522 ANGIOSPERMAEMONOCOTYLEDONES 



989. Apera Adans. 



3008. A. Spica-venti Beauv, (= Agrostis Spica-venti L.). (Godron, 'Flor. d. 

 Gramindes/ 1873.) This species is dependent upon self-pollination, the glumes 

 diverging widely, but the anthers being closely apposed to the feather}' stigmas during 

 anthesis. Warnstorf describes the flowers as homogamous, and says that those in 

 the upper branches of the panicles mature first, their glumes diverging before 6 a.m-., 

 and the greenish anthers dehiscing; the stigmatic branches are vertical, and the 

 anthers at first situated on stiff filaments, so that autogamy can easily take place. 



990. Calamagrostis Adans. 

 In flowers of species belonging to this genus Kemer states that the pollen is 

 scattered about 12-1 o'clock. 



3009. C. neglecta Gaertn. Mey. et Schreb. The flowers of this species are 

 homogamous; they dehisce between 6-7 a.m. The pollen-grains are yellowish in 

 colour, irregularly tetrahedral, almost glabrous, on an average 37 /* in diameter 

 (Warnstorf). 



991. Ammophila Host. 



3010. A. arundinacea Host (= Calamagrostis arenaria Roth). This species 

 is feebly protogynous ; the stigmatic branches do not protrude, and are receptive 

 within the still closed glumes, while the undehisced anthers already project slightly 

 from their tips. The filaments do not usually elongate until after the pollen has been 

 shed, when they tip over, so that autogamy generally takes place. The pollen-grains 

 are pyramidal, up to 50 /u, long and 37 /u, broad (Warnstorf). 



3011. A. arenaria Link (= Psamma arenaria Roem. et Schult.; and A. 

 arundinacea, according to the Index Kewensis). 



Visitors. Knuth (Helgoland dunes) observed many flies. 



992. Milium L. 



3012. M. efTusum L. This species is feebly protogynous, according to 

 Kirchner (' Neue Beob.'). 



993. Stipa L. 

 Kerner states that the species of this genus (not including Aristella) are some- 

 times cleistogamous. Hansgirg describes them as pseudo-cleistogamous. 



3013. S. pennata L. Hildebrand describes this species as homogamous, and 

 about equally dependent upon cross- and self-pollination. 



994. Phragmites Trin. 



3014. P. communis Trin. (= Arundo Phragmites L). Deichmann says that 

 this species is subject to cross-pollination. 



995. Sesleria Scop. 



3015. S. coerulea Arduin. Kirchner (' Beitrage,' p. 8) describes this species 

 as markedly protogynous. 



3016. S. argentea Savi (= S. elongata Host). Hildebrand states that this and 

 other species are protogynous, so that self-pollination is excluded. 



