Ulmus parvifolia Seeds | Chinese Elm
LATIN NAME: Ulmus parvifolia
COMMON NAME: Chinese Elm
Plant Profile
The bark begins smooth and grey and then peels in irregular flakes, exposing patches of pale grey, rust-orange and olive until the trunk looks like a mosaic. This exfoliation arrives once the tree is roughly arm-thick and is the reason the species is called lacebark in the nursery trade. The leaves are small, elliptic and glossy, with a serrated edge and an asymmetric base, and they hold green later than most elms before turning a soft yellow-brown.
The fruit is a small, flat, single-seeded samara with a notch at the tip and the seed lying close to the wing base. Unlike many tree seeds these carry no real dormancy and they do not keep: a samara that has dried on a shelf for a season is often dead, which is why the species is grown from fresh fruit or, more usually, from cuttings. Each samara holds one seed only, so a given weight of fruit yields far fewer plants than the same weight of a capsule crop.
Put a shoot of this species beside common field elm and the difference shows in three places: the small, even, glossy leaf, the autumn flowering, and the samara with its seed set low in the wing and no fringe of hairs on the margin. The old sectional name Microptelea groups it with the cedar elm of Texas and Mexico, both autumn-flowering trees of warm, dry country.
No other tree has introduced as many people to bonsai. Chinese elm is cheap to raise, tolerant of being bare-rooted, and willing to throw new shoots from old wood after a hard prune; the small leaves reduce well when a tree is partly defoliated in midsummer, and the flaking bark gives a trunk an age a young plant has not earned. It is also the subject most often kept on a windowsill, which it survives better than almost any other deciduous tree, although it still grows best outdoors.
Science & Biotechnology
Dutch elm disease, caused by the fungus Ophiostoma novo-ulmi and spread by elm bark beetles of the genus Scolytus, removed most of the European and American elm canopy in the twentieth century. Ulmus parvifolia came through that era largely undamaged. It is not immune — the fungus can be isolated from it — but beetle feeding and colonisation are markedly lower on its bark, and the species has therefore been used as a parent in public elm-breeding programmes looking for durable resistance.
Uses & Benefits
Almost every elm in Europe and North America flowers on bare wood in early spring, before the leaves are out; this one breaks the rule and flowers in late summer or early autumn among fully expanded leaves, with the winged fruit ripening into autumn and often hanging on into winter. The shift matters to anyone who plants elms: flowering so late puts the tree out of step with the spring bark beetles that carry Dutch elm disease, and it gives the species a far longer season of ornamental interest than the spring-flowering elms can offer.
In the landscape trade the tree is planted as a street and median subject for its tolerance of compacted soil, drought, heat, wind and de-icing salt, and it is one of the few elms usable where ground has been filled and graded. It transplants readily from containers, even at a large size, and takes pruning into a single-stemmed avenue tree or a multi-stemmed garden specimen. In the north of its hardiness range expect some twig dieback in a severe winter; the tree regrows without help.
Growing from Seed
Elms also pass infection underground: where two trees have grafted roots in a hedge or a line of street plantings, the fungus can travel from one to the next without an insect. That is why removal of infected elms is done before the beetle flight, why neighbouring plantings are inspected, and why species with less bark-beetle appeal are so valuable in avenues. Breeding work in the United States released hybrids between this species and smooth-leaved elm under names such as ‘Frontier’, aimed at combining the lacebark’s resistance with a fastigiate street habit.
Sow the samaras as soon as they are brown and papery, pressing them onto the surface of a mix of two parts sieved loam, one part coarse sand and one part leaf mould, then covering with a bare millimetre of grit. Water from below, keep the pan outdoors or in a cool frame, and protect it from mice and birds. Seedlings lift easily and can be pricked out once the second pair of true leaves has opened. Where a particular habit is wanted, take softwood cuttings in early summer or root hardwood cuttings in a cold frame.
Water deeply and then let the top centimetre dry; elms growing fast in a pot want more water, not more fertiliser, and a balanced feed once in spring and once in early summer is ample. Prune in late winter to build the frame and again lightly after midsummer, keeping the cut surfaces small. Aphids are the standard complaint, followed by elm leaf beetles and, on stressed trees, scale; a strong jet of water and a hard prune settle the soft-bodied ones.
Our Take
This is the elm I recommend to anyone who has killed a first tree. To work in the same family at bonsai scale, Japanese zelkova is the classic Japanese counterpart, Chinese zelkova shows the same vase-shaped frame with coarser leaves, and slippery elm is the one to grow if you want the mucilaginous inner bark as well as the tree. Siberian elm is the tough northern relative for a windbreak. Sow the samaras fresh, prune hard, and the mottled trunk will come with age.
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