26 LEAVES. 



Simple Leaves. 



A SIMPLE LEAF, (folium simplex^) is one whose foot- 

 stalk is terminated by a single expansion. See pi. 5. 



Observation. Whose divisions however deep do not reach the 

 mid-rib. The mid-rib of a leaf is the principal prolongation of the 

 foot-stalk, which usually runs longitudinally through the middle 

 of it. 



Simple leaves are either 



UNDIVIDED, (Integra} having no divisions or lobes. 

 Ex. Grasses ; or 



LOBED, (lobata) divided into segments. Ex. Cranes- 

 bill, Geranium, and Crowfoot, Ranunculus. 



Simple leaves are described by their form, surface, c. 



Reference. For the definition of a compound leaf, see sec- 

 tion VIII. 



III. Form. 



1. ORBICULAR LEAF, (folium orbiculalum.*) PI. 5, 

 fig. 1. A circular leaf $ having its length arid breadth 

 equal. 



2. ROUNDISH, (subrotundum^) PI. 5, fig. 2. Ap- 

 proaching to the circular form. Ex. lloundleaved 

 Wintergreen, Pyrola rotundifolia. 



S. OVATE, (orrchwi.) PL 5, fig. S. Egg-shaped ; 

 the hase round and broader than the extremity. 



Observation. A very common form of leaves. 



4. OBOVATE, (obmatum.} PI. 5, fig. 4. Ovate, 

 with the broad end uppermost. Ex. Clethra aln'tfolia. 



5. ELLIPTICAL, (ellipticum.} PI. 5, fig. 5. Oval ; 

 of the form of an ellipsis, longer than broad, with the 

 curve of both ends equal. Ex. Solomon's Seal, Con- 

 vailaria. 



6. OBLONG, (oblongwri) three or four times longer 

 than broad. 



Observation. This term is used with great latitude, and serves 

 chiefly in a character to contrast a leaf which has a variable, or 

 not a very decided form., with others that are precisely round, 

 ovate, linear, &c. 



