ORDER CLXXI.—ULMACEÆ.
The principal genera are the Elm (Ulmus), the Nettle-tree (Celtis), and the Zelkoua-tree (Planera). The flowers, though very small, are pretty, from their opening in clusters before the leaves; and each has four stamens, with dark purple anthers, and is furnished with dark brown bracts. The fruit is a utricle, having a single seed, encircled by a broad thin transparent membrane. The leaves are rough, and their sides are unequal at the base. The bark of Elm trees is rough and deeply furrowed; and the roots spread, instead of penetrating deeply into the ground like those of the Oak.
ORDER CLXXII.—PIPERACEÆ.
The species are generally climbing plants with perfect flowers, which are produced in spikes, and are succeeded by one-seeded berries. The genus Piper contains the common Pepper (P. nigrum), the Betel (P. Betel), and several other species.
ORDER CLXXIII.—JUGLANDACEÆ.—(See Chap. XI. P. [176].)
The male and female flowers are distinct, but on the same plant. The male flowers are pro duced on long thick anthers, and each consists of a scale-like calyx enclosing numerous stamens; the female flowers are two or more together, and each consists of a scale-like calyx, enclosing a one-celled ovary. The fruit is a drupe, that is, it consists of a fleshy husk enclosing a nut. The embryo fills the whole seed; and the cotyledons are fleshy, two-lobed, and wrinkled. There are only two genera, the Walnut (Juglans), the male catkins of which are produced singly, and the Hickory (Carya), the male catkins of which are in clusters.
ORDER CLXXIV.—AMENTACEÆ.—(See Chap. XI. P. [174]).