INTEODUOTION. 13 



as andro-dioecious. But, after making inquiries from 

 several botanists, I can hear of no such cases. Lecoq, 

 however, states,* but without entering into full details, 

 that some plants of Caltha palustris produce only male 

 ilowers, and that these live mingled with the her- 

 maphrodites. The rarity of such cases as this last one 

 is remarkable, as the presence of hermaphrodite and 

 male flowers on the same individual is not an un- 

 usual occurrence ; it would appear as if nature did 

 not think it worth while to devote a distinct indi- 

 vidual to the production of pollen, excepting when 

 this was indispensably necessary, as in the case of 

 dioecious species. 



I have now finished my brief sketch of the several 

 cases, as far as known to me, in which flowers differing 

 in structure or in function are produced by the same 

 species of plant. Full details will be given in the fol- 

 lowing chapters with respect to many of these plants. 

 I will begin with the heterostyled, then pass on to 

 certain dioecious, sub-dicecious, and polygamous species, 

 and end with the cleistogamic. For the convenience of 

 the reader, and to save space, the less important cases 

 and details have been printed in smaller type. 



I cannot close this Introduction without expressing 

 my warm thanks to Dr. Hooker for supplying me with 

 specimens and for other aid; and to Mr. Thiselton 

 Dyer and Professor Oliver for giving me much in- 

 formation and other assistance. Professor Asa Gray, 

 also, has uniformly aided me in many ways. To Fritz 

 Miiller of St. Oatharina, in Brazil, I am indebted for 

 many dried flowers of heterostyled plants, often accom- 

 Danied with valuable notes. 



' Geographie Botanique,' torn. iv. p. 488. 



