60 



OP THE COMPOUND LEAF. 



283. Pointed leaves. In regard to the termination of a leaf at its 

 apex, it may be acuminate, ending with a long, tapering point ; cuspi- 

 date, abruptly contracted to a sharp, slender point ; mucronate, tipped 

 with a spiny point ; acute, simply ending with an angle ; obtuse, rounded 

 at the point. 



284. Pointless leaves. Or the leaf may end without a point, 

 being truncate, as if cut square off ; retuse, with a rounded end slightly 

 depressed where the point should be ; emarginate, having a small notch 

 at the end ; obcordate, inversely heart-shaped, having a deep indentation 

 at the end. 



OF THE COMPOUND LEAF. 



285. Theory. If we conceive of a simple leaf becoming a com- 

 pound one, on the principle of " deficiency of tissue between the veins," 

 it will be evident tliat the same forms of venation are represented by 

 the branching petioles of the latter as by the veins of the former. 

 The number and arrangement of the parts will therefore in like man- 

 ner correspond with the mode of venation. 



286. Leaflets. The divisions of a compound leaf are called leaflets, 

 and the same distinction of outline, margin, &c, occur in them as in 

 simple leaves. The petiohdes of the leaflets may or may not be articu- 

 lated to the main petiole, or rachis, as it is called. 



15T 161 159 160 158 



Compound leaves. 157, Trifolium repens. 158, Desmodium rotundifolium. 160, Glotidium. 

 161, Cassia. 159, Agrimonia. 



287. Pinnately compound. From the pinnate-veined arrangement 

 we may have the pinnate leaf, where the petiole (midvein) bears a row 

 of leaflets on each side, either sessile or petiolulate, generally equal in 



