Culture
Winter hardy to USDA Zones 7a-11 where this tree grows best in wet soils including up to 24” of standing water. Full sun but tolerates light shade. Dry soils must be avoided.
Noteworthy Characteristics
Glyptostrobus pensilis, commonly known as Chinese swamp cypress, is a deciduous needled conifer in the bald cypress family that typically matures to 60-90’ tall featuring gray bark and a conical to columnar crown. It is native to flooded or waterlogged soils along river banks, ponds and in swamps, often growing in standing water to 24” deep in moist, subtropical to tropical areas in southeastern China (Fujian to Yunnan), northern Vietnam and northern Loa PDR (Laos). Although formerly widespread in China and Vietnam, this tree is now rare in the wild. Wild populations may in fact no longer exist in China where this tree has succumbed over time to agricultural encroachment and excessive harvest of its valuable decay-resistant wood. Trees growing in China today are cultivated ones planted by humans. Trees growing in the wild in Vietnam and Loa PDR today are limited to a few remaining populations where the trees therein are in significant decline with few if any trees bearing seeds.
This is the only species in the genus Glyptostrobus. It is currently listed on the IUCN Red List of Threatened Species as “Critically Endangered”. Extinction in the wild may occur in the near future.
Although very similar in appearance to bald cypress trees in the closely related Taxodium genus, Chinese swamp cypress primarily differs from Taxodium by having trimorphic leaves (Taxodium are dimorphic), elongated scales (Taxodium are rounded) and slightly longer cone stalks. When grown in water, both produce knee-like roots (pneumatophores) which protrude above the water helping to bring oxygen to the root system.
Leaves on outer sterile branches are flat and linear. Leaves on cone-bearing branches are lanceolate to needle-like. Monoecious insignificant flowers emerge green but mature to brown. Male cones are clusters of tassels while the small 1-inch female cones grow erect and are pear shaped. Foliage turns deep reddish-brown in fall.
Synonymous with Glyptostrobus lineatus.
Genus name comes from the Greek words glyptos meaning engraved or carved and strobilus meaning a cone in reference to the median slit in the margin of the scales or to the spirally arranged cone scales.
Specific epithet comes from the Latin word pensus meaning hanging down in reference to the pendant branchlets.
Problems
No serious insect or disease problems.
Uses
Critically endangered species. Best planted in wet places. Traditional uses have included erosion control or river bank stabilization.