| Fig. 92.—Digitate-veined Peltate Leaf of Nasturtium. | Fig. 93.—Pinnately Compound Leaf of Ash. |
It is customary to speak of a leaf as compound only when the parts or branches are completely separate blades, as when the division extends to the midrib (Figs. [90], [93], [94, 95]). The parts or branches are known as leaflets. Sometimes the leaflets themselves are compound, and the whole leaf is then said to be bi-compound or twice-compound (Fig. [90]). Some leaves are three-compound, four-compound, or five-compound. Decompound is a general term to express any degree of compounding beyond twice-compound.
| Fig. 94.—Digitately Compound Leaf of Raspberry. | Fig. 95.—Poison Ivy. Leaf and Fruit. |
Leaves that are not divided as far as to the midrib are said to be:
Fig. 96.—Lobed Leaf of Sugar Maple.
lobed, if the openings or sinuses are not more than half the depth of the blade (Fig. [96]);
cleft, if the sinuses are deeper than the middle;
