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 produced 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). The male flowers are in catkins, and the fruit of most of the genera is, when ripe, partially or wholly enclosed in a cup-like involucre, formed by the adhesion of the numerous bracts. ORDER CLXXV.—HAMAMELIDEÆ. This order has been already inserted, p. 380. ORDER CLXXVI.—EMPETREÆ. Little heath-like plants, with small flowers and showy berries. The Crowberry, _Empetrum nigrum_, is very common in Scotland on heaths. ORDER CLXXVII.—CONIFERÆ. (SEE CHAP. XII. P. 205.) The male and female flowers are both produced in catkins, and both consist only of scales. The pollen of the male flowers is very abundant, and is discharged freely in fine weather. The female flowers form cones, consisting of numerous scales, at the base of each of which are two winged seeds. The timber abounds in resin. ORDER CLXXVIII.-CYCADEÆ. (SEE CHAP. XII. P. 229.) These singular plants have thick timber-like trunks, yet they can hardly be called trees, as they increase in height by a single terminal bud. The leaves are pinnate, and they unroll, when they expand, like those of the ferns. The male flowers are in cones, and the female ones either in cones, or produced on the margin of contracted leaves. The principal genera are Zamia and Cycas, and one species of the latter yields a kind of sago; the true kind being a product of a species of Palm. CHAPTER III. PHANEROGAMOUS PLANTS.—MONOCOTYLEDONEÆ. All the trees belonging to this division are natives of tropical countries; and they, as well as all the herbaceous plants belonging to it, are distinguished by the veins of their leaves being never branched, but principally in parallel lines. These plants are re-divided into those with a perianth, which are called the Petaloideæ, and in which are included the Orchidaceæ and the bulbous-rooted plants; and those without a perianth, which are called Glumaceæ, and in which are included the grasses, and sedges. § I.—PETALOIDEÆ. ORDER CLXXIX.—HYDROCHARIDEÆ.—THE FROG’S BIT TRIBE.