Ulmus davidiana var. japonica
| Ulmus davidiana var. japonica | |
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| Japanese elm, Sapporo | |
| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Rosids |
| Order: | Rosales |
| Family: | Ulmaceae |
| Genus: | Ulmus |
| Species: | U. davidiana |
| Trinomial name | |
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Ulmus davidiana var. japonica Rehder |
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| Synonyms | |
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Ulmus davidiana var. japonica, the Japanese elm, is one of the larger and more graceful Asiatic elms, endemic to much of continental north-east Asia and Japan, where it grows in swamp forest on young alluvial soils, although much of this habitat has now been lost to intensive rice cultivation.
The size and shape of the Japanese elm is extremely variable, ranging from short and bearing a densely branched broad crown similar to the Wych elm to tall, single-stemmed, with narrow crown similar to the English elmAugustine Henry described one of the latter outside Iwamigawa, Hokkaido, railway station as being 34 m tall, with a clean stem to a height of approximately 15 m. Japanese elm is distinguished by the fawn colour of shoots at the end of their first season, the shoots often being roughened by minute terbercles or 'warts'. The young shoots often bear corky wings, similar to those of the European field elm U. minor, to which it is closely related. The leaves are generally obovate, < 11 cm long, and with a coarse upper surface. Like many of the European field elms, var. japonica retains its green foliage well into the autumn, before a late display of deep yellow. Bean noted that the variety from western China, formerly known as U. wilsoniana, has 16 to 22 pairs of leaf-veins, while the eastern type tree has not more than 16. The perfect, apetalous wind-pollinated flowers emerge in early spring, before the leaves. The samara, <15 mm long, is obovate to orbicular, occasionally hairy over its entire surface but more often glabrous, the seed touching the notch, the inner margins of which are ciliate, the stigmas being slightly incurved. Trees grown from seed at Great Fontley in southern England first flowered aged 13 years.
Japanese elm, showing pendulous habit of lower branchlets. SHHG, Romsey, UK
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Wikipedia