9 8 Flowers and their Unbidden Guests. 



though there are at the same time indisputable cases 

 where they prevent animals from crawling up to the 

 flowers from helow. Such, for example, is the case in 

 8empervivum arachnoideum L., and other nearly allied 

 species, where the radical rosette, the stem, and the 

 sessUe leaves, are covered over with a web of such 

 trichomes ; such also in many Compositse, where similar 

 formations are found on leaves and stem, sometimes 

 (e.g. Cirsiwm eriophorum) as high even as the invo- 

 lucrum. Many small wingless animals are utterly 

 debarred from any possible progress by such trichomes; 

 many are caught and held in the tangle of fibres as 

 securely as in a spider's web, and once in can never 

 again get free. 



6. Access to Flowers impeded by Parts of the Plant, and 

 especially Parts of the Flower, being bent, or dilated, 

 or crowded together. 



In all cases where the nectar is abundant, and 

 yet is not protected by any of the hair-like structures 

 described in the preceding section, one may reckon 

 with almost certain confidence on finding such pro- 

 tection afforded by the peculiar position or formation 

 of some or other parts of the flower. These, to 

 mention the main features, are either curved, or dilated, 

 or crowded together; and so form grooves, tubes, 

 tubercles, saccular recesses, chambers, in such endless 



