GRAMINEAE 533 



or else the anthers remain enclosed between the glumes during anthesis. But even 

 in the first case automatic self-pollination is almost inevitable on account of the slight 

 opening of the flowers and the early dehiscence of the anthers ; it seems to be much 

 more general than in wheat. 



Kirchner ('Flora v. Stuttgart/ p. 159) says that the flowers of the two middle 

 rows never open, but fertilize themselves pseudo-cleistogamously. Those of the 

 lateral spikelets, on the contrary, open regularly ; they are homogamous, and possess 

 the same mechanism as those of wheat, so that automatic self-pollination usually 

 takes place. 



3070. H. hexastichon L. Rimpau states that the flowers of this species open 

 at a temperature of 1 2^ C. The middle spikelet seems to fade almost with closed 

 glumes, but it sometimes opens ; the lateral spikelets always open. Godron states 

 that the flowers of all six rows of spikelets are hermaphrodite and fertile. 



3071. H. Zeocriton L. Rimpau says that the anthers of this species always 

 dehisce while the glumes are completely closed. Godron also observed only 

 cleistogamous flowers. Hansgirg describes them as pseudo-cleistogamous. 



3072. H. murinum L. Hildebrand says that in this species the flowers of the 

 two middle rows of spikelets remain closed, and fertilize themselves. Those of the 

 lateral ones are male. Their anthers project widely, so that their pollen can 

 fertilize any hermaphrodite flowers which are opening. The lateral male flowers 

 scatter their pollen between 6 and 7 a.m. ; the blossoms of the middle spikelets are 

 hermaphrodite and cleistogamous. (Warnstorf, Verh. bot. Ver., Berlin, xxxviii, 1896.) 



3073. H. bulbosum L. Hildebrand says that in this species two lateral male 

 flowers are situated near each hermaphrodite one, and their anthers dehisce later. 

 When the hermaphrodite flowers open, the anthers first force their way through the 

 glumes. The stigmas then project downwardly to right and left through a slit in 

 the latter on the side facing the axis of the spike. After the anthers have turned 

 over, their dehiscent tips are situated below the stigmas, which remain receptive for 

 some time after the pollen has been scattered. Cross-pollination may therefore easily 

 take place, and can be effected by the pollen scattered from the lateral male flowers, 

 the anthers of which dehisce subsequently. Wittmack considers the latter impossible ; 

 in specimens which he cultivated he found the pollen of the middle flowers completely 

 ineffective. Sexual reproduction has undoubtedly been rendered superfluous by 

 vegetative propagation, effected by means of the bulbous base of the stem. (According 

 to Loew, ' Blutenbiol. Floristik,' pp. 370-1.) 



1018. Sorghum L. 



3074. S. vulgare Pers. (= Andropogon Sorghum Brot.). (Kornicke, op. cit. ; 

 Kirchner, 'Neue Beob.,' p. 11.) Kornicke says that the flowers of this species open 

 in the morning, when the glumes separate a little and stamens and stigmas protrude 

 simultaneously. The filaments then bend over, but the anthers do not dehisce for 

 some time, and the stigmas are usually pollinated before this takes place. Autogamy 

 by retention of the reproductive organs between the glumes is not excluded. 

 Kirchner describes this species as protogynous. He says that as soon as the glumes 

 begin to diverge, the brush-like stigmas project laterally from between them. When 



