The Tea tree (_Thea viridis_) is very nearly allied to the Camellia; but there are many points of difference. The flower of the Tea tree has a footstalk; the calyx has only five sepals; the filaments of the stamens do not grow together; the capsules are three-seeded; and the dissepiments are formed by the edges of the valves being bent inwards, instead of being attached to a central axis. The leaves are also much longer than they are broad, and they are of a thinner texture and pale green; and the outside of the capsule, which is furrowed in the Camellia, is quite smooth in the Tea tree. It is said that both the green and the black Tea are made from the leaves of _Thea viridis_; but there is another species called _Thea Bohea_, which has smaller leaves, and is a more tender, and less vigorous-growing plant. The young leaves of _Camellia Sasanqua_, and some of the other Camellias, are also dried, and mixed with the tea. All these plants are natives of Japan and China, and require a slight protection in England during winter. ORDER XXXVI.—OLACINEÆ.—THE OLAX TRIBE. Exotic trees from the East and West Indies, little known in Britain. _Heistria coccinea_, a native of Martinique, is said to be the Partridge wood of the cabinet-makers. ORDER XXXVII.—AURANTIACEÆ.—THE ORANGE TRIBE. [Illustration: FIG. 121.—FLOWER AND SEED OF THE ORANGE.] The natural order Aurantiaceæ contains fourteen genera; but the only one I think my readers will feel an interest in is the genus Citrus. This genus comprises, among several other species, _C. medica_, the Citron; _C. Limetta_, the sweet Lime; _C. Limonum_, the Lemon; _C. Paradisi_, the Forbidden fruit; _C. decumana_, the Shaddock; _C. Aurantium_, the Sweet Orange; and _C. vulgaris_, the Bitter or Seville Orange. to these may be added _C. nobilis_ the Mandarin Orange, the fruit of which is reddish, and which parts naturally from its rind, which is sweet, and may be eaten. All the species agree in having a tube-like calyx, scalloped into five short teeth, and a flower of generally five fleshy petals, (see _a_ in _fig._ 121), though the number occasionally varies from four to nine. These petals are elliptic in shape, concave, and always widely opened. In the centre of the flower are the stamens, varying from twenty (which is the ordinary number) to sixty; the anthers are two-lobed, and oblong, and the filaments are somewhat thickened at the base, and united there into several small bundles (_b_), but free above. The pistil has a somewhat globular ovary, with a cylindrical style, terminating in a stigma, which is slightly raised in the centre. The disk in which the stamens are inserted, forms a ring round the ovary. The fruit (_fig._ 122), which is considered by botanists to be a kind of berry, is in fact a seed-vessel with numerous cells, divided by dissepiments and a central placenta (_a_); the cells being the quarters of the Orange, the dissepiments the divisions between them, and the placenta the central pith.