

POLLINATION IN LINARIA 



WITH SPECIAL REFERENCE TO CLEISTOGAMY 



E. J. Hill 



(with pour figures) 

 i. pollination by insects 



The genus Linaria furnishes examples of adaptations to both 

 cross- and self-pollination. Of the sixteen species given in Knuth's 

 Handbuch der Blutenbiologie, nine are said to be visited by insects 

 and may be pollinated by them. One, L. origanifolia DC, as 

 observed by MacLeod, is adapted to insects, but was not seen to use 

 them. Four or five seem to be restricted to self-pollination, and all 

 can also employ it. Some produce cleistogamous flowers, and as far 

 as these can be of service, are compelled to pollinate in this way. 

 L. vulgaris Mill, (as Antirrhinum Linaria L.) was the first to be 

 observed and described. This was by Ch. K. Sprengel in his 

 book on the relations of flowers and insects, published in 1793. It 

 was one of the first with which Darwin experimented when preparing 

 the material for his work on the effects of cross- and self-fertilization 

 in the vegetable kingdom. An unexpected presentation of vigor in 

 one of two beds of this species, planted for the purpose of determining 

 some points regarding inheritance, led him to trials with this and other 

 plants on the results of pollination. 



Linaria is called a mellitophilous genus, since bees are the princi- 

 pal agents in the process, though in some species several other insects, 

 especially Lepidoptera, share in the work. The honey, secreted by 



where it is stored and awaits the visits of insects with a proboscis 

 long enough to reach it. It is therefore well adapted to visitors of 

 this kind belonging to the class called Eutropic by Loew. 1 The 

 two pairs of anthers are placed at different heights, with the slender 

 style and the stigma in the space between. These are brushed by the 

 back of a bee crowding in to get the nectar in the spur, or by the 



some 



1 Loew, Einfiihrung in die Bliithenbiologie 342, 345. 1895. 

 Botanical Gazette, vol. 47] 



s 



454 



