Page 48 - Pharmacognosy-I (02-06-06-102)

Number of Stamens:
When stamens are small in number they are said to be

definite, but when very numerous and not easily counted, they are
said to be indefinite.
Insertion of the stamens:

As corolla, the stamens may be hypogynous, perigynous or
epigynous, in addition adhesion may occurs between stamens and
petals, thus the stamens appear inserted upon or fused with the
corolla e.g. Asteraceae, where they are described as epipetalous.
Structure of the stamen:

1- The filament: It consists of a protective epidermis enclosing
a soft loose parenchymatous tissue, longitudinally traversed
by a small central vascular strand.

2- The connective: It consists of parenchymatous cells with a
small vascular strand continuous with that of the filament.

3- The anther-lobes: It encloses two pollen-sacs, containing
pollen grains. The wall of the anther-lobe-consists of :

a- An outer epidermis called exothecium with occasional
stomata.

b- Nutritive layer tapetum to inner side.
c- Between the exothecium and tapetum are two or three layers

of large parencymatous cells forming the endothecium. The
outer-most layer of the endothecium becomes thickened with
spiral bands appearing in side view as lignified bars parallel
and perpendicular to the anther wall. This is known as

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