2. Puniceæ, Pomegranate Group. Only 2 species (Punica granatum; from Persia, Afghanistan), differing in several respects from the typical form of the Myrtaceæ. The leaves are generally opposite, without glands and marginal veins. The receptacle, calyx and corolla are red; the latter 5–8–(generally 6-) merous. Calyx valvate and corolla folded as in Lythraceæ, stamens also and epicalyx as in this order. The most characteristic feature is the inferior, spherical berry, with dry pericarp, formed from two whorls of carpels in two tiers (Fig. [525]); the interior whorl, which is also the lower, has 3 carpels, and the placentæ are situated in the inner angles of the 3 loculi; the external whorl is 5-merous, and the placentæ have originally the same position in the inner angles of the loculi, but their position is changed to the outer side of the loculi owing to the growth of the wall of the ovary, which takes place early, causing the carpels to become, as it were, turned inside out, so that the part which was turned downwards is turned upwards, and the part which was turned inwards becomes turned outwards (as in Mesembrianthemum). The edible part of the fruit is the fleshy testa, as in Ribes. The cotyledons are rolled together spirally.
Figs. 523, 524.—Eugenia caryophyllata.
Fig. 523.—Flowers (nat. size).
Fig. 524.—A bud (“clove”), long. sec. (mag.).
Fig. 525.—Punica granatum. Flower, long. sec. (nat. size).
3. Lecythideæ. The majority are South American. The leaves are scattered, without pellucid glands, and frequently dentate. The flowers are zygomorphic. The woody fruits are either indehiscent, or open by a lid. To this belong: Bertholletia (B. excelsa), the seeds well known as “Brazil-nuts,” Lecythis (Sapucaia-nuts from L. ollaria), Barringtonia.
4. Leptospermeæ. Almost entirely from Australia and the East Asian and Pacific Islands. The fruit is a capsule. The leaves are scattered, and in some placed edgewise by the twisting of the leaf-stalks.—Eucalyptus, the Australian Gum-tree; the calyx falls off like a lid (Figs. [526], [527]). Some of the species attain gigantic heights, E. amygdalina 140–150 m. with a diameter of 8 m. The leaves in E. globulus are opposite and dorsiventral on the young plant; on the older scattered, placed edgewise by the twisting of the leaf-stalk, and isolateral; Metrosideros, Calothamnus (stamens distinctly polyadelphous), Melaleuca, Leptospermum, Callistemon (the flowers are borne in spikes whose axis continues to grow after flowering, thus several zones of fruits may be seen on the same branch).
Figs. 526, 527.—Eucalyptus globulus.