diœcious flowers of Sheep-sorrel (Rumex Acetosella and R. acetosa). Rhubarb of greengrocers is the succulent acid petiole of a species of Rheum. Eastern species of the same genus afford the root used in medicine as Rhubarb. Buckwheat (Polygonum Fagopyrum) has been long cultivated in temperate countries for its farinaceous seeds, of which a useful bread is made. It is planted in England for feeding game and poultry. DISTRIBUTION.-Chiefly confined to the Old World, and most numerous in Australia and at the Cape of Good Hope.-One British genus, species 2. Shrubs. Ovary I-celled, with I pendulous ovule. Type-Spurge Laurel (Daphne Laureola). An erect little-branched shrub, with shining evergreen entire leaves, and clustered greenish flowers. OBSERVE the tenacious liber-layer of the bark, characteristic of the Family the highly-coloured perianth of some garden and greenhouse genera. The berries of Mezereon (D. Mezereum) are poisonous, and those of Spurge Laurel are also said to be poisonous to all animals excepting birds. From the liber of D. papyracea of the Himalaya a coarse, but very tough, paper is made. Lagetta lintearia is the Jamaica Lacebark tree, the liber of which may be separated into many FIG. 135. Vertical section of flower of Spurge Laurel. FIG. 136.-Vertical section of fruit of same, showing a solitary suspended seed. thin layers resembling lace, by maceration. It is made up into various ornamental articles. 55. Natural Order- Euphorbiacex. The Spurge Family. DISTRIBUTION.-A very large Natural Order, widely dispersed in both hemispheres; most numerous in tropical and subtropical regions.-British genera 3, species 15. Herbs, usually with milky juice, or an evergreen shrub. 3-celled (2-celled in Mercury). Type-Perennial Mercury (Mercurialis perennis). Ovary An herbaceous perennial, with opposite simple leaves, and dioecious axillary loosely spicate flowers. 8, Stamens. 9-12 Enne-Dodecandrous. Hypogynous. N.B.-In the pistillate flowers there are two filaments, but no anthers. Most of the British species of the Order belong to a distinct type, the genus Spurge (Euphorbia), characterised by achlamydeous, monoecious flowers. The staminate flowers are monandrous, and the ovary of the pistillate flower consists of 3 carpels. One pistillate and several staminate flowers are collected within a small involucre, bordered by marginal "glands," which may be mistaken by beginners for petals or calyx-lobes. A joint some distance below the anther of each staminate flower indicates the point where the filament joins the pedicel. At this node, in an allied genus, a partial perianth is developed. FIG. 141-Involucre of Spurge, bordered by four horned "glands," and containing numerous male flowers and one female. The pedicel of the latter is curved over the side of the involucre. OBSERVE the milky juice of the Spurges (Euphorbia), which is dangerously poisonous in some species, and is used by barbarous African tribes to poison their weapons. The milk of a species of Hevea, Brazilian trees, yields the best Caoutchouc exported from Para. It flows from wounds in the bark, and is allowed to dry over moulds of clay, the clay being washed out when the "India-rubber" is sufficiently stiffened. Upwards of 158,000 cwts. of Caoutchouc were imported into the United Kingdom in 1877. It must be borne in mind, however, that this product is afforded by several other plants besides Siphonia: especially by a species of Fig (Ficus) in India. Gutta-percha is the similar product of an Indian tree belonging to an Order (Sapotaceae) not represented in FIG. 142-Pistillate flower of FIG. 143.-Staminate flower Britain. Upwards of 26,000 cwts. of Gutta-percha were imported in 1877. Cassava, or Mandiocca Meal, an important article of food in the Tropics, especially of South America, is afforded by species of Manihot. The juice of one of the Cassava-producing species (M. utilissima) is a virulent poison: this is removed from the root by washing, after it has been grated. Tapioca is the fine starch which settles down from the water used to wash Cassava. It is granulated upon hot plates. The roots of the Bitter Cassava weigh from 30 lbs. to 40 lbs., and the crop is |