Fig. 97.—Digitately Parted Leaves of Begonia.
parted, if the sinuses reach two thirds or more to the midrib (Fig. [97]);
divided, if the 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.
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 leaf-like and perform the function of foliage as in the pea and the Japanese quince (the latter common in yards).
Fig. 98.—Oblong-ovate Sessile Leaves of Tea.
Leaves and leaflets that have no stalks are said to be sessile (Figs. [98], [103]), i.e. sitting. Find several examples. The same is said of flowers and fruits. The blade of a sessile leaf may partly or wholly surround the stem, when it is said to be clasping. Examples: aster (Fig. [99]), corn. In some cases the leaf runs down the stem, forming a wing; such leaves are said to be decurrent (Fig. [100]). When opposite sessile leaves are joined by their bases, they are said to be connate (Fig.[ 101]).
Fig. 99.—Clasping Leaf of a Wild Aster.