Page 16 - Lesson Notes-Morphologyof flowering plant

polypetalous (petals free). The shape and colour of corolla may vary greatly in
shape. Corolla may be tubular, bell-shaped, funnel-shaped.
Aestivation
The mode of arrangement of sepals or petals in floral bud with respect to the other
members of the same whorl is known as aestivation. The aestivation pattern is
important in classification of – plants.
It is of following types
(a) Valvate Petals come to each other but do not overlap, e.g., mustard (Brassica).
(b) Twisted Regular overlapping of petals occurs in which margin of one petal
overlap with the next one petal, e.g., China rose (Hibiscus rosa sinensis).
(c) Imbricate There are five petals, arranged in such a way that one petal is
completely external and another petal is completely internal, while three petals are
partially external and partially internal, e.g., Cassia, Cullistemon,Caesalpinia.
(d) Vexillary When the largest petal overlaps the two lateral petals which in turn
overlap the two smallest anterior petals (keel), the aestivation is called as vexillary or
papilionaceous.

iii.Androecium
It is the third whorl of flower composed of stamens or microsporangium. Each
stamen, which represents the male reprodutive organ consists of a stalk or a
filament and an anther. Each anther is usually bilobed which are attached at the back
by a sterile band called connective and each lobe has two chambers, the pollen sacs.
The pollen grains are produced in pollen sacs. A sterile stamen is called staminode.
Stamens can be of different types depending on their union with other members
such as petals or among themselves.
(a) When stamens are attached to the petals, they are epipetalous, e.g., Brinjal.
(b) When stamens are attached to the perianth, the condition is called epiphyllous,
e.g., Lily.
(c) The stamens in a flower may either remain free, i.e., polyandrous or may be
united in varying degrees.
(d) The stamens may be united into one bunch or one bundle, i.e., monoadelphous as
in China rose. It may be two bundles, i.e., diadelphous as in pea or into more than
two bundles, i.e., polyadelphous as in citrus.