HETEROGAMY AND AUTOGAMY. 199 



requiring insect agency and self-ferfcilisation or autogamy ; 

 as well as in the majority of flowers which are too incon- 

 spicuous to invite insects at all, or which never expand. The 

 series of such flowers tex'minates in perfect and perpetual 

 cleistogamy. 



The first condition, or Protandry, does not now require 

 special discussion or illustration ; as it is the jDrevailing one 

 ill most conspicuous flowers : though it must be distinctly 

 borne in mind tha,t the exceptions are rare in which a flower 

 cannot fertilise itself at some period or other before it fades ; 

 even though a large order, as 0)xh{dece, may furnish many 

 examples. 



Protog'yny may arise from several causes. Milller has 

 mentioned about twenty species of plants iri-espective of the 

 Grasses which are more or less decidedly protogynoua ; and 

 what one notices is that many are Alpine species of genera 

 which have other species dispersed elsewhere that are homo- 

 gamous or protandrous. Thus Anemone alpina is protogynous, 

 but A. NarcissifoUa is protandrous. Jxanunculus montaniis, B. 

 parnassifolius, R. pyrenceus are all protogynous. These may 

 be compared with the smaller-flowered forms of R. aquatilis 

 which are homogamous ; but B. flammula, B. acris, B. repens 

 and B. hulbosus are protandrous with the outermost stamens 

 only. Thus, this genus supplies a progressive series. Other 

 protogynous and mountain species are Dnjas octopetala, 

 species of Saxifrage, as 8. androsacea and 8. muscoides, and 

 S. 8eguieri: but Miiller found *S^. oppositifolia and 8. tridac- 

 tylites to be sometimes feebly protandrous, at others proto- 

 gynous. On the other hand, 8. rotundifoUa, 8. aizoides, etc. 

 are protandrous. Loiseleuria procumbens, Trientalis Europcea, 

 Bartsia alpina, Hutchinsia alpina, and Thalictrum alpinum 

 are all protogynous. 



Secondly, a group of plants, the flowers of which have 



