PLANT DESCRIPTION ‘ 227 
Pollination.—Self-pollination often occurs, since, in’ 
most cases, stamens and carpels ripen at the same time. 
Small flowers with spreading petals are visited by 
short- tongued insects (flies, ete.), and some of them 
(e.g., Shepherd’s purse, whose flowers often have only 
CRUCIFERAE 
ECTION: OF- WALLFLOWER 
SILIQUA- -OF 
WALLFLOWER 
FIG.196 
ii ogre, ia 
€ (9: 
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STAMENS-AND-PISTIL 
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F°SILIQU 
OF -SILIQUA 
SILICULA* OF- SHEPHERDS - 
two to four stamens) are regularly self-pollinated. 
The larger flowers, in which the sepals are erect and 
hold the clawed petals together so as to form a sort 
of flower tube, are visited by bees and butterflies, 
the nectar being partly concealed and _ protected 
from the rain. The large light-coloured evening- 
