1290 A TEXTBOOK OF THEORETICAL BOTANY 



anther lies in the base of the flower with the curved filament held in a state 

 of compression and the anther pressed against the abortive ovary, which 

 stands in the centre of the male flower. Due apparently to the motion of the 



Fig. 1 22 1. — Urtica dioica. A, Flowering shoot. B, Young male flower. C, Mature 

 male flower with stamens recurved and discharging pollen. D, Female flower 

 with pendent, bushy stigma. 



wind, the anthers are finally released and the filaments straighten out sud- 

 denly, like a spring, accompanied at the same time by the splitting of the 

 anthers. This simultaneous dehiscence and ejection scatters the powdery 

 pollen widely enough to reach adjacent plants in which the stigmas are 

 receptive. The same explosive mechanism is exhibited by the allied genera 

 Parietaria and Pilea (the Artillery Plant (Fig. 1222)), where the discharge 

 is even more vigorous. 



5. Motionless Type 



This type of wind pollination is exhibited by two contrasting groups, 

 both of which belong to the Monocotyledons. The first includes a large 



