rincipal shapes, and to define them rather precisely,
since they afford easy marks for distinguishing species. The same terms
are used for all other flattened parts as well, such as petals; so that
they make up a great part of the descriptive language of Botany. It will
be a good exercise for young students to look up leaves answering to
these names and definitions. Beginning with the narrower and proceeding
to the broadest forms, a leaf is said to be

_Linear_ (Fig. 115), when narrow, several times longer than wide, and of
the same breadth throughout.

_Lanceolate_, or _Lance-shaped_, when conspicuously longer than wide,
and tapering upwards (Fig. 116), or both upwards and downwards.

_Oblong_ (Fig. 117), when nearly twice or thrice as long as broad.

_Elliptical_ (Fig. 118) is oblong with a flowing outline, the two ends
alike in width.

_Oval_ is the same as broadly elliptical, or elliptical with the breadth
considerably more than half the length.

_Ovate_ (Fig. 119), when the outline is like a section of a hen's egg
lengthwise, the broader end downward.

_Orbicular_, or _Rotund_ (Fig. 132), circular in outline, or nearly so.

[Illustration: Fig. 121, oblanceolate; 122, spatulate; 123, obovate; and
124, wedge-shaped, feather-veined, leaves.]

135. A leaf which tapers toward the base instead of toward the apex may
be

_Oblanceolate_ (Fig. 121) when of the lance-shaped form, only more
tapering toward the base than in the opposite direction.

_Spatulate_ (Fig. 122) when more rounded above, but tapering thence to a
narrow base, like an old-fashioned spatula.

_Obovate_ (Fig. 123) or inversely ovate, that is, ovate with the
narrower end down.

_Cuneate_ or _Cuneiform_, that is, _Wedge-shaped_ (Fig. 124), broad
above and tapering by nearly straight lines to an acute angle at the
base.

[Illustration: Fig. 125, sagittate; 126, auriculate; and 127,
halberd-shaped or hastate leaves.]

136. =As to the Base=, its shape characterizes several forms, such as

_Cordate_ or _Heart-shaped_ (Fig. 120, 129), when a leaf of an ovate
form, or something like it, has the outline of its rounded base turned
in (forming a notch or _sinus_) where the stalk is attached.

_Reniform_, or _Kidney-shaped_ (Fig. 131), like the last, only rounder
and broader than long.

_Auriculate_, or _Eared_, having a pair of small and blunt projections,
or _ears_, at the base, as in one species of Magnolia (Fig. 126).

_Sagittate_, or _arro