XVIL] BOTANY. 69 



104. Stamens are variously inserted, but always 

 within the calyx and corolla and outside the pistil, if 

 these be present. They vary in number, and may be 

 in one or more series ; when equal in number to the 

 petals or divisions of the perianth, they usually alter- 

 nate with these in Dicotyledons, but are opposite to 

 them in Monocotyledons ; when twice as many they 

 are alternate and opposite. They are inserted on the 

 receptacle in the buttercup (Fig. 22), on the calyx in 

 the bramble (Fig. 23), on the disk in the lime, on the 

 corolla in the primrose (Fig. 29), and are combined 

 with the pistil in the orchis (Fig. 43). The filaments 

 are free in most plants; more or less combined in 

 the mallow (Fig. 26) ; combined by bundles in St. 

 John's wort ; nine are united together and one is free 



FIG. 47. Stamens of pea, nine combined and one free ; enlarged. 



in the pea (Fig. 47). The anthers are usually free, 

 but combined in the thistle and daisy, the filaments 

 being free. 



105. The anther in its early state is a cellular 

 2-lobed body, with longitudinal rows of special cells 

 in the centre of each lobe. The contents of each of 

 these special cells (called mother-cells) divide into four, 

 which form as many pollen grains. These pollen grains 

 acquire first one and then a second cellulose- (Par. n) 

 coat, and finally escape from the mother-cell and lie 

 loose in the cavity of the anther. 



