Betula microphylla Bunge

Described from the Altai mountains, Betula microphylla is one of numerous isolated birch populations in the mountains of central Asia that have been described as separate species (see the entry for Betula tianschanica). In the wild it forms a small tree, often with several stems. Its small, few-veined leaves and very white-warty twigs greatly resemble those of B. humilis, which may have contributed one of the genomes to this tetraploid species, though a possible hybrid origin might perhaps involve B. fruticosa and/or B. pubescens, each of which this species resembles in certain characters. Moving from the Altai through the Tian Shan there seems to be no clear distinction between B. microphylla and B. tianschanica. Betula halophila was described from saline areas in Balibagi of the lower reaches of the Kelang River, Altay County, Xinjiang, China.

The species is very rare in cultivation. As it originates in an extreme continental climate, it has not grown well in the British Isles, forming only a straggly small tree with several stems and suffering severe winter dieback of twigs, especially in the lower part of the canopy. Only the most vigorous shoots exposed to the strongest sunlight mature sufficiently to survive most winters.