, _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).

[Illustration: 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.

150. Three sorts of pinnate leaves are here given. Fig. 156 is _pinnate
with an odd_ or _end leaflet_, as in the Common Locust and the Ash. Fig.
157 is _pinnate with a tendril at the end_, in place of the odd leaflet,
as in the Vetches and the Pea. Fig. 158 is evenly or _abruptly pinnate_,
as in the Honey-Locust.

[Illustration: Fig. 159. Palmate (or digitate) leaf of five leaflets, of
the Sweet Buckeye.]

151. _Palmate_ (also named _Digitate_) leaves are those in which the
leaflets are all borne on the tip