· Flower is a highly modified and condensed shoot meant for sexual reproduction
· It is the characteristic of angiosperm
· The axis of the flower is called the peduncle or mother axis.
· The broad ended base of the flower, which lies at the tip of the pedicel is called the thalamus or receptacle.
· A complete flower consists of calyx, corolla, androecium, and gynoecium.

A. Unisexual flower (Incomplete flower)
· Only one sex is present in the flower that may be androecium or gynoecium.
· Pistillate flower – the presence of pistil or gynoecium only. e.g. Ray floret of Compositae (sunflower)
· Staminate flower – the presence of stamen only or androecium only. e.g. Pumpkin, Papaya

B. Bisexual flower:
· Androecium and gynoecium are present in the same flower. e.g Mustard, Pisum sativum
· Monoecious flower: Male and female flowers are borne on the same plant. e.g. Maize, colocassia, ficus, pinus
· Dioecious flower: Male and female flowers are found in separate plants. e.g. Papaya, Mulberry
· Polygamous flowers: Unisexual, bisexual and neutral flowers are born in the same plant. e.g. Mango, Polygonum

· Pedicellate and Sessile:
· The stalk of the flower is called a pedicel.
· A flower is Pedicellate if it has a stalk and is sessile if not stalked.
· Bracteate and Ebracteate:
· A leaf or leaf-like structure subtending a flower is called a bract.
· A flower that grows out from the axil of the bract is bracteate and that which does not have a bract is ebracteate.

C. Complete flower
· A flower having all the floral whorls, calyx, corolla, androecium and gynoecium. e.g. flower of Cruciferae, Solanaceae.

D. Incomplete flower
· If any one of the floral whorl (calyx, corolla, androecium and gynoecium) is missing the flower is incomplete. e.g. ray floret of compositae.

E. Cyclic
· Floral parts viz calyx, corolla, androecium and gynoecium are present in concentric circles. e.g. Cruciferae, malvaceae

F. Acyclic or Spiral
· Floral parts are arranged spirally. e.g. Magnoliaceae

G. Actinomorphic
· A flower that can be vertically divided into two equal halves by any vertical division passing through the centre.
· Such flowers are called radially symmetrical. E.g. Brassica

H. Zygomorphic
· A flower that can be divided into two equal halves in one plane only.
· Such flowers have bilateral symmetry.

I. Achlamydous
· A flower without perianth (sepals and petals) e.g. Euphorbia

· Pedicellate: A flower born on pedicel (stalk)
· Sessile: A flower lacking pedicel. e.g. Helianthus
· Neuter flower: A flower where both stamens and pistils are absent or functional. e.g. ray florets of Helianthus annuus (sunflower)
· Trimerous flower: Floral parts are in multiples of three. e.g. Asparagus
· Tetramerous: Floral parts are in multiples of four
· Pentamerous: Floral parts are in multiples of five
· Hypogynous: When the ovary is, superior and other parts are inferior. e.g. All except (compositae), i.e. cruciferae, solanaceae etc.
· Epigynous: Ovary is inferior. e.g. Compositae
· Perigynous: When the ovary is semi-superior. e.g. Rosaceae/ Rose, Pea gram
· Monochlamydous: Presence of one whorl (either calyx or corolla). e.g. Gramini, Liliaceae
· Dichlamydous: Presence of both whorls (calyx and corolla). e.g. all the family of dicots
· Anthophore: Internode between calyx and corolla. e.g. Silene
· Androphore: Internode between corolla and androecium. e.g. Gynandropsis, Passiflora
· Gynophore (gyne-female, phore-stalk): Internode between androecium and the gynoecium. e.g. Gynandropsis.
· Androgynophore: Presence of both androphore and gynophore. e.g. Gynandropsis

Various Parts of Flower

a. Calyx
· First and lowermost whorl of a flower which consists of several sepals.
· Individual unit is sepals
· Usually green (sepaloid) but sometimes coloured (petaloid)
· Polysepalous – Sepals may remain free from each other. e.g. Cruciferace
· Gamosepalous (Gamo= united) – sepals remain united to each other. E.g. Solanaceae
· The calyx modified into scale or pappus (in sunflower)
· Caducosus– sepals fall down after the opening of flowers. e.g poppy family
· Deciduous – sepals fall down after fertilization. e.g. Brassica, legume.
· Persistent– Sepals do not fall down after fertilization. e.g. Solanaceae

b. Corolla
· Second whorl of flower which consists of a number of the brightly coloured petals.
· Individual unit – petal
· Petals are brightly coloured and sometimes scented, and their function is to attract insects for pollination
· Sepaloid – petals green like sepals
· Petaloid - petals coloured other than green.
· Polypetalous – petals free. e.g Cruciferae, Malvaceae
· Gaemopetalous – petals fused. e.g Solanaceae
Shape of Corolla
(i) Cruciform
· Consists of four free petals (each differentiated into claw and a limb) arranged in the form of a cross as in mustard family.
· E.g mustard, radish, cauliflower etc.
(ii) Papilionaceous (Butterfly like)
· General appearance is like that of a butterfly.
· Consists of five petals
· The largest outermost one is standard or vexillum, the two lateral ones are the wings and the keel is the innermost one.
· E.g. Common in the Papilionaceae or pea family (pea, gram, bean etc)
(iii) Ligulate or strap-shaped
· Tongue like
· Corolla forms a short narrow tube below but flattened above like a strap.
· E.g Ray floret of sunflower.
(iv) Tubular
· Corolla is cylindrical or tubular more or less equally expanded from base to apex.
· E.g. disc floret of compositae.
(v) Companulate/ Funnel-shaped
· Fused petals form a funnel-shaped structure i.e, gradually spreading outward from a narrow base.
· E.g Datura, Ipomoeba
(vi) Bell-shaped or Campanulate
· Shape of corolla resembles a bell
· E.g . Gooseberry, bellflower.

· It's the mode of arrangement of the sepals or petals (more particularly) in a floral bud with respect to the members of the same whorl (calyx or corolla)
(a) Valvate aestivation
· Members of the whorl are in contact with each other but do not overlap, they are just in contact with each other by their margin
· E.g. Custard-apple
(b) Twisted or controlled
· Margins of sepals/petals overlap regularly i.e., one margin of a sepal overlaps then next and the other margin is overlapped by preceding sepal. e.g. China rose (Hibiscus)
(c) Imbricate
· Margins overlap irregularly
· One petal/sepal is completely external. One is internal and remains in a twisted manner. e.g. Cassia, Aelonix (Gulmohar) etc.
(d) Vexillary
· Five petals of which the posterior one is largest and it almost covers the two lateral petals, and the latter in their turn nearly overlap the two anterior or smallest petals.
· Universally found in papilionaceous corollas.
· e.g. Pea, bean etc.

Fig: Different Types of Corolla

· Calyx and corolla are more or less similar in shape and colour i.e, not clearly distinguishable.
· Common in monocots and the units are called tepal.
· Polytepalous – free tepal
· Gamotepalous – fused tepals
· Epiepalous – the fusion of tepals and stamen
· Epipetalous – the fusion of petals and stamen
· In Gramineae, the perianth is present as lodicules.

c. Androecium
· Male reproductive organ of a flower
· Individual unit – stamen.
· Each stamen consists of filament, anther and connective.
· Anther is usually bilobed (dithecous) and tetrasporangiate. (anther having 4 chambers)
· Two lobes of the anther are connected to the stamen by connective.
· The staminode is a sterile stamen i.e. the one not bearing pollen grains common in Caesalpinioideae
· Stamens producing pollen grains are fertile stamen.
· In Madar (Calotropis, family Asclepiadaceae) and orchids (family: Orchidaceae) pollen grains are found inside a sac-like structure known as pollinia or pollinium.
· Inserted – Stamens remaining inside the corolla or petals
· Exserted – Stamens longer than the petals and comes out of the flower.
· Epipetalous – Stamen fused with petals. e.g Malvaceae, Solanaceae, Compositeac (MSC)
· Epiphyllous – stamen fused with tepals. e.g Liliaceae
· Gynandrous – Stamen fuse with the pistil. e.g. Calotropis
· Adelphous –stamens are united by their filament only, the anthers remaining free.

Fig: Showing Androecium

Various Types
a. Monadelphous (Monos – single) – All the filaments are united into a single bundle but the anthers are free. E.g. Members of the family Malvaceae (china rose, cotton, lady's fingers) etc.
b. Diadelphous stamens (di=two)
· Filaments are united into two bundles anther remaining free.
· Common in pea family e.g pea, bean, gram, butterfly.
· In the members of the pea family, ten stamens are present of which nine are united into one bundle and the tenth one is free.
c. Polyadelphous stamens (poly=many)
· Filaments are united into several bundles generally more than two but the anthers are free. e.g. Ricinus, Bombax, Citrus
· Syngenesious stamens (syn, together or united, genes, producing)
· When the anthers are united together into a bundle or tube, but the filaments are free, the stamens are said to be syngenesis. e.g. members of family Compositae (sunflower)
d. Synandrous

· Anthers and filaments (whole stamens) are both fused. e.g. members of the Cucurbitaceae family (Cucurbita)
e. Polyadelphous stamen:
When filaments are united into the number of bundles more than two, but anthers are free, the stamens are said to be polyadelphous. eg. castor, lemon.

Fig: Different Types of Androecium

Length of stamen
i. Didynamous (di - two, dynamos- strength)
· Four stamens of which two are long and two are short.
· Two outer stamens are longer and the two inner are short.
E.g. Member of family Labiatae, Ocimum (Tulsi)
ii. Tetradynamous
· In the mustard family e.g. mustard, radish, turnip etc. there are six stamens of which the outer four are long and the inner two are short, such stamens are said to be tetradynamous.
iii. Heterostemony
· Condition in which stamens are of unequal length. e.g Cassia

Based on fixation:
a. Basifixed – Filament fused with anther from the base. e.g. Cruciferae
b. Dorsifixed – The filament is attached to the back of the anther firmly at a point but the anther is not free to swing. e.g Passiflora.
c. Adnate – The filament attached along the entire length of the anther from base to the apex. e.g Ranunculus, Michelia, members of family mango Liliaceae.
d. Versatile – The filament is attached to the back of the anther at a point in the middle and the anther can freely swing on the filament. E.g. grass (wheat, maize)

Fig: Types of fixation of anthers

d. Gynoecium or Pistil (gyne - female)
· Gynoecium or pistil is the fourth or the female reproductive whorl of flower which is composed of carpels.
· Individual unit – carpel
· Carpels are modified leaves meant to bear ovules and an embryo sac within each ovule.
· Carpel consists of stigma, style, and ovary.
· Ovary consists of one or more locules (chambers) in which ovules are located.
· Each ovule encloses an embryo sac.
· Ovary changes into fruit and ovule changes into a seed after fertilization.
· Functionless or sterile pistils are called pistillode. E.g. ray floret of sunflower.
· Apocarpous - Carpels are free from each other.
E.g. members of Magnoliaceae (Michelia)
· Syncarpous – Carpels are fused to each other.

Fig: Showing Gynoecium

1. Simple (one carpel) – eg. pea bean
2. Compound (more than one)
(i) Apocarpous
(ii) Syncarpous
· Style originate from the top of the ovary e.g. Cruciferae.
· Style originates at the lateral side e.g. Gramineae
· Gynobasic – style originates from the base of the ovary. E.g. Labiatae, osimum sanctum, calotropis
· Unilocular ovary – ovary with a single locular or single chamber. E.g Graminea, Compositae, Leguminosae

· Based on chambers or locules, the ovary is divided into.
· Bilocular – 2 locules, e.g. Cruciferae, Solanaceae
· Trilocular – 3 locules e.g Liliaceae
· Tetralocular – 4 chambered e.g Labiatae (Ocimum santum)
· Multilocular – More than five chambers. E.g lady's finger (Abelmoschus esculentis)


· Placenta: ridge of tissue in the inner wall of the ovary having one or more ovules.
· Placentation – Mode of arrangement of the placenta in the ovary.
1. Basal:
· Placenta develops directly on the thalamus bearing a single ovule from the base of the ovary.
· Commonly seen in the sunflower family (Compositae) and Gramineae.
2. Marginal:
· Ovary is one chambered and the placenta develops along the junction of two margins of the carpel. e.g. Legumes
3. Axile (lying on the axis):
· Ovary is two or many chambered and placenta bearing ovules that develop from the central axis to the confluent margins of carpels. e.g. Solanaceae, Malvaceae and Liliaceae (SML)
4. Parietal (Perietis, wall)
· Ovary is one chambered and the placenta bearing the ovules develops on the inner wall of the ovary. 
· E.g. Cruciferae, Cucurbitaceae.
· Ovary of crucifers sometimes becomes two-chambered due to the development of a false partition wall across the ovary, which is called replum.
5. Superficial
· The ovary is multilocular,
· Carpels – numerous
· Placenta develop all around the inner surfaces of the partition walls. 
· E.g. Myphaea, primitive monocot waterlily.
6. Free central
· One chambered ovary and placenta bearing ovules develop all around the central axis.
· E.g. Dianthus.
· Free central is the axile placentation without any septa.

· The most suitable flower for the study of floral parts is mustard.
· Vexillum, alae and keel of pea flower are constituents of the corolla.
· Petals possess claws in Cruciferae.
· Aestivation of the corolla in pea is vexillary (or descending imbricate).
· In the unilocular ovary, ovules develop on the inner wall of the ovary, this type of placentation is called parietal.
· In a multilocular ovary, ovules are borne on the entire inner surface. Such placentation is superficial.
· Arrangement of floral members which are partly spiral and partly whorl is hemicycle.
· Flower of Hibiscus is actinomorphic and hypogynous
· Stamens of Jowar or grass are versatile.
· Flowers are intersexual in Hibiscus.
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