Order XXVIII. MYRTACEÆ.
Trees or shrubs, sometimes climbing. Leaves opposite, more rarely alternate or whorled, simple and entire, usually dotted with pellucid oil-glands and with a vein running parallel to the margin. Stipules generally absent. Flowers regular, usually hermaphrodite, solitary and axillary, or in axillary or terminal cymes panicles or racemes. Calyx-tube adnate to the ovary up to the insertion of the stamens, limb 4–5 or many-cleft or -partite, persistent or deciduous, imbricate or valvate, sometimes entire or closed in bud. Petals as many as the calyx-lobes, rarely wanting, inserted on a disc lining the calyx-tube. Stamens usually numerous, inserted on the disc with the petals; filaments free or connate at the base or united into separate bundles; anthers small, roundish. Ovary inferior or semi-inferior, crowned by a fleshy disc, sometimes 1-celled with 1 or few ovules, more often 2- to many-celled with numerous ovules; style simple; stigma capitate. Fruit either crowned by the persistent calyx-limb or marked by its scar when deciduous, usually a capsule loculicidally dehiscing into as many valves as cells, or a 1- to many-seeded berry, more rarely dry and indehiscent. Seeds angular or compressed or cylindrical; albumen usually wanting.
A very large and distinct order, readily recognised by the opposite exstipulate entire leaves, furnished with a marginal vein, and filled with transparent oil-glands. The species are mainly tropical or subtropical; most abundant in South America and Australia, much less common in Asia and Africa; more frequent in the south temperate zone than in the north, where they are decidedly rare. Genera about 80; species probably not exceeding 1800. The order includes many plants of economic importance. Some produce valuable spices, as cloves, allspice; or edible fruits, as the guava, the rose-apple, brazil-nuts, &c.; others yield aromatic essential oils, as eucalyptus, cajeput, &c. The bark of most of the species is more or less astringent. Some of the species of Eucalyptus attain a height of over 400 ft., being probably the tallest trees in the world. Of the four New Zealand genera, Leptospermum extends through Australia as far as the Malay Archipelago; Metrosideros occurs in the Pacific and Malayan Islands, Australia, and South Africa; Eugenia is mainly tropical; and Myrtus mostly American.
| * Fruit capsular. | |
| Leaves small, alternate. Flowers solitary or fascicled | 1. Leptospermum. |
| Leaves larger, opposite. Flowers usually handsome, cymose | 2. Metrosideros. |
| ** Fruit a berry. | |
| Flowers usually solitary. Embryo curved, with a long radicle | 3. Myrtus. |
| Flowers cymose. Embryo thick and fleshy, radicle short | 4. Eugenia. |
