PREFACE. xix 



Grisebach has discussed fully (' Naehrichten k. Gesell. 

 der Wissen. zu Gottiiigen/ June 1, 1878) the cleisto- 

 gaihic flowers produced by Cardamine 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 Ammannia latifolia bears cleistogamic 

 flowers. According to Mr. Bessey (the 'American 

 Natutalist,' 1878, p. G9) this is likewise the case with 

 Lithospermum longiflorum. Three genera of Orchideas 

 have been added to the list, from information given me 

 by Mr. Spencer Moore and from some remarks in 

 * Journal of Botany,' 1877, p. 377. Lastly, Mr. Bennett 

 has published ('Journ. 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. 338) on the author- 

 ity of Mr. Wallis, that Drosera rotundifolia opens its 

 flowers only early in the morning, Mr. Conybeare in- 

 forms me that he once saw in Cornwall, at 2 v. 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. 337) 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 

 ('Nature,' April 4, 1878, p. 446) has called attention 

 to some observations made long ago by Mr. Bentham 

 (' Catalogues des Plantes indig. des Pyr^ndes,' 1826, p. 

 85) on the fruiting of Helianthemum prostratum. He 

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

 Helianthemum and some other plants (for instance, of 



