Order 4. Cannabaceæ. The plants which belong to this order are aromatic herbs, either annuals or perennials, without latex. Leaves palminerved, and more or less divided, hispid, and with free, persistent stipules. Flowers always diœcious; ♂-flowers in panicles, formed of dichasia, passing over into uniparous scorpioid cymes. They differ from the Nettles, particularly in the 5-leaved perianth of the ♂-flower, the 5 stamens (Fig. [346–351]) with filaments erect in the bud, and in the ♀-flower by the small, entire, cup-like perianth, which surrounds the base of the ovary (Fig. [346], p. [352]). The ovary has two styles, or one divided into two, with two stigmas and a pendulous, curved ovule (Fig. [346] B, [352] B); the fruit is a nut; the embryo is curved (Hemp, Fig. [353]), or rolled (Hop, Fig. [349]), without endosperm.
Fig. 346.—Diagram of male and female flowers of the Hop and Hemp: b the bract, p the perianth. The position of the embryo is indicated.
Only 2 genera with 3 species (Asiatic), of which two are cultivated.—Humulus lupulus (Hop, Figs. [347–349]) is a twining, perennial plant, twisting to the right, with opposite, palmilobed, rough leaves, and large, interpetiolar stipules. The ♀-flowers are situated in closely-flowered, cone-like, compound inflorescences, with ultimately large, thin, imbricate floral-leaves (Fig. [348]) which bear the yellow, glandular hairs, containing lupulin. This inflorescence is made up as follows:—The most external floral-leaves are situated in pairs, and are the persistent stipules of a leaf, the blade of which has become suppressed, or in any case is rudimentary. Such a pair of stipules supports 4 (2–6) flowers in a double uniparous cyme, whose central axis does not develope into a flower. The bracts of these flowers (bracteoles of the partial inflorescence) become, at maturity, very large, spathe-like, and, together with the stipules, produce a cone-like appearance.
Fig. 347–348.—Humulus lupulus: 347, twining stem; 348, branch with strobiles.
Cannabis sativa (Hemp, Figs. [350–353]) is an East Indian herb, with palmilobed leaves, and differs from the Hop in being annual, erect, and in having its leaves opposite at the base and scattered above. The ♀-inflorescence is not cone-like as in the Hop, but the flowers are similar in construction. The main difference is to be found in the axillary shoot, which was suppressed in the Hop, and is in the Hemp developed into a leaf-bearing shoot which on each side bears only one ♀-flower, and in the fact that the bracts are not so strongly developed.
The “Hops” (the female inflorescences) are used in brewing, and medicinally on account of the yellow glands which contain lupulin. The Indian variety of Cannabis sativa contains an abundance of glandular hairs and resin. The withered inflorescences are used in medicine and are officinal. The bast of the stems of the Hemp is also used and the fat oil of the seeds. In Oriental countries the entire plant is used in the preparation of an intoxicating drink (haschisch), the narcotic material being found in the glandular hairs.
