Morphological Characters of Flowers

The highly specialized shoot which is responsible for the production of fruits and seeds is called flower. Flowers are concerned with the sexual reproduction. Flower has following pans.

1.Sepals: Sepals are outermost green part of flower. They enclose the other floral part of the flower. Sepals are colleethely called calyx.Petals:

2.Petals are large coloured part or flower. Fhey form w horl just inside the sepals. Petals are collectively called corolla.

3. Stamens: Stamens are the imile organs of flower. rhey form whorl inside corolla. Stamens are collective Is called androecium.

4. Carpels: Carpels are female organs of flower. They are present in the centre of the flower. Carpels are collecti‘ely called gynoecium.

The calyx and corolla are collectively known as the perianth. In some flowers calyx and corolla cannot he differentiated. Thus term perianth is used. Generally perianth consists of a single whorl. If the leaves of the perianth are free:the perianth is called polyphyllous. If the leaves of perianth fused. it is called gamophyllous.

Number of floral parts

Mostly, flowers have four series of floral leaves. They form four whorls. In some cases, sonic flora The leaves are arranged in more than one whorl Therefore, they rime more than four whorls fork. floral leaves are arranged in twos. threes. knits or fives in each whorl. In some cases, the floral lea y es are arranged in the multiple of three or live. Thus flowers are called dimerous. tetramerous or pentamerous. Sonic flowers have more than ten floral leaves in each whorl. Such flowers are indefinite.

Flower a modified shoot

It is believed that flower is a modified shoot. It is supported by follow Mg facts:

    I. Flower arises in the axil of leaf (bract) like leafy shoot.

2. Flower has central axis (thalamus)^. like vegetative shoot. Thalamus has very short ink:modes. Floral leaves are crowded on it. The thalamus of some flowers like passion flower has elongated internodes. In some cases. the thalamus elongates after bearing floral leaves. It prokrit.:, upward and bears other foliage leaves. Thus it behaves as ordinary shoot.

3.    ‘Be internal structure ct thalamus resembles the internal structure of stem.the floral leaves t how     cyclic or whorled phyllotaxis like ordinary leaves.

4. The arrangement of the floral lea t es in flott er bud (aestivation) is similar to the arrangement of floral leaves in leaf bud.

5. ‘Hie structures and forms of sepals and petals resemble the foliage leaves. The sepals are mostlt green in colour like leaves. In sonic cases, petals are also green.

6. The stamens are petal I ike^.in some llott ers like rose. canna etc^.

7. The carpels are regarded as lea es. This lea t c has become folded along its margin to form closed

   Bract

   A special leaf in the axil of which flower borne is called bract. Bracts hate different sizes. colours forms etc. There are Wowing kinds of bracts:

   1.  Leafy bract: In this ease. bracts are green and leaf like. It occurs in most of the plants.

   2. Scaly bract: In this case. the bract is scale like. It is also called chaff. Example: sunflowers

   3. Petaloid: In this case, bract is coloured like petals Example:

   4. Houga invi idea.
   5. Spathe: This is a large bract. It encloses cluster of flowers. I:xample: Colocasia
   6. Involuere: It is a large bract present below a group or flowers. Example: sunflower.
   7. Cupule: It is a hard capsule like bract. It is formed b the Riskin of the bracts of involucres. Example: oak
   8. Glumes: These are small diA bracts. Example: wheat

Symmetry of flower

The symmetrical flowers can be devided into two equal halves by one

or more planes. Hie flowers ale di ided into three 1) pCS on the basis of their symmetry

1.  Actinomorphic or regular: If the flimer can be cut into to equal halve!: b more than one plane. it is called actinomorphic or regular .Example:popy
   
2.  Zygomorphic: If rite Ilinxer can he etit into two equal hakes old one plane. it is called /gomorphie or regular. Example: Ocimum
3. Asymmetrical: If the flower cannot be cut lino t“o equal ha I. es by any plane. it is called ass mmetrical. Example: Opuntia. lygornorphic and asymmetiie floi‘ers called irregular.

General descriptive terms of flower

1. Braeteate: Bract is present.

2. F.bracteate: Bract is absent

3. Pedieillate: Pedicle is present.

4. Sessile: Pedicle is absent.

5. Complete: Both calyx and corolla are present.

6. Incomplete: Either cal) x or corolla or both absent Flower is called monochalmydeous. if one of the calyx or corolla is absent. It May be apetahms or asepalous. If both cal\ x and corolla are assent. it is called aehalmydeous.

7. Perfect flower: A hermaphrodite or bisexual flower is called perfect flower. It has both stamens and carpels.

8. Imperfect flower: A unisexual flower is called imperfect flower. hi this case, either stamen or carpel is present. If only stamen is present, it is called staminate. If only^. carpel is present. it is called pistillate.

• Monoecious: If staminate and pistillate flowers occur on the same plant, the plant is called monoecious, e.g. castor oil plant (1,1).

• Dioecious: If staminate and pistillate flowers occur on the difkrent plants, the plant is called dioecious. e.g. date-palm GyveS)

• Polygamous: plant hears staminate. pistillate and hermaphrodite floskers. it is called polygamous. Example: mango.

• Neuter: If both stamens and carpels are absent, the plant is called neuter.

Thalamus

The terminal swollen_. part of the flower, which bears sepals, petals, stamens and carpels, is called thalamus. It is very short in most Ilmsers. Rut sometimes. it becomes %cry long. It has distinct nodes and internodes. The intemode beoxeen calyx and Corolla is called anthophore. The intemode bet corolla and androecium is called androphore. The internode between androeeium and gynoecium is called gynophore.

Insertion of floral leaves on thalamus

Thalamus has different forms. ^–Bert:fore. different flow,ers have three is pes of insertions:

I. Hypogynous: In this case. lhalailltiti is comex or conical. The

develops on the lop at thilaintt.. Rut stamens, petals and sepals are bore on the side ot pnoceitim. Oynoecium is superior but all other parts arc ndcrror. Example: Brassica. POPPY

2. Perigynous: In this case. thalamus is flattened or disc like. lie

gnoecium is present in the center of the disc. Rut the stamens. petals and sepals arc attached on the run of disc. In some cases. the gynoecium become; more or less cup like due to um% ard gro of its marOir camel do clops on the bottom of cup.In this case. gynoecium superior but all. other part, ire inferior.

3. Epigynous: In this ctise.^– the thalamus grows upt‘ard and surrounds the ovary. It fuses v4ith ovary. Therefore sepal. petals and stamens are inserted on the top of the ovary. Now gynoecium is inferior hut all other parts are superior. Examples: apple. pear etc.

Nectaries

The fleshy or glandular outgrowths borne in flowers are called nectaries. Neetaries secrete meet fluid called nectar. Example: Citrus. rose etc.

Floral parts Calyx

Calyx is the outermost whorl of the mer.It consists of sepals. here are follcming descriptive terms of calyx:Caducous: If the sepals fall oil as soon as the flower opens. it is called caducous. Example: pOppy.

2. Deciduous: If the sepals fall w hen the flover 6 niters. it is called

deciduous. Example: buttercup

2. Persistant: If the sepals remain in place eNen after the Fruit is lormed. it is called persistant. Example: pea. roses. cotton.

3. Petaloid: Ihe sepals are coloured like petals. Example: I .arkspur

4. Polysepalous: The sepak are free from one anther. Example: Brassiczt.

5. Gamosepalous: All sepals are united. structures:

• Tubular: Long and tube like.

• Iniiinidbuliforni I unnel shaped.

• Globose: Globe shaped

• Bilabiate: Forming mo lips

• Flooded: One or more sepal forms hood like structure.

• Spurred: One or more sepals form a long hollcos tube or spur.

Corolla

Corolla is the second %s hod of the Hower. It consists of petals. Corolla has tbllowing descriptke terms:

    I. Caducous: The petals WI off as soon as the firmer opens. Example: buttercup

2. Scpalokt: lithe corolla is sepal like.

3. Polypetalous: The petals are free from one anther. Example: l3rassica.

   (a) Clawed: Petals are nark’ al the base and expanded at :

• Cruciform (cross): The corolla consists of four clawed petals. These petals are arranged in the form of cross.. Example: Mustard family.

• Rosaceous: The petals are live in number. They have very short claws. Example: rose

• Caryophyllaceous: In this case, the calyx forms long tube. It consists of five petals. These petals have long claws. The limbs of petals spread out above the tube.

4. Gamopetalous: The petals are united with one anther. The number of teeth or lobes indicates the number of petals. It has following forms:

(a) Papilionaceous: In this ease, there are 5 clawed petals. These petals are not similar. They are found in pea

• Standard or Vesillum: It is the upper posterior petal. It is large and conspicuous.

• Wings: These are two lateral free petals.

• Keel or Carina: ^.These are two anterior most petals. ‘Fhey fuse to form a boat- shaped structure.

 

b) tubular: tube like

(c)campanulate:bell shaped

(d)infunidbuliform:funnel shaped

(e)globose:globe like

(f)rotate:wheel like

      (g)bilabiate:forms to lips

     (h)Spurred: Two or more petals united and form a long tube called spur.

         (i)Ligulate: The upper portion is long and strap like.

Aestivation

The arrangement of seppls and petals with respect to one anther in bud is called aestivation. “There are following t) pes of aestivations:

1. Open: The sepals mid petals do not meet at their ends.
2.  Valvate: The sepals and petals merely touch each other at their edges.
3.  Imbricate: The margins of the sepals and petals overlap each other

Corona

In some flowers, small outgrowths or ligules are developed in a circle on the corolla. Such outgrowths called

corona. The corona may be free or united.

Androecium

A miroecium is the collect e name of stamens. It limns third Vs horl of the flower. Stamen has two parts: filament and anther. Anther consists of two anther lobes. ‘these lobes are jointed by a band of connective tissues called connective. Each anther lobe has two longitudinal chambers called pollen sacs. Pollen grains are formed inside the pollen sacs. The ripened anther burst and releases the pollen grains. The side of anther containing connectives is called back and other side is called face. There are following descriptive terms of androecium:

I. Polyandrous: The stamens are free from each other. These stamens may he di. tetra or petandrous.

2. Ditlynamous: Stamens 4 in number. Two are short and two are long. All arc present in single whorl. Example: Ocimum

3. Tetradynamous: Stamens 6 in number. Four are long and two are short. They are present in ty,o hurls. Example: Brossito, radish.

4. Epipetalous: The slainewt used with the petals. Example potato
   

5. Antipetalous: Stamens opposite to the petals Example:zizyphus

5. Antisepalous: Stamen opposite to the petals.

6. Gynandrous: Stamens fused %s ill) the gynoecium.

7. Adelphous: Stamens united by their filaments. It may^. he monoaadelphous, diadelphous or polyadelphous. Example: Citrus. castor oil.

8. Synandrous: Stamens united by both filaments and anthers. Exaniple: gourds.

Attachment of Filaments to Anther

here are fbur types of attachments of filaments to anthers:

1.    Basithed or Innate: The filament is attached to the base of the anther. Example Brussica.
2.    Adnate: In this case, no joint is present between !he filament and the base of anther. The filament runs along whole length of the

3. Dorsifixed:attached to the back of the anther. The anther is immovable. Example: passion flower.

4. Versatile: The filament is attached to the back of anther and anther can swing on it. Example: Grasses

Gynoecium or Pistil

(Iynoecium or pistil forms the fourth whorl of the flower. It occupies the centre of the thalamus. It ma) consist of one or more carpels. ‘Riese carpels may remain free. Or they may fuse to form compound pistils. Each carpel has three pans: Ovary. style and stigma.

1. Ovary: It is the basal swollen portion of the carpel. It encloses one or more chambers or loculi. ‘these chambers have one or more ovules.

2. Style: It is slender stalk like structure. It arises front the top of ovary. It contains stylar tissues. Sometime, it is hollow. Its central canal is called sty tar canal.

3. Stigma: It is the top of the sty le. It receives the pollen grains. Evolution of carpel

It is believed that camel is modified foliage leaf.’llie leaf folded. Its two edges fused and met together. This line of union is called ventral suture. The opposite side is called dorsal suture. The broad lower portion of the folded leaf loons ovary. The elongated apex forms the style. The sty le slight sells to form stigma. Placenta develops along the ventral suture on the inner surface of wall of the mar. Ovules are attached to the placenta in two rows.

Descriptive terms ogynoecium

1. Monocarpellary: Gynoecium consists of single carpel. Example: pea

2. Bicarpellary: The gynoecium consists of two carpels. These carpels may be free or fused. Example: potato

3. Polycarpillary: The gynoecium consist man) free or fused carpels. Example: Citrus

4. Apocarpous: The gynoecitun has more than one free carpel.

Example: Buttercup

5. Syncarpous: The gynoecium consists of more than one fused carpels. These fused carpels form compound ovary. In some cases, only ovaries are united but stigmas are free like cotton. In some cases, ovary and styles are united like sunflowers. In some

Placentation

The cushion like ridges inside the ovary on which ovules arc attached is called placenta. The arrangement of placentas in the ovary is called placentation. There are different types of placentas:

1. Marginal: In this case, placenta is formed along the fused margins (ventral suture) of ovary. The gynoeci LIM is monocarpellary or poly carpillary and apocarpous. Examples: Cassia. etc.

2. Parietal: In this case. the ovary is conwound and unilocular. The fused margins of the carpels swell up to form placentas. Ovules attach on it. Sometimes. fused margins of the carpels grow inward to kurn incomplete septa. It divides each ovar into number of incomplete compartments. The ovules are borne on the surface of these septa like cucumber. In Brossicu, the placentation is parietal. It has bicarpellary ovary. This compohnd °van beconies hi ocular due to formation of false septum.

    

   

3. Axile: In this case, gynoecium is polywrioillary and syncarpOus. The fused margins of the carpels grow inward in the centre of ovary. ‘thus the compound ovary beam^–nes multilocular. The marginal placenta of all the carpels fuses in the centre to thrill a central nil. Ovtiles are :niched Am this central axis. Example: potato, Euphorbia. Sometimes, a number of false septa are formed. It increases the number of locale in the ovary.

4. Free central: In this case, the ovary is compound and ardlocular. The ovules are borne on a central axis arising from the base of the ovary. [hey are not attached on the fused margins. Example:

5. Basal: In this case, ovary is andocular. It has a single ovule attached to the base of the ovary. Example: Pol)gonum.

6. Superficial: In this case, ovule is borne on all inner margins of the carpels. Example: rush

7. Pendulous: In this case, each loculus of the o% my contains

single ovule. This value is attached on the top of the ovary. Example: fennel

  8. Ascending: In this case m ary is multilocular. Each loculus of the ovary contains single It is attached to the base.

Floral Diagram

The diagram representation of the arrangement of floral leaves on the mother axis of flower is called floral diagram. It is very. useful for the study of flimers. FolloYy ing procedure is adapted to form a floral diagram:

I. Drawing of planes: The axis on Y1. hich flower is borne is called

main axis or mother axis. The side of the flower towards the mother axis is posterior side. The side towards the bract or away from^– the mother axis is anterior side. A line drawn across the flower, passing through the mother axis and the centre of flower is called median plane. A line at right angles to this plane is called lateral plan. The lateral planes are called diagonal planes.

2. Representation of mother axis: Mother axis is indicated by a dot or small circle in the anterio-posterior plant above the diagram.

3. Odd sepal or odd petal: The limiter is looked from the above. The petal lying just opposite the mother axis is called odd sepal and odd petal. The number of petals and sepals are noted.

4. Representation of sepals and petals in diagram: Floral diagram is started from odd sepal or odd petal. ‘Elie exact numbers of petals and sepals are represented by brackets. The sepals are shown in the outer circle and petals are shown in the inner circle. Polysepalous and polypetalous condition is slims n by free ends of brackets. Gamopetalotts and gamosepalous condition is represented by linked brackets. In case of imbricate aestivation, the brackets are overlapped.

5. Representation of stamens: Stamens are represented by kidney shaped figures. In case of epipetalous condition, the stamens are lined with petals. In case of united filaments, the kidney figures are joined by circle.

6. Representation of gynoecium: Gynoecium is shoysn in the centre of the diagram. The ovary is drawn in double lines. Number of carpels is indicated by constrictions. The septa are slims n by radial lines. Ovule represented in the limn small rounded figure. They are attached with the placenta.

Types of floral diagrams

There are two types of floral diagrams:

(a) Empirical diagram: 1 he diagram in which only those parts of flowers are indicated %%Melt is actually present in a flower is called empirical diagram.

(b) Theoretical diagram: The diagram in which the parts originally present but now missing is indicated by dots is called theoretical diagram. For esample. lily diagram Slim\ plan of flowers of monocot plants. But ditThrent structures are missing in different members olmonocots. 1 hese parts are indicated by dots.

Floral Formula

The shor symbolic representation of the various parts of flower is called floral formula.

I. Sex of the flower:

gr or

Bisexual:

Unisexual male: ^‘6

Unisexual female:

2. Symmetery of flower Actinomorphic:

Zygomorphie:

2. Sepals

Calyx: K ,

Polysepalous: K number

Gamosepalous: K (n(1mber)

2. Petals Corolla:

Polypetalous: C »umber

Gamopetalous: C (number)

2. Perianth (if present) Perianth:

Polyphyllous: P number

Gamophyllous: P (number)

2. Stamens

Androecium: A

Androecium free: A number Androecium fused A (number)

Epipeta lous: CA

2. Carpels

Ci ynoecium: Ci

A pocarpous: C i number ,

Syncarpous: G (number)

Superior: Ci

Inferior Examples:

ioral formula of rose: , K₅C_S _ _a G

   Flora I formula of pea: t 9 K(5) C1+2+₍2₎ A ₍9₎+ 1 P1

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