Viscid Stipules and Bracts. 59 



able; and they are consequently kept off by the viscid 

 matter which the glandular trichomes on the sessile 

 leaves and on the leaf-stalks secrete in abundance. 



The stipules confer this kind of protection even more 

 frequently than the leaves themselves, and for this 

 ofi&ce they are admirably suited by their situation at 

 the base of the leaf-stalk and around the stem. A 

 large number of plants are, as is well known, furnished 

 with highly developed glandular trichomes upon their 

 stipules ; and these stipules with their viscid secretions 

 are placed directly across the path of upward-crawling 

 animals, in such a position as to render it quite 

 impossible to get round them. 



Yet more frequently it is the involucres and bracts 

 of the inflorescence that are provided with colleters.^ 

 For instance, the foliar organs that stand at the bottom 

 of the flower-bearing shoot of" Acer plataTwides L. 

 have their under surface, that is, the side which 

 is presented to any up-crawling animal, completely 

 covered with a layer of viscid matter ; and the same is 

 true of the small leaves that invest the catkin-bear- 

 ing shoots of Salix pentandra L. But the bracts 

 which are most frequently converted, in virtue of 

 their colleters, into a protective viscid screen are those 

 which form the involucrum of Compositse, over which 



* [Colleter is the name given by Hanstein to the glandular hairs 

 which coat the leaf -buds of many plants with a gummy secretion or 

 with blastocol, i.e. gum-mucilage and resin.— Editoe.] 



