=Kinds.=--Leaves are =simple= or unbranched (Figs. 88, 89), and =compound= or branched (Fig. 90). The method of compounding or branching follows the mode of veining. The veining, or =venation=, is of two general kinds: in some plants the main veins diverge, and there is a conspicuous network of smaller veins; such leaves are =netted-veined=. They are characteristic of the dicotyledons. In other plants the main veins are parallel, or nearly so, and there is no conspicuous network; these are =parallel-veined= leaves (Figs. 89, 102). These leaves are the rule in monocotyledonous plants. The venation of netted-veined leaves is =pinnate= or feather-like when the veins arise from the side of a continuous midrib (Fig. 91); =palmate= or =digitate= (hand-like) when the veins arise from the apex of the petiole (Figs. 88, 92). If leaves were divided between the main veins, the former would be pinnately and the latter digitately compound. [Illustration: FIG. 91.--COMPLETE LEAVES OF WILLOW.] [Illustration: FIG. 92.--DIGITATE-VEINED PELTATE LEAF OF NASTURTIUM.] [Illustration: 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. [Illustration: FIG. 94.--DIGITATELY COMPOUND LEAF OF RASPBERRY.] [Illustration: FIG. 95.--POISON IVY. LEAF AND FRUIT.] [Illustration: FIG. 96.--LOBED LEAF OF SUGAR MAPLE.] Leaves that are not divided as far as to the midrib are said to be: =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; =parted=, if the sinuses reach two thirds or more to the midrib (Fig. 97); =divided=, if sinuses reach nearly or quite to the midrib. The parts are called =lobes=, =divisions=, or =segments=, rather than leaflets. The leaf may be pinnately or digitately lobed, parted, cleft, or divided. A pinnately parted or cleft leaf is sometimes said to be =pinnatifid=. [Illustration: FIG. 97.--DIGITATELY PARTED LEAVES OF BEGONIA.] Leaves may have one or all of three parts--=blade=, or expanded part; =petiole=, or stalk; =stipules=, or appendages at the base of the petiole. A leaf that has all three of these parts is said to be =complete= (Figs. 91, 106). The stipules are often green and leaflike and perform the function of foliage, as in the pea and Japanese quince (the latter common in yards). [Illustration: FIG. 98.--OBLONG-OVATE SESSILE LEAVES OF TEA.]