92 BUDS AND STIPULES 



In certain species such hairs contain an acrid liquid, 

 as in the Common Nettle (Urtica dioica). 



Protection by stiff hairs occurs also among the La- 

 biatce in Galeopsis (6r. Tetrahit and versicolor) ; among 

 the Boraginece in Ecliium, Lycopsis, Borago, Anchusa ; 

 among the Loasece in Loasa ; among the Leguminosce in 

 Mucuna ; Saxifragece in Davidsonia ; MalpigJiiaceoB in 

 Malpighia, &c. 



These hairs constitute, however, a protection to the 

 plant as a whole, rather than to the buds specially. 



Protection ly Gum, Resin, or Turpentine 



In other cases buds are protected by gummy or 

 resinous secretions, as in the Horse Chestnut (^Esculus), 

 the Poplar (Populus), Hazel Nut (Gorylus\ Honeysuckle 

 (Lonwercb)^ Currant (Ribes), Lilac (Syringa), Hornbeam 

 (Carpinus), Elder (Sambucus), and Alder (Alnus\ in 

 many herbaceous plants (Viola, Helianthus, Salvia), and 

 most Conifers. 



The gum is often confined to the outer surface, the 

 interspaces between the leaves being filled by hairs. 



The gum or resin is secreted by hairs, by glands, by 

 leaf-teeth, or by the general epidermis. The gum cells 

 are generally developed early, and are short-lived. 

 The secretion lessens transpiration, and in many cases 

 also serves to protect the young leaves from insects 

 and other animals. Smaller insects would get legs 



