红杉 hong shan [Chinese] (literally, red fir); Chinese larch. For var. himalaica, Langtang larch; 喜马拉雅红杉 Xu mi hong shan [Chinese] (Wu and Raven 1999).
Different authors have varied views on the systematics of this species. Wu and Raven (1999) identified three varieties of L. potaninii: the type, L. potaninii var. australis, and L. potaninii var. chinensis. They also regarded L. himalaica as a distinct species, whereas Cheng and Fu (1978) had reduced it to synonymy.
Eckenwalder (2009) accepted var. australis and placed chinensis into synonymy with the type, accepting these as geographically distinct taxa while noting that "much more needs to be known about variation throughout the range of the species before there can be much confidence about any division of the species into varieties."
Farjon (2010), on the other hand, working with the available herbarium material, went with a more complex taxonomy. He accepted the type and var. chinensis of Wu and Raven (1999), reduced their L. himalaica to a variety, disregarded their var. australis, and recognized var. macrocarpa Y.W. Law 1975 (which Wu and Raven had reduced to synonymy with var. australis).
Finally, Debreczy and Rácz (2011) reduced var. australis and var. macrocarpa to synonymy with the type variety, while still recognizing var. chinensis as geographically isolated and both ecologically and morphologically distinct, and maintaining L. himalaica as a good species.
Personally, I have seen this species in the field at a few locations, but otherwise am reliant upon published accounts. In this treatment I have chosen to recognize L. himalaica as a variety, while recognizing that it could equally be treated as good species that is (probably) more similar to L. potaninii than to any other taxon of Larix, the distinction between species and variety being somewhat arbitrary in the absence of better knowledge (preferably including molecular studies as well as more extensive collections) about both taxa. I also treat L. potaninii var. chinensis as a good variety, since so many prior authors have done so. That just leaves the question of var. macrocarpa or var. australis, both of which are here treated as synonymous with the type. This leads to the following synonymy:
for Larix potaninii Batalin var. potaninii:
for Larix potaninii Batalin var. chinensis (Beissn.) L. K. Fu & Nan Li 1997:
for Larix potaninii Batalin var. himalaica (W.C. Cheng & L.K. Fu) Farjon & Silba 1990:
Trees up to 50 m tall and 100 cm dbh. Bark gray or gray-brown, smooth, becoming rough and longitudinally fissured on old trees. Crown conical, branches short, horizontal. Long shoots slender, drooping, red-brown or purple-brown, glabrous or very slightly hairy, turning grey after first year. Short shoots 3-8 mm diameter, densely covered with yellow-brown hairs at apex; winter buds brown or dark brown, resinous, glossy, ovoid. Leaves 12-35 mm long, 1-1.5 mm across, prominently keeled on both sides so as to seem 4-sided, apex pointed. Seed cones cylindric to ovoid, 2.5-7.5 × 1.5-3.5 cm at maturity, red or purple when young, maturing a deep purple, changing to light gray-brown; sessile. Seed scales 35-90, slightly convex, 0.8-1.6 × 0.8-1.1 cm, apex obtuse or sometimes notched; bracts often exserted, purple-brown, oblong-lanceolate, acute or acuminate. Seeds light brown with purple spots, obliquely obovoid, about 3 mm long with a 6 mm wing. Pollination occurs April to May, and seed maturity in October (Dallimore et al. 1967, Wu and Raven 1999).
"L. potanini can be distinguished from other larches, except L. lyallii, by its 4-sided leaves, and from L. lyallii by its less hairy shoots" (Dallimore et al. 1967).
Nepal; E and S Tibet; and China: S Gansu, S Shaanxi, W Sichuan, and NW Yunnan, at elevations of 2,350 to 4,300 m, on acidic podzol soils; climate is cold, precipitation is 800 to 2,000 mm/yr. Associated trees are mainly conifers including species of Abies, Picea, Tsuga, Juniperus, Cephalotaxus and Taxus (Farjon 2010).
For the type variety, distribution and habitat is as above, except not reported in Nepal.
For var. chinensis, distribution is confined to Taibai Shan in S Shaanxi, at elevations of 2,600-3,500 m (Wu and Raven 1999).
For var. himalaica, distribution is confined to Nepal (Langtang Khola) and neighboring S Tibet, at elevations of 2,800-3,700 m; it is reported only in the vicinity of Mt. Everest, in valleys on both the north and south sides (Wang and Zhong 1995, Wu and Raven 1999, Farjon 2010). Visiting populations in Nepal, Debreczy and Racz (2011) described it as occurring in riverside ravines and on rocky outcrops adjoining dense forests of Abies spectabilis, Tsuga dumosa, Alnus, Betula, Acer and Rhododendron; or in low scrub with Juniperus indica, J. recurva, and Rhododendron.
The type variety is hardy to Zone 5 (cold hardiness limit between -28.8°C and -23.3°C), while var. himalaica is hardy to Zone 7 (cold hardiness limit between -17.7°C and -12.2°C) (Bannister and Neuner 2001).
"Wilson records it from the mountains of [Shaanxi] province westward to those of the Chino-Tibetan borderland. It is a common tree around [Kangding] at altitudes ranging from [2,290-3,350 m]. He further says, that it is a strikingly handsome tree and that it is the common larch of W. [Sichuan], where it occurs at elevations of [2,290-3,350 m] At its lower altitude it is scattered in moist woods, more especially by the sides of streams, with other conifers and broad-leaved trees, becoming more abundant as it ascends and forming forests at the higher alpine regions" (Dallimore et al. 1967).
The timber is used for construction, railroad ties, and furniture, and the bark yields tannins. The species is also used for afforestation (Wu and Raven 1999).
Easily seen along the highway W of Kangding, Sichuan (Kham). Var. himalaica is reported from Qomolungma National Park in Tibet.
The epithet recalls Russian botanist Grigorii N. Potanin (Григорий Николаевич Потанин, 1835-1920), who collected in western China in the 1880's.
Batalin, A.T. 1894. Notae de plantis asiaticis XLIX-LXXI. Trudy Imp. S.-Petersburgsk. Bot. Sada 13:385.
Cheng, W.C. and L.K. Fu 1975. P. 84 in W.C. Cheng et al., Acta Phytotaxonomica Sinica 13(4).
Debreczy, Z. and I. Rácz. 2011. Conifers Around the World. Vols. 1-2. Budapest: DendroPress Ltd.
Wang Shimin and Zhong Shenxian in Schmidt and McDonald 1995.
The species account at Threatened Conifers of the World.
Last Modified 2017-12-29