TSUGA
- Tsuga, Carrière, Traité Conif. 185 (1855); Bentham et Hooker, Gen. Pl. iii. 440 (1880); Masters, Journ. Linn. Soc. (Bot.) xxx. 28 (1893).
- Hesperopeuce, Lemmon, Rep. Calif. State Board Forestry, iii. 111 (1890).
Evergreen trees belonging to the natural order Coniferæ. Branches horizontal or pendulous, pinnately and irregularly ramified. Buds, one terminal and a few lateral, arising irregularly in the axils of some of the leaves of the current year's shoot, most of the leaves being without buds in their axils. Leaves linear, arising from the branchlets in spiral order, and usually thrown by a twisting of their petioles into a pectinate arrangement, or in one species spreading radially. Petioles short, arising from prominent leaf-bases on the branchlets, appressed against the twigs, a sharp angle being formed by the leaf with the stalk at the point of junction. The leaf has one resin-canal, lying in the middle line between the vascular bundle and the epidermis of the lower surface. The leaves persist for several years; and all the species have in consequence of this and their numerous and fine branchlets very dense foliage.
Flowers monœcious. Male flowers in the axils of the leaves of the previous years shoot near its apex, composed of numerous spirally arranged, short-stalked, two-celled anthers, with glandular-tipped connectives. Female flowers terminal on lateral shoots of the previous year, short-stalked or sub-sessile, erect, composed of spirally arranged, nearly circular scales, and membranous, usually shorter bracts. Ovules, two on each scale. Cones solitary, small, composed of concave woody imbricated scales, which persist on the axis of the cone after the escape of the seeds, and of inconspicuous bracts, which, except in one species, are concealed between the scales. The cones, ripening in one season, allow the seeds to fall out in the first autumn or winter, but remain on the tree until the summer or autumn of the second year. The seeds, two on each scale, are minute, furnished with resin vesicles and winged. The seedling has three to six cotyledons, which bear stomata on their upper surface.
Tsuga is confined to temperate North America, Japan, China, and the Himalayas. The genus consists of nine species, and is divided into two sections:—
I. Hesperopeuce, Engelmann, in Brewer and Watson, Bot. California, i. 121 (1880).
Leaves rounded or keeled above, bearing stomata on both surfaces, and radially arranged; the shorter and lateral branchlets standing in a plane at right angles
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