GRAMINEAE 523 



996. Koeleria Peis. 



3017. K. cristata Pers. — Hildebrand and Kirchner describe this species as 

 homogamous. Kirchner (' Beitrage,' p. 8) states that the stigmas protrude laterally 

 between the divergent glumes, and the blue-black anthers are situated on stiffly- 

 vertical filaments 6 mm. long, so that automatic self-pollination can easily take place. 

 Hildebrand says that crossing is possible later on, for the receptive stigmas still 

 project for some time from the already closed glumes. 



997. Deschampsia Beauv. 



3018. D. caespitosa (=Aira caespitosa Z.). — Kerner states that this species 

 sheds its pollen between 5 and 6 a.m. 



3019. D. flexuosa Trin. (=Aira flexuosa Z.). — Kirchner ('Beitrage,' p. 8) 

 describes this species as homogamous, but the flowers are still open and the stigmas 

 receptive after the blue-black anthers have fallen. Only cross-pollination, therefore, 

 can then take place. Kerner says that the anthers dehisce between 5 and 6 p.m. 



998. Holcus L. 



3020. H. lanatus L. — Hildebrand (' Bestaubungsverh. d. Gramineen ') describes 

 this species as andromonoecious. Each spikelet contains two flowers, one herma- 

 phrodite homogamous and one male. Cross- and self-pollination are about equally 

 favoured. Hildebrand states that the flowers open at midday ; Kerner says that the 

 flowers of this and other species of the genus may open twice on the day of flowering 

 if the weather is favourable and the temperature 14° C, i.e. at 6 a.m. and 7 p.m., but 

 this anthesis lasts only 15-20 minutes. 



Kornicke says that in this species the chief flowering time is in the evening, 

 while that of the morning is of a secondary nature ; this order is exactly reversed in 

 H. mollis L. Kornicke, however, thinks it not improbable that the secondary 

 flowering may be suppressed. 



Warnstorf describes the pollen-grains as white in colour when examined in 

 water, globular, smooth, about 31 /x in diameter. 



3021. H. mollis L. — MacLeod (Bot. Jaarb. Dodonaea, Ghent, v, 1893, p. 301) 

 says that in this species the arrangement of flowers in the spikelet is the same as in 

 the preceding one. 



999. Arrhenantherum Beauv. 



3022. A. elatius Mert. et Koch. (Godron, 'Floraison d. Gramin^es,' 1873; 

 Kirchner, 'Beitrage,' p. 89; MacLeod, Bot. Jaarb. Dodonaea, Ghent, v, 1893, 

 pp. 299-301 J Kerner, 'Nat. Hist. PI.,' Eng. Ed. i, II, p. 297.) — This species is 

 andromonoecious. Each spikelet contains two flowers, one hermaphrodite homo- 

 gamous and one male ; the two open simultaneously. The filaments then fall over 

 immediately, so that the anthers hang downwards. The latter dehisce at their tips, 

 so that automatic self-pollination is usually excluded (Kirchner). When they dehisce 

 the anthers project widely, according to Kerner, owing to the great elongation of the 

 filaments, which increase their original length three to four times in ten minutes. 

 The filaments, at first stiff", now become limp, the anthers tip over and dehisce at 

 their downwardly directed apices. The anther-lobes diverge in opposite directions. 



