and issuing either from the branches or immediately from 

 the stem or root. 



All leaves, however, are not thin and flat in their configuration, or 

 of an uniform green colour ; for the leaves of the aloe and common 

 house-leek are thick and fleshy ; the leaves of the beet are of a dark 

 dull purple j and the leaves of the canary reed-grass are variegated 

 with stripes of white and green. 



2. Leaves are generally divided into two sets, viz. 

 those which are called sessile, and those which are deno- 

 minated petiolute. 



When they spring immediately from the root by a broad expansion, 

 as in the hyacinth, or united to the stem or branch by an immediate 

 approximation with their base, they are said to be sessile (bb, F. 31, 

 and6); bntif the expansion ofthe leaf is supported on a foot stalk, 

 or petiole, (a,F. 40) as in the geranium, they are termed petiolate. 



3. In addition to the division of leaves into sessile 

 leaves and petiolate, they are also divided into simple 

 leaves and compound leaves. 



A leaf is m/>/ewben it rests,by itself, upon one common leafstalk, 

 and consists of a regular expansion, as in the primrose, geranium, &c. 

 and compound when it consists of two or any greater number of leaf- 

 lets, connected by one common leaf-stalk, as in the rose, elcjer, &c. 



4. The characteristic points connected with the gene- 

 rality of leaves (and leaflets) of the petiolate kind, are 

 nine in number ; for in the elements of botany, they are 

 usually described as having an upper and an under sur- 

 face, a mid-rib and lateral nerves, a base, an apex, a disk, 

 a margin, and afoot-stalk or petiole. 



To understand these peculiar parts, you have only to select a leaf 

 of the cherry-tree, and you will find the upper surface to be of a dark 



