotton (Fig. 7.3D) to the central axis ,eg. Datura (Fig. 7.3-E).

Tin- broken parts separate exposing the seeds attached to the central axis, e.g Datum (Fig. 7.3-E)

(B) Indehiscent or Achenial Fruits:

Achenial fruits are simple, indehiscent, single seeded having a thin, dry, woody or leathery pericarp.

There are five common types of achenial fruits:

The pericarp of the fruit is free from the testa of the seed. The seed is attached to the pericarp only at one point. It develops from superior monocarpellary pistill having unilocular and uniovuled ovary, e.g., Mirabilis jalapa, but more commonly achenes occur in the form of aggregate fruits as in Ranunculus and Clematis etc.

It is similar to achene except that in this case pericarp and testa are inseparably fused as in cereals. It is a characteristic future of family Gramineae. Example—Wheat, Maize etc.

11 is a characteristic feature of family Compositae. The fruit wall is free from testa and a typical feature of the fruit is the presence of a pappus having a crown of hair like processes which helps in wind-dispersal. The fruit develops from bicarpellary, syncarpous, interior ovary having a single basal ovule, e.g., Sonchus, Dandelion etc.

It develops from a monocarpellary pistil with a superior, unilocular and uniovuled ovary. The pericarp is expanded in the form of wings which help in dispersal. Example—Holoptelea and Elm (Fig. 7.4.-D).

The pericarp is harder and leathery or woody. It may develop from a simple or compound pistil with superior or inferior, uniovuled ovary. Examples—Quercus (Oak), Litchi and Cashew-nut Trapa etc. (Fig. 7.5). In case of Litchi pericarp is hard and leathery. The edible part is aril which is an outgrowth of testa from the micropylar end and becomes juicy

(C) Schizocarpic or Splitting Fruits:

These fruits maybe considered intermediate between achenial (being indehiscent) and capsular (being many seeded) fruits. The fruit breaks up into a number of indehiscent single-seeded segments called mericarps from which seeds are liberated only when pericarp gets rotten. In some cases one- seeded parts of the fruit are dehiscent and are called Cocci.

Schizocarpic fruits are of following 5 types:

The fruit is constricted between the seeds and usually breaks up into segments containing one or more seeds, e.g. Mimosa, Acacia arabica (Fig. 7.6). In case of radish, the fruit is lomentaceous siliqua.

This is a type of two or more-chambered fruit derived from a syncarpous (i.e., compound) ovary. The pericarp is extended in the form of wings and at maturity the fruit breaks up % into single seeded mericarps. e.g., EIm (Holoptelea), maple (Fig. 7.7).

This is a two-seeded fruit derived from bicarpellary, syncarpous, inferior, bilocular and uniovuled ovary. It is a typical fruit of family umbelliferae. The two mericarps split along the central axis or carpophore to which they remain attached. Persistent style and stylopodium are present e.g. Coriander. (Fig. 7.8).

This fruit is derived from superior, syncarpous pistil, multilocular with axile placentation. The fruit splits into many mericarps. e.g. Hollyhock (Althaea rosea), Salvia, Ocimum (Fig. 7.9).

It is derived from polycarpellary pistil which splits into as many Cocci (dehiscent segments) as there are carpels. Regma of castor breaks up into three cocci as it is derived from tricarpellary syncarpous pistil. Similarly, regma of Geranium breaks into five cocci as it is derived from five carpels (Fig. 7.10).

2. Succulent or Fleshy Fruits:

These are simple fruits with fleshy pericarp. The simple succulent fruits are of 3 types – drupe, pome and berrie.

The pericarp or fruit wall is differentiated into thin epicarp (skin) fleshy mesocarp and stony endocarp.Hence.it is also called as stone fruit, e.g., Mango, Coconut, Peach, Almond, Trapa etc. In mango, mesocarp is juicy and edible. In coconut mesocarp is fibrous and edible part is endocarp. In almond, epicarp and mesocarp get peeled off and only hard endocarp can be seen in marketed fruits. The edible part is cotyledons (Fig. 7.11).

It is a simple, fleshy but false fruit as it is surrounded by a fleshy thalamus which is edible while actual fruit lies within, e.g., apple, pear, loquat etc. (Fig. 7.12).

Berry is a fleshy fruit in which there is no hard part except the seeds (Fig. 7.13). Pericarp may be differentiated into epicarp, mesocarp and endocarp. One or other of these layers may form pulp in which seeds are embedded which generally gets detached from the placenta.

The fruits derived from superior ovary are called superior or true berries as in brinjal, grape, tomato. False berries are derived from inferior ovary and thalamus and pericarp are fused as in banana and guava etc. In case of bannana (Fig. 7.13C) epicarp and thalamus are peeled off, mesocarp and endocarp with embedded unripe seeds forms the edible part. In case of Date, epicarp and mesocarp are edible while papery and thin endocarp is thrown away along with the seed.

There are some fruits which show variations from the normal berry:

This develops from inferior ovary which is unilocular or falsely trilocular having parietal placentation. The seeds remain attached to placenta. The outer ring is very hard as in Cucurbits (Fig. 7.13D).

It develops from polycarpellary, syncarpous, superior, multilocuiar ovary with axile placentation. Epicarp forms the leathery peeling, mesocarp is in the form of fibres while the endocarp projects inwards forming distinct chambers from which juicy ingrowths in the form of hair arise which form the edible part, eg. Citrus (Orange, Lemon) (Fig. 7.13E).

It is derived from polycarpellary, syncarpous, multilocuiar and superior ovary. In this case, epicarp is woody. The placenta and inner layers of pericarp become pulpy and edible in which the seeds are scattered. The testa is muclilagenous, e.g., Aegle marmelose (Fig. 7.13-1).

It is a berry with an outer hard rind formed of epicarp and a part of mesocarp. The inward foldings of mesocarp form chambers. Each chamber is lined by papery endocarp which encloses a group of seeds. The seeds are covered by edible juicy testa. e.g., Pomranate (Fig. 7.13-G).

II. Aggregate Fruits:

Flowers with polycarpellary and apocarpous gynoecium give rise to a number of fruitlets as there are a number of free ovaries, each giving rise to one fruitlet. Sometimes, these fruitlets coalesce together appearing to be a single fruit but in many other cases, the fruitlets remain free from one another forming etaerio of fruitlets. An aggregate fruit is named according to the nature of fruitlets.

Aggregate of achenes are found in Fragaria (strawberry), Rose, Ranunculus, Nelumbium (lotus) etc. Here each fruitlet is an achene and achenes are hairy. In rose (Rosa), many achenes are present on a saucer (cup) – shaped thalamus. In lotus (Nelumbium), thalamus becomes spongy and some achenes are embedded in it. In strawberry [Fragaria), the thalamus is fleshy and becomes red on maturation and is the edible part (Fig. 7.14).

2. Etaerio of follicles:

Etaerio of follicles can be seen in Aconitum, Catotropis, Crypiostegia etc. In Aconitum three fruitlets from each flower while two fruitlets (follicles) develop from one flower in Calotroiis, Cryptostegia and Michelia (Fig. 7.15).

3. Etaerio of samaras (Fig. 7.16).

It can be studied in Ailanthus where many winged samaras develop from one flower.

In Artabotrys berries occur in a bunch. In Anona squomosa (Custard apple) the berries become very fleshy and being crowded together on a thick thalamus form a complex single fruit (Fig. 7.17). The apices of berries fuse together forming something like a common rind.

5. Etaerio of drupes (Fig. 7.18):

It is an aggregate of small drupes or drupelets developing from different carpels of a flower, and arranged collectively on fleshy thalamus, e.g. Rubus idaeus.

III. Composite Fruits:

A fruit developing from a complete inflorescence is called a multiple or a composite fruit.

There are two main types of composite fruits:

This type of fruit is found in Mulberry, Pineapple and Jack fruit (kathal). These fruits are derived from catkin, spike and spadix type of inflorescence (Fig. 7.19).

Mulberry (Morus indica) fruit develops from catkin in which fleshy perianth encloses dry achenes.

In jack fruit, thick club-shaped peduncle has the flowers arranged on it. The fertile fruits have juicy, edible perianth lobes and the bracts form more or less juicy chaffs around them. The spines on the tough rind represent the stigmas of the carpels. Each seed is covered by a membranous testa. In Pineapple (Ananas sativus), the ovaries are not so conspicuous, edible portion being formed by peduncle, perianth and bracts. Each polygonal area on the surface represents a flower. This fruit develops from an intercalary spike.

This fruit develops from the hypanthodium type of inflorescence and is characteristic of Ficus. In fig, Banyan etc. (Fig. 7.21) female flowers within the closed receptacle (which becomes fleshy) of the inflorescence develop into achenes giving rise to a multiple fruit of achenes.


Flower and early fruit development in a diploid strawberry, Fragaria vesca

The diploid woodland strawberry, Fragaria vesca, is being recognized as a model for the more complex octoploid commercial strawberry, Fragaria × ananassa. F. vesca exhibits a short seed to seed cycle, can be easily transformed by Agrobacteria, and a draft genome sequence has been published. These features, together with its similar flower structure, potentially make F. vesca a good model for studying the flower development of other members of the Rosaceae family, which contains many economically important fruit trees and ornamental plants. To propel F. vesca's role in genetic and genomic research and to facilitate the study of its reproductive development, we have investigated in detail F. vesca flower and early fruit development using a seventh generation inbred diploid line, Yellow Wonder 5AF7. We present here standardized developmental staging and detailed descriptions of morphological changes associated with flower and early fruit development based on images of hand dissected flowers, histological sections, and scanning electron microscopy. In situ hybridization with the F. vesca AGAMOUS homolog, FvAG, showed expression in young stamen and carpel primordia. This work lays the essential groundwork and standardization for future molecular, genetic, and genomic studies of F. vesca.


Watch the video: Ένζυμα - βιολογικοί καταλύτες (January 2023).