BOTANY OF THE LIVING PLANT 



illustrate their very simple floral structure. In the large shrubby Goat- Willow 

 (Salix caprea, L.) the flowers appear grouped to form the well-known Catkins, 

 or " Palms." These are of two sorts, distributed on different plants (dioecious) 



FIG. 408. 

 Catkins of the Willow, a, male ; b, female. (After Figuier.) 



(Fig. 408). The male catkins appear bright yellow when in bloom, from 

 their projecting stamens ; the female catkins are more slender, and of olive- 

 green colour. In each case the catkin is a spike. Its main axis bears 



darkly-coloured bracts, and in the axil of 

 each of these is a single very simply- 

 constructed flower. 



The male flower (Fig. 409, a) consists of 

 two stamens, each with a long filament, 

 which bears the anther, with sticky, not 

 dusty pollen. There is no perianth, nor 

 gynoecium ; but on the side next the 

 stem is a nectary, which secretes honey 

 freely at flowering (Fig. 410, A, d). Other 

 species may have three, four, or more 

 stamens, but no other floral parts (Fig. 

 410, ,C). The female flower (Fig. 409, b) 



Flowers of Willow (Salix alba), a, male ; is also axillary. It consists only of a 

 i 6 s a^l e oJn.^^rVSi S 5 tending *"*' gynoecium of two carpels joined by their 



margins to form a unilocular, superior 



ovary with two-lobed stigma. The ovules are numerous, and the placenta- 

 tion parietal. A honey-gland is present here also between the flower and 

 the main axis (Fig. 411, A). 



Pollination. The flowers of both catkins are visited freely by insects, both 

 bees and moths, for honey or for pollen. Self-pollination is obviously im- 

 possible, for the plants are dioecious ; but crossing follows as a natural 



FIG. 409. 



