Tsangpo Cypress

An endangered species. Perhaps better treated as a variety of Cupressus torulosa, from which it differs mainly in its thicker ultimate branchlets, which are not drooping but spreading (xeromorphy), and in that some stands in SE Xizang contain very massive trees. However, some herbarium specimens of C. torulosa collected outside China in the W Himalayan region have similarly thick foliage, while another specimen from SE Xizang has ultimate branchlets only 0.8 mm wide.

Trees to 45 m tall; trunk 3(-6) m d.b.h.; branchlets densely arranged, often glaucous, stout, usually 4-angled, rarely terete, ultimate ones not drooping, 1.5-2 mm in diam. Leaves closely arranged, in 4 ranks, glaucous, scalelike, obtusely ridged or arched (gibbous) and with a rounded central abaxial gland. Seed cones usually glaucous, oblong-globose, 1.5-2 × 1.3-1.6 cm; cone scales circa 12, each fertile scale with numerous seeds; bracts with a prominent, large, free mucro at apex. 2n = 22*

SE Xizang.

* Mountain slopes, along rivers; 3000-3400 m.

Cupressus gigantea is close relative of Cupressus chengiana, but differs from the latter in its glaucous (vs. not glaucous) branchlets, bracts with a prominent, large, free mucro at apex (vs. a small, free mucro at apex).

Cupressus gigantea is occurring in SE Xizang.

Recent phylogenetic investigations of Cupressoideae have found evidence to suggest that Cupressus is not monophyletic. The Cupressus was divided into an Old World clade and a New World clade. Data from anatomy, biochemistry, micromorphology, reproductive development, reproductive morphology, and vegetative morphology were combined with molecular sequence data (matK, NEEDLY intron 2, nrITS, rbcL, and trnL) to produce the most complete hypothesis of evolutionary relationships within Cupressoideae. Callitropsis, Cupressus, and Juniperus formed a well-supported monophyletic group (100%). Within this clade, the only demonstrably monophyletic genus was Juniperus (100%). Monophyly of the Old World species of Cupressus was well supported (100%). Old World species of Cupressus were sister to Juniperus (99%). Callitropsis and the New World species of Cupressus were resolved as the sister group to the Old World Cupressus plus Juniperus clade (100%) (Little, 2006).

Trees to 45 m tall; trunk 3 (-6) m d.b.h.; branchlets densely arranged, often glaucous, stout, usually 4-angled, rarely terete, ultimate ones not drooping, 1.5-2 mm in diameter. Leaves closely arranged, in 4 ranks, glaucous, scalelike, obtusely ridged or arched (gibbous) and with a rounded central abaxial gland. Seed cones usually glaucous, oblong-globose, 1.5-2 cm long, 1.3-1.6 cm wide; cone scales circa 12, each fertile scale with numerous seeds; bracts with a prominent, large, free mucro at apex.

The chromosomal number of Cupressus gigantea is 2n = 22 (Liang, 1990).

Growing in mountain slopes, along rivers; 3000-3400 m.

Cupressus gigantea is reported be vulnerable (Conifer Specialist Group, 1998).

Cupressus gigantea, the Tibetan cypress, is a species of conifer in the family Cupressaceae in Asia. C. gigantea was previously classified as a subspecies of Cupressus torulosa because of their similar morphological characteristics and close distribution, but have since been genetically distinguished as separate species.