168 A COMPENDIUM OF 
FOLIA ET FOLIOLA; LEAVES AND 
LEAFLETS. 
These organs of vegetable life form an im- 
portant part in the economy of the plant or tree. 
Leaves are formations produced by the expan- 
sion of the bark at the nodes of thestem. Their 
purpose is fourfold: first, for adornment; sec- 
ondly, for purifying agents for the growth of 
the plant; thirdly, for the absorption of gases 
hurtful to the animal world; and, fourthly, as 
remedies for the cure of disease. Leaves as- 
sume many shapes, such as cordate, obcordate, 
lanceolate, ovate, obovate, oval, and reniform; 
with their edges serrated, dentated, repand, 
crenate, and entire; the surfaces or blades of 
leaves are found glabrous (without hairs), pu- 
bescent, vilous, tomentous, scabrous, smooth etc. 
The shapes of leaves and leaflets depend upon 
the framework. ‘This is composed of midribs, 
veins, and veinlets. Some leaves are closely 
netted with veins and veinlets, and present a 
