Glyptostrobus pensilis Seeds | Chinese Swamp Cypress
LATIN NAME: Glyptostrobus pensilis
COMMON NAME: Chinese Swamp Cypress
Plant Profile
Wild Chinese swamp cypress is nearly gone. The species survives mainly as trees planted generations ago along village ponds, field bunds and fishpond banks in southern China, kept for timber and shade rather than for wildlife. Several of the oldest survivors stand in temple grounds and are treated as village landmarks. That makes it one of the very few conifers whose main remaining population is a cultural landscape.
The foliage is dimorphic. Long leading shoots carry short awl-shaped leaves pressed close to the stem, while lateral shoots carry soft needle leaves in two ranks. In autumn the whole lateral shoot is shed, leaves and all, so the tree drops its foliage in sprays rather than leaf by leaf. Golden autumn colour comes first, then the branches are bare.
Taxodium distichum, the bald cypress of the southeastern United States, also grows knees and also drops its foliage in sprays, but its seed cones are nearly round. Dawn redwood, Metasequoia glyptostroboides, keeps opposite leaves and forms proper winter buds. Chinese swamp cypress holds small pear-shaped cones on long stalks, the quickest way to tell the three apart.
Glyptostrobus was once widespread across the northern hemisphere; leaves and cones turn up in Tertiary deposits in Europe, North America and Japan. Today the genus is down to one species in a small corner of southern China, a contraction that makes it a standard example in discussions of relict conifers. Most surviving trees are planted rather than wild, which complicates conservation planning.
Science & Biotechnology
The heartwood of the swamp cypresses is loaded with abietane diterpenes, among them ferruginol and sugiol, compounds that help the timber resist decay in wet ground. Relatives in the same group produce taxodione and taxodone, diterpenoids that have been studied for cytotoxic activity. Leaf and twig oils carry the usual monoterpenes, alpha-pinene and limonene among them.
Because it grows in saturated ground and moves water quickly, Chinese swamp cypress has been planted in constructed wetlands as part of wastewater treatment. Its tissues take up metals from the mud, and the trees shelter the microbial communities that do much of the actual cleaning. The same physiology suits it to stabilising pond banks and ditches.
Uses & Benefits
The wood is light and easy to work, and has been used for boxes, matches and household boards; because it stands up to water, it has also gone into paddy-field equipment. Old trees often hollow while still growing, and the timber is light enough to float, which made it easy to move by water. In a garden, plant it at the edge of a pond or in ground that stays damp, where it makes a graceful specimen with a strong autumn display.
Growing from Seed
The trunk flares at the base into a swollen buttress, and the root system pushes up woody knees that break the surface of the mud around the tree. Both are adaptations to waterlogged ground, where roots have to reach air. The knees are pneumatophores in all but name, porous wood that lets oxygen down to roots sealed in mud. The base of an old tree can be broad enough to sit on, and the knees grow tall where the water is permanent.
Sow on the surface of a mix of two parts loam, one part leaf mould and one part coarse sand, pressing the seed in and covering it with a thin layer of grit. Stand the pan in a tray of water and keep the level just below the rim, so the medium stays saturated. Keep it outdoors through winter in a shaded frame; this is a tree that never wants to dry out.
Prick the seedlings into deep pots once they are a hand high, keeping the pots standing in water through the growing season. Plant out when the trunks are as thick as a finger, setting them where the roots can reach permanent moisture and spacing pond-side plantings several metres apart. Mulch heavily, feed lightly in spring, and cut out competing stems while the trunk is forming. In a cold garden, shelter young plants from drying wind through their first winter and never let the roots freeze dry.
Our Take
Wet-ground conifers are a small and interesting club. Taxodium distichum is the American bald cypress and the closest lookalike, while Metasequoia glyptostroboides gives the same feathery autumn gold on drier ground. For a broadleaved companion at the water’s edge, Nyssa sinensis works well and is listed as Nyssa sinensis. All three can be started in the same wet pan.
Related Reading
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