Euphorbiaceæ

Key characteristics

Trees, shrubs, and herbaceous plants, with round or irregularly angled stems, often abounding in an acrid milky juice. The leaves are alternate, rarely opposite, simple, seldom compound, sometimes having stipules, often wanting in the succulent species. The flowers grow on terminal stalks or from the base of the leaf-stalks, variously arranged, sometimes surrounded by an involucre resembling a calyx. The calyx is below the ovary and has various scales and glands, the petals when developed alternate with its lobes. The stamens and pistil are in separate flowers, the filaments free or united, the anthers two-celled gaping longitudinally. The ovary is formed of three carpels connected by a central axis, either stalked or not. The styles are equal in number to the carpels; the stigmas are single and distinct, or lobed; the fruit consists of three dry capsules, splitting and separating from the axis with elasticity. The cells are one or two-seeded: the seeds contain fleshy oily albumen.

The separation of stamens and pistil, and want of petals connect this Tribe with Artocarpaceæ and Urticaceæ. Those which have petals and united stamens and carpels form a link with the Mallow Tribe.

A poisonous milky secretion, and stinging hairs, belong generally to these plants.

Select plants in this order

Not all plants listed are illustrated and not all plants illustrated are listed.

• Euphorbia records the name of a renowned physician of King Juba in Barbary, supposed to have been the first to discovery the medicinal properties of the genus. It displays a marvellous variety of form in its species.
• Some are small herbs, as E. Peplus (1), one of the commonest weeds in cultivated ground, of no value except that the acrid milk cures warts.
• Other shrubs, E. canariensis, twenty feet in height.
• Some are of a succulent nature, and when leafless and spiny assume the aspect of Cactus.
• E. meloformis has a melon-shaped stem, from which the flowers proceed on the top, after the manner of Cactus; and the great Medusa-head Euphorbia of Africa has a strong resemblance to that Tribe also. But an obvious distinction exists in the spines, which in these plants are either single or in pairs, never clusters as in Cactus.
• E. splendens (2) is an example of a coloured involucre having the appearance of petals, and is one of the most brilliant of the genus. Some of the East Indian species have bright yellow involucres.
• Although a virulent poison pervades the tribe, yet a considerable quantity of wholesome food is obtained from it by skilful preparation with heat. The principal plant yielding the supply is Manihot utilissima, from the long roots of which, weighing thirty pounds, the natives of S. America make Cassava for their own use, and Tapioca for exportation. Cassava-bread is the chief nourishment of the Indians of Brazil and Guiana, but is not thought wholesome by the Europeans.
• Euphorbia balsamifera is boiled into a jelly by the inhabitants of the Canaries, who consider it a delicacy. The oil of the seeds is the most important medicinal product, and is of a very powerful nature: that of Croton Tiglium, an East Indian tree, and of Ricinus communis, the Castor-oil plant of Africa, are of extensive value. The latter is known here only as herbaceous, in its native country it is arborescent; the spiny capsules full of oily seeds are a very ancient medicine.
• Euphorbia officinarum, and others, afford the medicinal gum resin Euphorbium.
• The juice of E. linearis is a remedy for week eyes in Brazil.
• Fifteen species of Spurge are natives of Britain, thirty-three grow on the Continent. It appears to be one of those plants which, if found at all, is abundant. The steep hills in the interior of South Africa are thickly clothed with low bushes, over which countless tall Euphorbias rise. Several are seen in the sandy lands of Nubia.
• The juice of E. phosphorica sheds a light during hot nights.
• Jatropha (3) is a genus of some beauty in the West Indies and South America.
• Poinsettia (4) in its native country bears a cluster of red bracts twenty inches across, clearly showing a transition state between leaves and petals; these constitute the ornament of the plant, for the flowers are small, and, though curious in structure, not beautiful.
• The Sand-box tree of the West Indies, crepitans (8),^* is chiefly known here in its curious seed-vessel, which bursts with a loud noise when ripe.
• The fruits of Anda, Emblica, and a few more, are eatable in their respective countries.
• The juice of Crozophora, Ditassa, and others, yields useful dyes in Brazil.
• Siphonia elastica affords, from its milky juice, the bottle India-rubber, retaining the pale colour within, but blackened by smoke without.
• Hippomane Mancinella contains in its pure white liquid one of the most fatal of poisons.
• The Tallow-tree of China, Stillingia sebifera, yields an oily substance around the seeds which serves for candles.
• Elæococca oil is used for lamps and for painting.
• Cascarilla bark is obtained chiefly from Eleuthera in the Bahamas.
• Among the useful plants of this tribe is Buxus sempervirens, the Box-tree, the wood of which is excellent for engraving; it grows remarkably well on Box Hill, in Surrey, and when the trees were cut in 1815, the value was 10,000l. On the Pyrenees considerable tracts are covered with this beautiful evergreen shrub. The bitter leaves are unwholesome to camels if eaten by them Persia, where the trees abound.

Locations

This extensive tribe, containing as many as 2500 species, exists most abundantly in the Tropics of America, diminishing from the Equator: very few are known in N. America, as far as Canada. In North and South Africa are many succulent species.

Legend