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genus is considered by many authorities to be merely a section of Cupressus or of Thuya. The foliage and cones, however, are remarkably distinct, and justify its retention as a separate genus.

Evergreen trees, belonging to the tribe Cupressineæ of the order Coniferæ, with reddish bark scaling off in longitudinal shreds. Branches in false whorls or scattered, giving off secondary branches, which terminate in very flattened branch-systems, disposed in horizontal planes. These resemble in their general arrangement those of Thuya and Chamæcyparis, and are mostly tripinnate, all the axes being covered with small coriaceous leaves, adnate in part of their length, and arranged in four ranks in decussate pairs. The leaves on the main and ultimate axes differ only in size.

The ventral and dorsal leaves are flattened and ovate or spathulate, with rounded apices; the lateral leaves are carinate, more or less spreading, with a slightly acute apex, which is bent inwards. The dorsal flat leaves are shining green, and marked with a central ridge, which is often hollowed in the middle line. The ventral flat leaves have a central green ridge, with a concavity white with stomata on each side. The lateral leaves, green on the dorsal side, exhibit a single stomatic concavity on their ventral side.

Flowers monœcious, solitary, and terminal, the male and female flowers borne on separate lateral branchlets as in Thuya. Male flowers cylindric, ¼ inch long, with six decussate pairs of stamens. Female flowers with five ovules on each scale. Cones globular, almost erect, with eight clavate, woody scales, in decussate pairs from a central axis, the upper pair abortive. Seeds three to five on a scale, laterally winged, the wing not notched at the summit.

The seedling resembles that of Thuya plicata, but has broader and very blunt cotyledons, with shorter and broader primary leaves.

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