GRAMINEAE 529 



IOI2. Bromus Dill. 



3052. B. secalinus L. — Hildebrand (' Bestaubungsverh. d. Gramineen ') 

 describes this species as homogamous. Self- and cross-pollination are possible to 

 about the same extent. In favourable weather the flowers remain closed, and pseudo- 

 cleistogamous fertilization takes place. Beijerinck describes the species of Bromus 

 as self-fertile, and in Holland usually cleistogamous. 



3053. B. erectus Huds. — Kirchner (' BeitrSge,' pp. 9-10) says that this species 

 is homogamous. The orange-yellow anthers bend downwards, however, directly 

 after the divergence of the glumes, and also dehisce in that direction, so that as 

 a rule self-pollination is not effected. 



3054. B. mollis L. — The flowers of this species are usually only cleistogamous; 

 chasmogamous ones have only twice been met with, between 7 and 8 a.m., and 10 

 and II a.m., closing again after a few hours (Warnstorf, Verh. bot. Ver., Berlin, 

 xxxviii, 1896). 



Visitors. — Herm. Muller observed a beetle. 



3055. B. sterilis L. — This species has only been observed bearing cleistogamous 

 flowers (Warnstorf, Verh. bot. Ver., Berlin, xxxviii, 1896). 



3056. B. tectorum L. — This species usually bears cleistogamous flowers, and 

 has only once been observed (at 6 p.m.) with open flowers and projecting stigmas 

 and stamens (Warnstorf, op. cit.). 



1013. Triticum L. 



3057. T. vulgare Vill. — Delpino states that in this species the glumes diverge 

 rapidly and suddenly. The anthers project laterally at the same time, dehisce, and 

 empty about one-third of their pollen on the stigma of the same flower, while the 

 rest is scattered into the air. This happens in about one minute, and after a quarter 

 of an hour the glumes again close. 



Delpino's experiments show that automatic self-pollination results to the setting 

 of good fruits. He and Kornicke state that each flower remains open only about 

 a quarter of an hour, but anthesis lasts four days, so that only a small number of 

 flowers are found open at any one time (Herm. Muller, ' Fertlsn.,' p. 568). 



Kirchner (• Flora v. Stuttgart,' p. 155) says that the homogamous flowers gradually 

 open so widely that the tips of the glumes are about 4 mm. apart. The anthers 

 dehisce apically at the same time, and about one-third of their pollen falls into the 

 flower. They project after this and scatter the rest into the air. Self-pollination 

 therefore takes place regularly, but cross-pollination by means of the wind is not 

 excluded. The anthesis of a spike lasts four days. 



Hildebrand states that self-pollination is rendered difficult by the tipping over of 

 the anthers after the divergence of the glumes. 



The flowers of the wheat resemble those of the rye as regards anthesis. 



Godron says that the flowers open at 4.30 p.m. at 16° C, closing again at 

 6.30-7 p.m. If the anthers tip over quickly when the flower opens, the stigmas of 

 the blossom are not as a rule dusted with their pollen. Under less favourable 

 circumstances anthesis takes place more slowly, and the stigmas do not project until 



