524 ANGIOSPERMAEMONOCOTYLEDONES 



each forming a boat-shaped cavity, in which the pollen rests while the air is calm. 

 When the anthers are shaken by wind, this is removed little by little, until the loculi 

 are completely empty. 



Fig. 418. Arrhenantherum elatius, Mert. et Koch (after Kerner). (1) Undehisced anther. 2) 

 Dehisced do. (3) Spikeletwith open glumes, and anthers hanging down in still air. (4) Do., when 

 the air is in motion. The anthers of one flower are shedding their pollen, those of another have already 

 done so (and one has dropped from its filament), those of a third have not dehisced and are pushing their 

 way out from between the glumes. 



1000. Avena L. 



3023. A. Scheuchzeri All. Kirchner (' Beitrage,' p. 8) describes this speci< 

 as homogamous, but the stigmas remain receptive and hang down between th 

 glumes when the anthers have fallen. 



3024. A. pubescens L. This species, according to Kirchner (' Flora v. Stut 

 gart,' p. 134), is feebly protogynous with persistent stigmas. The anthers do m 

 dehisce until a short time after the divergence of the glumes, while the stigmas ai 



II 



