FORM
As to general form, or outline, leaves are:—
Those broadest in the middle—
peltate, or shield-shaped, when rounded, with the stem attached to the center, or near it—as in the garden nasturtium;
orbicular, when circular in outline, or nearly so;
oval, when having a flowing outline, with the breadth considerably more than half the length, and both ends alike;
elliptical, when having a flowing outline, twice or thrice as long as broad, and both ends alike;
oblong, when nearly twice or thrice as long as broad;
linear, when narrow, several times longer than wide, and of about the same width throughout;
acerose, when needle-shaped—like the Pine.
Those broadest at the base—
deltoid, when having the triangular shape of the Greek letter delta;
ovate, when having an outline like the section of a hen's-egg, the broader end downward;
lanceolate, or lance-shaped, when several times longer than broad, and tapering upward, or both upward and downward;
subulate, when shaped like an awl;
cordate, when ovate, with a heart-shaped base;
reniform, when like the last, only rounder and broader than long;
auriculate, when having a pair of small blunt projections, or ears, at the base;
sagittate, or arrow-shaped, when those ears are acute and turned downward, the body of the leaf tapering upward;
hastate, or halberd-shaped, when the ears or lobes point outward.
Those broadest at the apex—
obovate, when inversely ovate;
oblanceolate, when inversely lanceolate;
spatulate, when rounded above, and long and narrow below, like a druggist's spatula;
cuneate, or wedge-shaped, when broad above, tapering by straight lines to an acute base;
obcordate, when inversely cordate.
Sometimes no one of the above terms will describe a leaf, and it becomes necessary to combine two of them; as, linear-spatulate, ovate-lanceolate, etc.