Specialized shoot in which leaves are modified into specialized whorls.
It is borne at the tip of a stalk @ pedicle / peduncle.
● with pedicle @ pedicellate flowers
● without pedicle @ sessile flowers
● green whorl @ sepels or calyx
● brightly colored @ petals or corolla
● male whorl @ stamens or androecium
● female whorl @ carpel or gynoecium
Complete : has all the four whorls
Incomplete : has one or more who8rl missing
Essential : whorls of a flower which are directly involved in reproduction [androecium & gynoecium]
Non essential : whorls of a flower which are not directly involved in reproduction [calyx = protects the flower in yhe bud stage & corolla = makes the flower attractive for pollination]
Bracts : leaf - like structure in the axil of which a flower grows; usually small and green in ordinary leaves & large and brightly coloured in Bougainvillea
Nectaries : special glands at the base of petals or pistil; secrete sweet and fragrant nectar to attract insects for pollination; present in Nasturtium
I. Actinomorphic flower : flower can be cut into equal halves by any vertical plane passing through the centre. Eg: Rose 🥀
also called Regular or Radially Symmetrical Flower
II. Zygomorphic flower : flower can be divided into two equal halves by only one particular plane. Eg: Basil 🌱
III. Asymmetrical flower : flower can not be divided into equal halves by any plane. Eg: Canna 🏵
Bisexual flower: both male and female reproductive parts are present. Eg: Mustard
also known as HERMAPHRODITE FLOWERS
Unisexual flower: has only one reproductive whorl. Eg: Papaya
also known as IMPERFECT FLOWER
● Staminate flower: Unisexual flower having only androecium. Eg: maple 🍁
Nonfunctional stamens @ Staminodes
● Pistillate flower: Unisexual flower having only gynoecium. Eg: cucumber 🥒
Nonfunctional gynoecium @ pistillode
● Neuter flower: both androecium and gynoecium are absent. Eg: ray florets of sunflower 🌻
I. Calyx:
outermost whorl consisting of sepals; usually green in colour
● petaloid sepals = coloured sepels [gulmohar]
● polysepalous calyx = free sepals [mustard]
● gamosepalous calyx = united sepals [china rose]
● epicalyx = an additional whorl if some leaf like structure [ hibiscus 🌺]
● deciduous flower = sepals fall off after formation of fruit [brassica]
● persistent flower = sepals persist till suit is formed [guava]
Functions:-
protects flower in bud stage
manufacture food for plant
petaloid sepals attract insects for pollination
II. Corolla:
second whorl of a flower consisting of petals; white or brightly coloured
● sepaloid = petals are green 💚
● polypetalous corolla = petals are free [mustard]
● gamopetalous corolla = petals are united [petunia]
Functions:-
protects the reproductive whorls in bud stage
provide bright colour and fragrancd to attract insects for pollination
III. Androecium:
Third whorl consisting of male reproductive whorls; has 3 parts-
1.Filament: long slender stalk which supports anther at its tip
2.Connective: joins two anther lobes
3.Anther: two-lobed and each lobe has two chambers@ pollen-sacs; 1 anther has 4 pollen sacs.
Pollen grains or Pollen are formed inside the pollen sacs. When fully mature, the pollen sacs rupture to liberate pollen grains.
Functions:-
Produce pollen grains containing male reproductive cells @ male gametes
Filament bears and supports anther in a suitable position for transfer off Pollen.
COHESION OF STAMENS
● monodelphous stamens= stamens are united to form an single staminate tube [China rose]
● diadelphous stamens= stamens are united into two bundles and anthers remain free [pea]
● polydelphous stamens= filaments are united to form many bundles and anthers are free [silk cotton]
● syngenesious stamens= filaments are free and anthers are united tu form a bundle [sunflower]
● synandrous stamens= both anthers and filaments are fused along their length [guord]
IV. Gynoecium
Innermost whorl of a flower consisting of female reproductive parts; located at the centre of thalamus; consists of one or more carpels; caperls consists of 3 parts:-
1.Stigma: terminal knob-like part of carpel; sticky or feathery; adapted to receive pollen.
2.Style: slender stalk arising from ovary and bear stigma at its apex.
3.Ovary: swollen basal part; contains ovules; a female gamete or egg cell is produced in each ovule.
Unilocular ovary- only one chamber inside it