xviii 



PREFACE. 



advanced by me; see, for instance, 'Journal of Botany,' 

 Dec. 1877, p. 376. 



I have stated (p. 13) that after inquiring from sev- 

 eral botanists I could hear of no instance, except a doubt- 

 ful one, of plants in an andro-dioecious condition, or ex- 

 isting as hermaphrodite and male individuals. But II. 

 Miiller ('Nature,' Sept. 12, 1878, p. 159) has found on 

 the Alps Veratrum album, Dryas octopetala, and Geum 

 reptans in this condition. It is an interesting fact that 

 the corollas of the male flowers are not diminished in 

 size like those of the females of gyno-dioecious plants. 

 Asa Gray has also reason to suspect that Diospyros vir- 

 giniana may be andro-dioecious. 



The eighth chapter is devoted to cleistogamic flowers, 

 and I have struck out of the list there inserted four 

 genera, owing to information given me by Mr. Bentham 

 and Asa Gray. On the other hand, fifteen genera have 

 been added. Mr. Bentham informs me that the S. 

 American Trifolium polymorphism produces true cleis- 

 togamic flowers. Dalibarda, Milium, and Yilfa have 

 been added to the list on the authority of A. Gray in a 

 review of this book in the ' American Journal of Sci- 

 ence.' The cleistogamic flowers of Danthonia are de- 

 scribed by Pringle, in the ' American Naturalist,' 1878, 

 p. 248, and those of another Gramineous genus, Di- 

 plachne, by Ascherson, in ' Sitzungsb. der Gesell. Natur. 

 Freunde, Berlin,' Dec. 21, 1869. Krascheninikovia has 

 been added from some remarks made in ' Journal of 

 Botany,' 1877, p. 377. Batalin has published an essay 

 ('Act. Hort. Petropol/ torn. v. fasc. 2, 1878), 'Kleisto- 

 gamische Bliithen der Caryophylleen,' namely, on Ceras- 

 tium and Polycarpon. F. Ludwig has described the cleis- 

 togamic flowers of Collomia grandiflora in ' Sitzb. Bot. 

 Vereins. Brandenburg.' Aug. 25, 1876 : see also on same 

 subject Scharlok, in 'Bot. Zeitung,' 1878, p. 641. A. 



