|Ulmus subsp. var.||Elm|
Elm leaves are alternate, with simple, single- or, most commonly, doubly-serrate margins, usually asymmetric at the base and acuminate at the apex. The genus is hermaphroditic, having perfect flowers which, being wind-pollinated, are apetalous. The fruit is a round wind-dispersed samara. All species are tolerant of a wide range of soils and pH levels but, with few exceptions, demand good drainage.
|Standard Cyclopedia of Horticulture|
Ulmus (ancient Latin name of the elm). Ulmaceae. Elm. Ornamental trees chiefly grown for their handsome foliage and often planted as shade and street trees.
Deciduous, rarely half-evergreen: winter buds conspicuous, with imbricate scales: lvs. short-petioled, usually unequal at the base, with caducous stipules: fls. perfect or rarely polygamous, apetalous, in axillary clusters or racemes; calyx campanulate, 4-9-lobed, with an equal number of stamens; ovary superior, with a 2-lobed style, usually 1-loculed and with 1 ovule: fr. a slightly compressed dry nutlet, with a broad rarely narrow membranous wing all around (Fig. 3877).— About 18 species of Ulmus are known, distributed through the colder and temperate regions of the northern hemisphere, in N. Amer. south to S. Mex., but none west of the Rocky Mts., and in Asia south to the Himalayas. The wood is heavy, hard, and tough and often difficult to split. It is especially useful in the manufacture of wagon-wheels, agricultural implements, and for boat-building. The inner mucilaginous bark of the branches of U. fulva is used medicinally and that of some Chinese species is made into meal and used for food. The tough inner bark of some species furnishes a kind of bass which is sometimes woven into a coarse cloth, especially that of U. japonica in Japan.
The elms are mostly tall trees, rarely shrubby, with alternate usually 2-ranked, medium-sized or sometimes rather small leaves and with inconspicuous generally greenish brown flowers appearing mostly before the leaves. Most of the cultivated species are hardy North, but U. crassifolia and U. alata are tender; U. parvifolia and U. serotina are of doubtful hardiness, although they have persisted near Boston. The elms are mostly tall and long-lived and are very valuable for park planting and for avenue trees, especially U. americana, which is the favorite tree for street planting and as a shade tree for dwelling houses in the northeastern states. It is the most characteristic tree of this region and of characteristic beauty. Its habit is at once majestic and graceful, and the wide-spreading head, borne usually at a considerable height on a straight and shapely trunk, affords ample shade and shelter. Besides the American elm several other species are used as avenue trees, as Ulmus fulva, U. racemosa, and the European U. campestris, U. hollandica, and U. foliacea. Of U. hollandica, the vars. belgica, superba, Klemmer are among the best for street planting; of U. foliacea, the vars. stricta, Wheatleyi, and Dampieri. In the southern states U. serotina, U. crassifolia, and U. alata, are sometimes used as avenue trees. There are several varieties of striking and peculiar habit, as U. glabra var. fastigiata and U. foliacea var. monumentalis, with narrow columnar head; U. glabra var. pendula, with horizontal limbs forming wide-spreading tiers; U. glabra var. Camperdownii with long pendulous branches. U. foliacea var. umbraculifera, with a dense, globose and rather small head, may be used as an avenue tree for formal gardens. Several species and varieties are interesting in winter on account of their branches being furnished with broad corky wings. The foliage of most species turns pale yellow in fall, but that of the European species remains green much longer.
Unfortunately many insects and fungi prey upon the elm, especially on the American elm. One of the most destructive is the elm leaf-beetle, which destroys the foliage. The canker-worm is also serious; to keep it from doing damage, band the trunks a few feet above the ground with cloth covered with a sticky substance, which prevents the ascent of the wingless female. The trees should be sprayed. A borer, Saperda tridentata, sometimes does considerable damage to the wood. The elms grow best in rich and rather moist soil, and the American elm especially requires such a soil to attain its full beauty, but some species, as U. racemosa and U. alata, do well in drier situations. Elm trees are not difficult to transplant, and rather large trees may be moved successfully if the work is done carefully. They bear pruning well, but generally do not need much attention of this kind. Propagation is by seeds ripening usually in May or June and sown at once. Most of the seeds will germinate after a few days, but some remain dormant until the following spring. Increased also by layers, which are usually put down in autumn and are fit to be removed in one year. A moist and rather light soil is best for this method. Trees raised from layers are said to bear seed less early and less profusely and are therefore especially recommended for street trees, as the foliage of trees that fruit slightly or not at all is larger and more abundant. Dwarf forms of U. foliacea and also U. parvifolia and U. pumila may be raised from greenwood cuttings under glass, the cuttings growing most readily if taken from forced plants. U. campestris, U. foliacea, and some of their varieties are also propagated by suckers. In nurseries most of the varieties are propagated by grafting, either by budding in summer or by whip- or splice- grafting in spring outdoors or on potted stock in the greenhouse. U. americana, U. campestris, U. foliacea, and U. glabra are used for stocks.
U. arbuscula, Wolf (U. glabra x U. pumila). Shrubby tree: lvs. elliptic to elliptic-oblong, doubly serrate, nearly equal at the base, 3/4 - 3 in. long, on shoots to 6 in. long. Originated in St. Petersburg. — U. Bergmanniana, Schneid. Allied to U. glabra. Tree, to 50 ft.: branchlets glabrous: lvs. obovate-oblong to elliptic, acuminate, doubly serrate, glabrous, 2 1/2 - 5 in. long; petioles very short: fr. roundish-obovate, glabrous, 1/2 – 3/4 in. long. Cent. China. Var. lasiophylla, Schneid. Lvs. pubescent beneath. W. China. — U. Davidiana, Planch. Allied to U. japonica. Medium-sized tree: young branchlets glabrous, later pale grayish brown or pale brown: lvs. short-petioled, obovate or elliptic ovate, doubly serrate, slightly pubescent beneath, 2-4 1/2 in. long: fr. pubescent in the middle, but glabrous toward the margin. N. China. — U. elliptica, Koch. Allied to U. glabra. Branchlets pubescent: lvs. elliptic to elliptic-oblong, glabrous and nearly smooth above, slightly pubescent beneath, 3 1/2-6 in. long: fr. obovate, with the seed in the pubescent middle. Transcaucasia, Armenia. The plant cult. under this name is U. fulva. — U. Keakii, Sieb.-Zelkova serrata. — U. macrocarpa, Hance. Small tree or shrub: young branchlets pubescent, later pale brown, often with 2 corky wings: lvs. ovate, coarsely doubly serrate, rough above, slightly pubescent or nearly glabrous below, 1 1/2 - 3 in. long: fr. obovate, with the nutlet in the middle, pubescent and ciliate, about 1 in. long. N. China. Possibly U. rotundifolia, Carr. (R.H. 1868, p. 374), belongs here. — U. minor, Mill. (U. surculosa var. argutifolia, Stokes. U. sativa, Moss, not Mill. U. Plotii, Druce). Allied to U. foliacea. Suckering tree, to 90 ft., with ascending branches and pendulous branchlets: lvs. obovate or elliptic, dull and slightly scabrous above, pubescent beneath at first, 1 1/2 – 2 1/2 in. long: petioles 1/5 in. long: fr. Narrowly obovate, 1/2 in. long. Eu. G.C. III. 50:408, 409; 51:235. R.F.G. 12:660.—U. Plotii, Druce -U. minor.—U. sativa, Moss—U. minor. —U. Verschaffeltii, Hort.-Zelkova Verschaffeltii.—U. Wilsoniana, Schneid. Tree, to 50 ft.: young branchlets pubescent, later brown and often corky: lvs. elliptic or elliptic-obovate, doubly serrate, smooth above, finely pubescent or nearly glabrous beneath, 1 1/2 – 4 in. long: fr. obovate with the nutlet near the apex, glabrous, about 3/4 in. long. Cent. China. CH
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Pests and diseases
Dutch elm disease devastated elms throughout Europe and North America in the second half of the 20th century. It is caused by a micro-fungus transmitted by two species of Scolytus elm-bark beetle which act as vectors. The disease affects all species of elm native to North America and Europe, but many Asiatic species have anti-fungal genes and are resistant.
Species, varieties, forms
- "Mountain elms": spring flowering; flowers subsessile; leaves usually rough above.
- Ulmus bergmanniana - Bergmann's Elm
- Ulmus boissieri
- Ulmus castaneifolia - Chestnut-leafed Elm
- Ulmus changii
- Ulmus chumlia
- Ulmus elongata
- Ulmus gaussenii - Anhui Elm
- Ulmus glabra - Wych Elm, Scots Elm,
- Ulmus glaucescens - Gansu Elm
- Ulmus laciniata - Manchurian Elm, Cut-leaf Elm
- Ulmus laciniata var. nikkoensis - Nikko Elm
- Ulmus lamellosa - Hebei Elm
- Ulmus macrocarpa - Large-fruited Elm
- Ulmus mexicana - Mexican Elm
- Ulmus microcarpa
- Ulmus prunifolia
- Ulmus rubra - Slippery Elm, Red Elm
- Ulmus uyematsui - Arishan Elm
- Ulmus wallichiana - Himalayan Elm, Kashmir Elm
- "Field elms": spring flowering; flowers subsessile; leaves usually smooth above.
- Ulmus canescens - Grey Elm, Grey-leafed Elm, Hoary Elm
- Ulmus chenmoui - Chenmou Elm
- Ulmus davidiana - David Elm, Father David's Elm
- Ulmus harbinensis
- Ulmus ismaelis
- Ulmus lanceifolia
- Ulmus minor - Field Elm
- Ulmus procera - English Elm, Atinian Elm
- Ulmus pseudopropinqua
- Ulmus pumila - Siberian Elm
- Ulmus szechuanica - Szechuan Elm
- Ulmus villosa - Cherry Bark Elm
- "White elms": spring flowering; flowers pedunculate
- "Autumn-flowering elms": autumn flowering.
- Standard Cyclopedia of Horticulture, by L. H. Bailey, MacMillan Co., 1963