12 INTRODUCTION. 



was in function a male. The separation of the sexes, 

 however, is not complete in the Ash ; for the female 

 flowers include stamens, which drop off at an early 

 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 monoicous 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-dioecious, of which the common Thyme offers a 

 good example. In my seventh chapter I shall give 

 some observations on plants of this nature. Other 

 species, for instance several kinds of Atriplex, bear on 

 the same plant hermaphrodite and female flowers ; and 

 these might be called gyno-monoacious, if a name were 

 desirable for them. 



Again there are plants which produce hermaphrodite 

 and male flowers on the same individual, for in- 

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

 these might be called andro-monoecious. If there 

 exist plants, the individuals of which consist of her- 

 maphrodites and males, these might be distinguished 



* ' nongraphic Botanique,' torn. v. p. 307. 



