12 INTRODUCTION. 



period, and their anthers, which never open or dehisce, 

 generally contain pulpy matter instead of pollen. On 

 some female trees, however, I found a few anthers con- 

 taining pollen-grains apparently sound. On the male 

 trees most of the flowers include pistils, but these like- 

 wise drop off at an early period; and the ovules, which 

 ultimately abort, are very small compared with those 

 in female flowers of the same age. 



Of the other or monoecious sub-group of polygamous 

 plants, or those which bear hermaphrodite, male, and 

 female flowers on the same individual, the common 

 Maple (Acer campestre) offers a good instance; but Lecoq 

 states * that some trees are truly dioecious, and this 

 shows how easily one state passes into another. 



A considerable number of plants generally ranked 

 as polygamous exist under only two forms, namely, as 

 hermaphrodites and females; and these may be called 

 gyno-dicecious, of which the common Thyme offers a 

 good example. In my seventh chapter I shall give 

 some observations on plants of this nature. Other spe- 

 cies, for instance several kinds of Atriplex, bear on the 

 same plant hermaphrodite and female flowers; and these 

 might be called gyno-moncecious, if a name were desira- 

 ble for them. 



Again there are plants which produce hermaphro- 

 dite and male flowers on the same individual, for in- 

 stance, some species of Galium, Veratrum, &c.; and 

 these might be called andro-moncecious. If there 

 exist plants, the individuals of which consist of herma- 

 phrodites and males, these might be distinguished 

 as andro-dicecious. But, after making inquiries from 

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

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



* ' Geographic Botanique,' torn. v. p. 367. f Ibid. torn. iv. p. 488. 



