206 A TEXTBOOK OF GENERAL BOTANY 

Fia. 203. Flower of grape- 
fruit (Citrus) with a portion 
of calyx and some of petals 
and stamens removed 
pd, pedicel ; t, torus; n, nec- 
tary “ec, calyx: p, petal; J, 
filament of stamen; a, an- 
ther; o, ovary; sy, style; 
8, stigma. (x 1) 

Fig. 204. Irregular flower 
of a legume, E’rythrina fusca. 
(x 3) 
called the funiculus. Each ovule con- 
tains an egg which is the female repro- 
ductive cell. 
Stamens. A stamen consists of two 
parts (Fig. 206) : a large terminal por- 
tion, which is the anther, and a stalk 
known as the filament. The anther con- 
tains cavities called pollen sacs, in which 
pollen grains are produced (Figs. 206, 
207). Pollen grains from the anthers 
are carried by the wind, by insects, or 
by other agencies and deposited on the 
stigma of the pistil. This transfer is 
known as pollination, and when it has 
taken place the flower is said to be 
pollinated. 
Fertilization. A pollen grain, after 
being deposited on the stigma, pro- 
duces a long tube which grows down 
through the stigma and style and 
enters one of the ovules in the ovary 
(Fig. 4). Two male nuclei are found 
at the end of this tube. One of these 
enters the egg of an ovule and fuses 
with the nucleus of the egg. This 
fusion of male and female nuclei is 
called fertilization, and the flower is 
said to be fertelzzed when this has taken 
place. After fertilization the ovule 
develops into a seed, while the whole 
ovary becomes a fruit. 
Sexuality of flowers. Usually sta- 
mens and pistils are found in the same 
flower (bisexual flowers) (Figs. 202, 203), 
but frequently they occur in different 
ones (unisexual flowers). When they 
