PREFACE. XIX 



has discussed fully (Nachrichten k. Gesell. der Wissen. 

 zu Gottingen, June 1, 1878) the cleistogamic flowers 

 produced by Oardamine chenopodifolia, which bury 

 themselves in the ground. See also on same subject 

 Drude in Sitzb. der Versamml. d. Naturf. in Cassel, 

 1878. From a note received from Dr. Koehne it is 

 clear that Ammafmia latifolia bears cleistogamic flowers, 

 According to Mr. Bessey (The American Naturalist, 

 1878, p. 69) this is likewise the case with Lithosper- 

 m/wm longiflorum. Three genera of Orchideae have 

 been added to the list, from information given me 

 by Mr. Spencer Moore and from some remarks in 

 Jomnal of Botany, 1877, p. 377. Lastly, Mr. Bennett 

 has published (Journal Linn. Soc. Bot., No. 101, 1879) 

 some additional " notes on cleistogamic flowers," chiefly 

 on those of Viola and Impatiens. 



With respect to the statement (p. 329) on the 

 authority of Mr. Wallis, that Drosera rotumdifolia 

 opens its flowers only early in the morning, Mr. 

 Conybeare informs me that he once saw in Cornwall, 

 at 2 P.M., the ground " starred over with the fully- 

 expanded flowers of this plant." He had previously 

 long endeavoured to find a plant with open flowers. 



The number of species in which pods produced by 

 cleistogamic flowers bury themselves in the ground is 

 remarkable. I have attributed (p. 338) this action to 

 the advantage gained by their protection from various 

 enemies, and much may be said in favour of this view ; 

 but Mr. "W. Thiselton Dyer in an interesting article 

 {Natwre, April 4, 1878, p. 446) has called attention 

 to some observations, made long ago by Mr. Bentham 

 (Catalogue des Plantes indig. des Pyrenees, 1826, p. 85) 

 on the fruiting of Eeliamthemmn prostraimn. He 

 believes, as does Mr. Dyer, that the capsules of this 

 Helianthemum and some other plants (for instance, of 



