Fig. 340.—Diagram of ♂-and ♀-flowers of Urtica dioica.
Fig. 341.—Parietaria diffusa; hermaphrodite flower: a in the female, b at the commencement of the male stage; the stigma has fallen off, but the anthers have not yet dehisced.
Wind-Pollinated. The pollen is shot out of the anthers, when they spring forward, and is caught by long stigmatic hairs. Parietaria diffusa is protogynous (Fig. [341]).
500 species; chiefly in the Tropics, although the few species which occur in Europe are represented by a much larger number of individuals.—Uses. The bast of the native species Urtica dioica and urens, of U. cannabina (Siberia), etc.; of Boehmeria nivea “Ramié” and “China-grass” (from Sunda Is., China), and others, is used in the manufacture of muslin.
Order 3. Moraceæ (Mulberries). Nearly all trees or shrubs, seldom herbs, generally with latex. The leaves are scattered, and not infrequently lobed. The flowers are unisexual (monœcious or diœcious) and arranged in catkin- or capitulum-like, compound inflorescences. Perianth-leaves 2–6, generally 4, with an equal number of stamens opposite to them, as in the Nettles. The ovary is 1–seldom 2-locular, and has 2 stigmas (it is thus formed from 2 carpels) seldom only one style with one stigma. One ovule in each loculus, more or less curved, and pendulous; micropyle directed upwards. Fruit usually a drupe. The embryo is generally curved inside the fleshy endosperm, or it is exendospermous.
Fig. 342.—Morus alba ♂ flower (6/1).
