2. TOPIC TO BE DISCUSSED
• Flower
• Floral terminology
• Parts of a Typical Flower
3. INTRODUCTION FLOWER
The flower is a highly modified shoot meant essentially for sexual
reproduction in plants.
Typically, it is a collection of four different kinds of four floral members
arranged in four separate whorls or circles.
It contains two accessory whorls and two essential whorls.
Flower exhibits wide variation in shape size and arrangement of floral
parts. However, all flowers have same basic plan
4. FLORAL TERMINOLOGY
braceteate- with distinct bract
Ebraceteate- without bract
Bracteolate- with bracteole
Ebracteolate- without bracteole
Pedicellate- with pedicel
Sessile- without pedicelbisexual
Complete- with four whorls
Incomplete- lacking any of four
whorls
Achlamydeous- Without perianth.
Monochlamydeous- single whorl of
perianth
Dichlamydeous- Both the whorl of
perianth.
Bisexual- having both sex organs.
Unisexual- having any one
reproductive organ
Neuter- without samens and carpels.
5. Bimerous- with floral parts 2 or multiple of 2
Trimerous- with floral parts 3 or multiple of 3
Tetramerous- with floral parts 4 or multiple of 4
Pentamerous- with floral parts 5 or multiple of 5
Heteromerous- with different basic number in any of its floral whorls.
Cyclic- All the floral organs occurs in definte whorls.
Acyclic- All the floral organs brone in spirals and not in whorls.
Spiraocyclic- some floral parts arranged in whorls and others in spirals.
Actinomorphic- a flower that can be cut into two equal halves by any vertical
plane
Zygomorphic- a flower that can be cut into two equal halves by only one
vertical plane.
Assymetric- a flower that can not be cut into two equal halves by any plane.
7. PARTS OF A TYPICAL FLOWER
Flower develops on the mother axis in the form of floral bud. A typical flower has
following parts
8. 1. Bract :- Leaf like structure in whose axil a flower often develops.
• Foliaceous:- Green, leaf like
• Spathe:- large, boat shaped
• Petaloid bracts :- bright coloured bracts
• Involucre:-Group of bracts in a cluster
• Glumes:- small and dry scales
• Scaly bract:- present at the base of each floret
• Epicalyx:-whorls of bracteoles arise at the base of calyx
9. 2. Pedicel:- Stalk of the flower, which may be short, long or even absent
3. Bractioles :- Scally appendages present on pedicel
4. Receptacle:- swollen or expanded tip of pedicel, which bears four whorls.
5. Floral whorls:-
i. CALYX:- outer most protective whorl. Individual member called sepal.
Colour:-
• sepaloid:- sepals are green
• Petaloid –sepals are coloured
Fusion:-
• Polysepalous- sepals are free, e.g., Mustard
• Gamosepalous- sepals are united , e.g., Datura
10. Duration:-
• Caducous :- sepals falls early on prematurely
• Deciduous:-sepals fall-off along with petals just after fertilization
• Persistent:- Remain attached to the fruit, e.g., tomato.
• Marcescent:- persistent calyx , e.g., guava
• Accrescent:- persistent calyx but growing in size along with the fruit , e.g., physalis.
Modifications of calyx:-
11. ii. COROLLA :-
Colour:-
• Petaloid:- petals are coloured
• Sepaloid :–petals are green
Fusion:-
• Polysepalous- petals are free, e.g., Mustard
• Gamosepalous- petals are united , e.g.,
Datura
Shape :- Polypetalous and regular • Polypetalous and irregular:-
12. • Gamopetalous and regular:-
Aestivation of Corolla and Callyx:-
• Gamopetalous and irregular:-
13. iii. Perianth:-
• When non-essential whorls (sepals and petals) are not distinct, they are collectively
called perianth. The individual members of perianth are known as tepals,
e.g.,Asphodelus.
iv. Androecium:
• Androecium, the male reproductive whorl of flower, is composed of stamens.
• A stamen is made up of chiefly two parts: a large terminal portion called anther, and
a stalk known as the filament.
14. 1. Number:
(a) Monandrous – one stamen
(b) Diandrous – two stamens
(c) Triandrous-three stamens
(d) Polyandrous- many stamens
2.Position
(a) Inserted–stamens remain inside the corolla tube, e.g., Petunia.
(b) Exserted – stamens are longer and exposed out the corolla tube, e.g., Hibiscus, Acacia
3. Length of Stamens:
(a) Isostemonous-when all stamens of a flower are of equal lengths, e.g., solarium.
(b) Heterostemnous – when length of stamens are unequal, e.g., Cassia
(c) Didynamous – stamens four, 2 short and 2 long, e.g., Ocimum
(d) Tetradynamous – stamens six, two outer short and inner four long, e.g., Brassica.
15. 4. Arrangement of stamens:
(a) Diplostemonous – Stamens arranged in two whorls, outer whorl alternate with the
petals (alternipetalous) and the inner whorl is opposite to petals (antipetalous), e.g.,
Cassia.
(b) Obdiplostemonous – When outer whorl of stamens is antipetalous and inner whorl
is alternipetalous, e.g., Dianthus.
(c) Polystemonous – stamens arranged in more than 2 whorls.
5.According to fertility :
(a) Fertile stamens-Stamens producing pollen.
(b) Staminode- stamens do not produce pollen i.e. non-functional, e.g., Salvia, Cassia.
6. According to anther lobe:
(a) Monothecous -one-lobed anther, having 2 pollen chambers (bisporangiate), e.g.,
Malvaceae family.
(b) Dithecous-two-lobed anther, having4 pollen chambers (tetrasporangiate), e.g.,
Mustard.
16. 7. Cohesion of Stamens:
(a) Adelpnous-When filaments are united but anthers remain free.
It is of three types –
(b) Syngenesious – When anthers of stamens are fused and filaments remain free,
e.g.,Helianthus, Tridax.
(c) Synandrous – When stamens are fused throughout their length, e.g., Cucurbita.
(d) Polyandrous – When stamens are free from one another, e.g., Ranunculus, Iberis
etc.
17. 9.Fixation of anthers.
v. Gynoecium:
• Gynoecium, the female reproductive whorl of flower, consists of carpels.
• A carpel is differentiated into 3 parts-stigama, style and ovary.
18. 1. Gynoecium may be classified broadly into two types:
(a) Simple or Monocarpellary:
It is composed of only one carpel, e.g., pea, all legumes.
(b) Compound or Multi-capillary:
It comprises more than one carpel. Such a type of gynoecium occurs in majority of seed plants.
Apocarpous: Each carpel is free from the other forming a separate gynoecium, e.g., Ranunculus,
Clematis, etc.
Syncarpous: All the carpels are fused with one another forming a compound gynoecium, e.g.,
Brassica (mustard),
2. Number of Carpels:
Depending upon the number of carpels it is of following types
(i) Bicarpellary: Comprises two carpels, e.g.,Sonchus, Coriandrum, Mussaenda.
(ii) Tricarpellary: With three carpels, e.g., Allium cepa (onion), etc.
(iii) Tetracarpellary: With four carpels, e.g., Duranta, Berberis, etc.
(iv) Pentacarpellary: With five carpels, e.g.. Hibiscus (China rose), Media (Neem), etc.
(v) Multicarpellary: With more than five carpels, e.g., Papaver.
19. 3. Stigma:
It is the terminal part of pistil meant for receiving pollens at the time of pollination. On the basis
of shape, stigma may be
4. Style:
It is the tubular stalk that connect stigma with ovary.
(a) Terminal or Apical:
When style lies in the same straight line with the ovary, e.g., Hibiscus, Dianthus, etc.
(b) Lateral:
When style appears to be arising from the side of the ovary, such as in strawberry, mango.
20. (c) Gynobasic:
The ovary is lobed and the style arises from
the depression in the centre of the ovary.
Such a style is termed as gynobasic, e.g.,
Ocimum.
(d) Petaloid:
When the style becomes flattened and
coloured like petals, e.g., Canna, Iris.
5. Ovary:
It is the lowermost (basal) part of the
gynoecium, develops by the in rolling of the
carpels (megasporophylls) along the median
line.
21. Position of the ovary on thalamus:
Chambers of ovary:
(i) Unilocular:
Ovary with a single chamber, e.g., Pisum .
(ii) Bilocular:
Ovary with two chambers, e.g., Solarium,
(iii) Trilocular:
Ovary with three chambers, e.g., Asphodelus
22. Placentation:
The ovary of flower possesses one or more ovules which later on develop into seeds after fertilization. The ovule
bearing region of the carpel is called placenta.
(a) Marginal: When the gynoecium is monocarpellary apocarpous, the placentae bearing ovules are borne on
the ventral suture, where the margins of the ovary wall fuse .
(b) Axile: Ovary multilocular and ovules borne on central placenta, e.g., Hibiscus
(c) Parietal: Ovary is unilocular but pistil is syncarpous. The ovules are borne on peripheral fused margins of
carpels, e.g., Brassica, etc.
(d) Free central: Ovary is unilocular and ovules borne on a central column which is not connected to the ovary
wall by any spetum, e.g., Dianthus, Silene, Primula etc.
(e) Basal: Ovary is unilocular and a single ovule is borne at the base of the ovary.
(f) Superficial: Ovary is multilocular and the ovules are borne on septa as well as all over the inner surface,