Glyptostrobus pensilis

Scientific name: Glyptostrobus pensilis  (Staunton ex D.Don) K. Koch  1873

Synonyms: Cuprespinnata heterophylla (Brongn.) J. Nelson, Cuprespinnata sinensis (J. Forbes) J. Nelson, Cupressepinnata heterophylla (Brongn.) J.Nelson, Cupressepinnata sinensis (J.Forbes) J.Nelson, Cupressus nucifera Carrière, Glyptostrobus aquaticus (Roxb.) R.Parker, Glyptostrobus heterophyllus (Brongn.) Endl., Glyptostrobus sinensis A.Henry ex Loder, Juniperus aquatica Roxb., Sabina aquatica (Roxb.) Antoine, Schubertia nucifera Denham ex Endl., Taxodium heterophyllum Brongn., Taxodium japonicum Dehnh. ex Gordon, Taxodium sinense J.Forbes, Thuja lavandulifolia Poir., Thuja pensilis Abel, Thuja pensilis Staunton ex D.Don

Common names: Chinese swamp cypress, Chinese water fir, Water pine (English), Shui song (Chinese)

Description

Tree to 25 m tall, with trunk to 1.2 m in diameter, only slightly flaring at the base. Roots bearing low, rounded aerial outgrowths (“knees”) when growing by or in water. Bark light reddish brown, weathering very pale tan or gray, shallowly ridged and furrowed. Crown rather irregular, even in youth, sparse and open, with numerous but thin and airy tufts of branchlets at the tips of the thin branches. Branchlets completely hidden by the attached bases of elongate leaves or by the overlapping blades of scale leaves. Needle- and clawlike leaves 9-20 mm long, scale leaves 2-3 mm long, those of long shoots persisting 2-3 years. Pollen cones about 4 mm long. Seed cones 1.5-2.5 cm long, 1.3-1.5 cm across. Seeds about 0.7 mm long with the wing extending about the same length beyond the base.

Primarily in southern China (from southeastern Yunnan to Fujian, most abundant in coastal lowlands of Fujian and Guangdong provinces) with a few localities in Vietnam. Swamp and other wet places, such as margins of rice paddies; 0-700(-1,000) m.

Conservation Status

Red List Category & Criteria: Critically Endangered

Glyptostrobus pensilis was formerly very widespread in China, Vietnam and possibly Laos. In China and Vietnam most of the natural plants have been killed due to expanding agriculture. It appears that there are no plants remaining in the wild in China and that the only remaining natural subpopulations are in Vietnam and Laos. Although the total number of trees is more than 250, very few, if any are producing viable seed and the majority of trees in Vietnam are in decline. The species is therefore listed as Critically Endangered under criterion C. It could possibly also meet this under criterion A, but it is not known over what time period the greatest population reduction took place (it could well have been a long slow process exceeding three generations). Given current trends this species could well become Critically Endangered (Possibly Extinct in the Wild) in the near future.

A heliophilous species, intolerant of competition and usually growing in pure stands or solitary along streams. In China it is mainly found on river floodplains and in deltas, always near or in water, where it develops a buttressed base and occasionally pneumatophores; also extensively planted along rivers and canals. In Vietnam and Laos it occurs along streams and in seasonally inundated areas at altitudes between 500 and 700 m asl.

In China and Vietnam habitat loss due to intensive agriculture has been the main cause of decline. The subpopulations in Vietnam are within coffee plantations, the water table has been altered and the trees are no longer producing fertile seed. Illegal logging of live and dead trees within the nature reserves has recently been reported. The largest of the recently discovered stands in Laos were located within the inundation zone of the newly completed Nam Theun II hydro scheme and have been flooded. Several small stands are located outside of this zone on land that has been allocated to villages for forestry or agriculture, and each stand has been impacted to various degrees by logging, construction of fish ponds, and clearing for food crops.

The rather soft, yellowish wood is like most cupressaceous wood decay resistant and finds uses in China ranging from furniture to building of bridges. The wood of the roots is very light and due to its buoyancy it is used in China to make life-saving rings. This species is widely cultivated in southern China and planted along rivers and canals as well as in parks; except for the latter localities mostly to harvest the timber followed by replanting. In Vietnam wood is highly valued for crafts and is reputed to have anti-cancer properties although there is no scientific evidence to support this.

Surveys are required of all potential areas of suitable habitat in China to see if any wild plants still remain. The subpopulations in southern Vietnam and Laos should receive urgent site protection and restoration efforts are required to increase the size and viability of these subpopulations. If that is not done this species could well become Critically Endangered (Possibly Extinct in the Wild).

References

• Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
• Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
• IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.