Betula neoalaskana Sarg.

Common names

Yukon White Birch

Synonyms

B. alaskana Sarg., not Lesquereux; B. papyrifera var. humilis (Reg.) Fern. & Raup; B. alba subsp. papyrifera var. humilis Reg. emend. Fern.; B. resinifera (Reg.) Britt., sensu Britt., in part, not B. alba subsp. verrucosa var. resinifera Reg.

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Bean

A tree usually under 50 ft high; bark white or pale brown, not peeling freely; young shoots usually thickly covered with viscid warts, not downy. Leaves triangular-ovate cuneate or truncate at the base, coarsely and often doubly toothed, glossy dark green and at first viscid above, sometimes finely downy on the veins beneath; petioles slender, about 1 in. long, often reddish. Fruiting catkins cylindric, to about 114 in. long; bract scales hairy at the margin, the central lobe long-pointed, the laterals spreading.

Native of Alaska and the Yukon, thence south-east through Alberta and Saskatchewan to Manitoba, said by Sargent to be the common birch of the Yukon valley. It was introduced to Kew in 1905, but the present example is of later date.

B. neoalaskana is of interest in showing considerable resemblance, at least in foliage and its glandular twigs, to the white birches of eastern Asia. This led the American botanist Britton to identify it with Regel's B. alba subsp. verrucosa var. resinifera, the type of which is a specimen collected by Middendorf near Udskoye in the Russian Far East, at the same time raising this variety to the level of species as B. resinifera (Reg.) Britt. But this would be a name for the Yukon white birch only if it were indeed conspecific with Regel's birch, which is certainly not the case. So although B. resinifera has priority over B. neoalaskana, the notion that it can be regarded as a new name with an American type is quite erroneous. Furthermore, it is antedated by B. resinifera Royle (1839), applied to a Himalayan birch of uncertain identity.