Betula medwediewii Regel

Betula medwediewii is a shrubby birch with large leaves, long male catkins and rich yellow autumn foliage. Bean (1976) described it as a handsome bush with alder-like leaves […] very striking in winter with its glossy, pale brown stems and large buds.’ It is clearly distinguished from all other birches by its thick, stiff twigs with large, ovate to circular leaves, and large, upright, persistent fruiting catkins with brown scales. The fruiting catkins are mostly borne on shoots on the outside of the shrub, so that they occur in groups along shoots sticking out from the shrub. These shoots usually die after fruiting, as no buds are formed in the axils of the leaves of the fruiting spur shoots. The twigs, when scraped, smell of oil of wintergreen.

Described by Eduard Regel from specimens collected in the Caucasus in 1886 by Jakob Medvedev (1847–1923), Betula medwediewii is one of a group of rare relict trees and shrubs found in the western Transcaucasus and the adjacent mountains of north-eastern Turkey (Melville 1939; Eminagaoğlu et al. 2006; Browicz 1975). It grows on the upper margins of Picea orientalis forest, and in subalpine scrub, often accompanied by other rarities such as Epigaea gaultherioides, Quercus pontica and Rhododendron ungernii, as for example in the Mtirala reserve and in the Korolistzkhali river gorge near Batumi (Dmitrieva 1960). Betula islandica, a subfossil birch described from leaves and fruiting catkin scales in mid-Miocene deposits in Iceland, is apparently similar in appearance to (Denk, Grímsson & Kvacek 2005).

Apart from the even rarer Caucasian Betula megrelica, B. medwediewii is probably most closely related to B. alleghaniensis, the Yellow Birch, of eastern North America, and to B. kweichowensis (syn. B. insignis) of central China. However, these east Asian and North American species are large, moisture-requiring trees whereas B. medwediewii is a drought-tolerant mountain shrub.

Betula medwediewii is occasionally grown in arboreta and a few large gardens, where it forms a large shrub, or – if grown on a single stem – a goblet-shaped small tree that develops beautiful golden yellow autumn colour, the leaves remaining on the tree for some time. Though slow-growing as a seedling, it is easy to grow and (as a mountain plant) is tolerant of exposure and very hardy. Betula medwediewii is self-compatible and isolated trees bear fertile seed that comes true; the species does not hybridise with other birches, perhaps because it flowers later than other species of Betula,and perhaps also because it is rarely grown alongside other species of its section (its chromosome number, 2n=140, differs widely from that of most other birches).

Bean (1976) reported that the species was introduced to Kew from Tblisi in 1897, and offered commercially by Späth of Berlin from 1906. A collection made by Peter Davis (D 32343) in Turkey, near Çoruh grows at RBG Edinburgh. At Westonbirt there are a pair of grafted Betula medwediewii planted by Mitchell in 1938, presumably grown on B. pendula rootstocks. The unusual size of the trees – far larger than is usual in their seed-grown counterparts – is plausibly attributable to the effect of the stock: if a low spreading habit is desired then care should be taken to source plants grown instead from seed or cuttings.