124 STKUCTUKAL BOTANY. [105,106. 



such a coat may also be lanuginose, woolly ; tomen- 

 tose, matted like felt ; or floccose, in soft, fleecy tufts. 



313. Thinly scattered hairs render the surface hir- 

 sute when they are long ; pilose when short and soft ; 

 hispid when short and stiff. The surface will be setose 

 when beset with bristly hairs called setce ; and spinose 

 when beset with spines, as in the Thistle and Horse- 

 nettle. Leaves may also be armed with stinging hairs 

 which are sharp and tubular, containing a poisonous 

 fluid, as in Nettles and Jatropha stimulans (503). 



314. A pruinose surface is covered with a bluish- 

 white waxy powder, called bloom, as in the Cabbage ; 

 and a punctate leaf is dotted with colored points or 

 pellucid glands. 



315. In texture leaves may be membranous, or 

 coriaceous (leathery), or succulent (fleshy), or scarious 

 (dry), rugose (wrinkled), etc., which terms need only 

 to be mentioned. 



316. Double terms. The modifications of leaves are almost endless. 

 Many other terms are defined in the glossary, yet it will often be found neces- 

 sary in the exact description of a plant to combine two or more of the terms 

 defined in order to express some intermediate figure or quality ; thus ovate- 

 lanceolate, signifying a form between ovate and lanceolate, etc. 



317. The Latin preposition sub (under) prefixed to a descriptive term 

 denotes the quality which the term expresses, in a lower degree, as subsessile, 

 nearly sessile, subserrate, somewhat serrate. 



CHAPTER XXIII. 



TRANSFORMATIONS OF THE LEAF. 



318. Hitherto we have considered the leaf as foli- 

 age merely constituted the fit organ of aeration by 

 its large expansion of surface. This is indeed the 

 chief, but not the only aspect in which it is to be 

 viewed- The leaf is a typical form ; that is, a type, or 



