LECT. IX.] LEAVES. 511 



ceous denotes. The terms scariose (scariosum), and 

 chartaceous (chartaceum, papyraceum) r are given 

 to varieties of the membranous leaf; the first im- 

 plying that it is dry, or apparently sapless, and 

 somewhat translucent ; the second, that it re- 

 sembles paper, as in Draco terminalu. Leathery 

 (coriaceum) implies that the leaf is thick, tough, 

 and elastic; as in the Mistletoe, Viscum album, 

 Changeable Hydrangea, Hydrangea hortensis, &c. : 

 and rigid (rigidum), that it is hard, with little elas- 

 ticity, as in Butcher's broom, Ruscus aculeatus, 

 Scotch fir, Pinus sylvestris, &c. Fleshy (carnosum) 

 denotes that the leaf is thick, and consists chiefly 

 of a juicy but firm cellular parenchyma, as in 

 Houseleek, Sempervivum tectorum ; and succulent 

 (succulentum), that the pulp is laxer and more 

 juicy, as in Mesembryanthemum echinatum, &c. 

 Mirbel says the consistence of the fleshy leaf is 

 that of the Apple ; of the succulent that of the 

 Plum *. 



As all the characteristics of leaves, which I 

 have yet described, relate to the expansion, they 

 are consequently peculiar to simple leaves only, or 

 to the individual leaflets of compound leaves. Be- 

 fore detailing those common to both descriptions 

 of leaves, it is requisite to understand the pecu- 



* Elemens de Phys. veg. iii. p. 642. 



