This genus was separated from Thuja on account of a rather slight difference in the form of the fruit, which is composed of about 6 scales in opposite pairs, with a hook or tubercle near the apex, and 2 wingless seeds at the base. The scales are somewhat fleshy at first, but ultimately become more or less coriaceous or woody. This genus is, so far as at present known, limited to a single species, which is, however, almost endless in its forms. The name is probably a modification of 14 Biota 397 life, signifying the same as its trivial name, Tree of Life, or Arbor Vitas.

1. B. orientalis, syn. Thuja orientalis. Chinese Arbor Vitaa. - A small compact densely-branched tree, from 15 to 20 feet high, with compressed crowded branchlets. Leaves bright green, very small, and closely imbricated, with slight depression or channel above, destitute of tubercles. The typical form of this species is a handsome shrub, preferable to the other Arbor Vitals in some respects, especially for its brighter green foliage and less powerful odour, and some of its numerous varieties may be numbered amongst the most ornamental of evergreens, requiring little space for their full development. There is scarcely any appreciable difference in the foliage of most of these forms, except that in some there is a tendency to produce linear spreading leaves. This is more particularly the case in the variety Meldensis, syn. hybrida, which has decurrent glaucous linear acute spreading leaves, and the fruits of the ordinary shape. This was raised from seed in a garden at Meaux, amongst a lot of the ordinary form, and at first supposed to be a hybrid between the Red Cedar and the Chinese Arbor Vitae, but subsequent investigation has proved it to be a variety of the latter. It is more curious than beautiful, as it rarely forms a good specimen. Another very distinct and remarkable variety is that named filiformis, syn. flageltiformis, pendula, etc. This has long pendulous flexible whip-like branchlets, and longer though appressed acute leaves. A very beautiful and desirable shrub for sheltered localities on well drained soil where alone it will flourish satisfactorily. The Grolden Cypress, B. orientalis aurea, is one of the most familiar of the compact-growing varieties, being nearly spherical in outline, with the young foliage of a bright yellow tinge. This is very pretty when the yellowness is not too highly developed, for in that case it often happens that the foliage is too delicate to withstand the effect of the direct rays of the sun. B. orientalis, var. elegantissima, is an upright somewhat loose-growing form with the young foliage prettily variegated with yellow and green. B. o. var. Sieboldii, syn. B. Japonica is a very hardy and ornamental compact conical shrub, retaining its pleasing bright verdure throughout the winter. The variety glauca is of rather irregular growth, with reddish-brown bark and dark green and glaucous foliage. It is said to be tender, but we have not observed that it has been affected by the cold. B. Tartarica is a distinct and very hardy form of dense erect habit with dark green shining foliage, and B. pyramidalis is still narrower in outline. These two are sometimes considered as slight variations of a species distinct from B. orientalis, but the intermediate gradations will not admit of that view. B. 0. pygmaea is a very dwarf slow-growing kind with glaucous foliage, and B. o. compacta is also exceedingly small in stature with very slender branchlets and bright green foliage. We might go on enumerating varieties, but the above include all that is best of the genus, and collectors will necessarily have a more complete guide than this work. We may add the following names for the purpose of showing their place. B. monstrosa, macrocarpa, gracilis, syn. B. Nepalensis, falcata and argentea. This species is a native of India, China, and Japan, and many of the most marked varieties have been imported direct from the two latter countries.