143. Correspondingly in the lower row, of palmately veined leaves, the first is palmately lobed, the second palmately cleft, the third palmately parted, the fourth palmately divided. Or, in other language of the same meaning (but now less commonly employed), they are said to be digitately lobed, cleft, parted, or divided.
144. The number of the divisions or lobes may come into the phrase. Thus in the four last named figures the leaves are respectively palmately three-lobed, three-cleft (or trifid), three-parted, three-divided, or better (in Latin form), trisected. And so for higher numbers, as five-lobed, five-cleft, etc., up to many-lobed, many-cleft or multifid, etc. The same mode of expression may be used for pinnately lobed leaves, as pinnately 7-lobed, -cleft, -parted, etc.
145. The divisions, lobes, etc., may themselves be entire (without teeth or notches), or serrate, or otherwise toothed or incised; or lobed, cleft, parted, etc.: in the latter cases making twice pinnatifid, twice palmately or pinnately lobed, parted, or divided leaves, etc. From these illustrations one will perceive how the botanist, in two or three words, may describe any one of the almost endlessly diversified shapes of leaves, so as to give a clear and definite idea of it.
[146.] Compound Leaves. A compound leaf is one which has its blade in entirely separate parts, each usually with a stalklet of its own; and the stalklet is often jointed (or articulated) with the main leaf-stalk, just as this is jointed with the stem. When this is the case, there is no doubt that the leaf is compound. But when the pieces have no stalklets, and are not jointed with the main leaf-stalk, it may be considered either as a divided simple leaf, or a compound leaf, according to the circumstances. This is a matter of names where all intermediate forms may be expected.
147. While the pieces or projecting parts of a simple leaf-blade are called Lobes, or in deeply cut leaves, etc., Segments, or Divisions, the separate pieces or blades of a compound leaf are called Leaflets.
148. Compound leaves are of two principal kinds, namely, the Pinnate and the Palmate; answering to the two modes of veining in reticulated leaves, and to the two sorts of lobed or divided leaves ([141]).
Fig. 156-158. Pinnate leaves, the first with an odd leaflet (odd-pinnate); the second with a tendril in place of uppermost leaflets; the third abruptly pinnate, or of even pairs.
149. Pinnate leaves are those in which the leaflets are arranged on the sides of a main leaf-stalk; as in Fig. [156-158]. They answer to the feather-veined (i. e. pinnately-veined) simple leaf; as will be seen at once on comparing the forms. The leaflets of the former answer to the lobes or divisions of the latter; and the continuation of the petiole, along which the leaflets are arranged, answers to the midrib of the simple leaf.