Betula minor (Tuckerman) Fern.
Dwarf White Birch
Habitat: Acidic rocky barrens, peats and alpine summits of higher mountains. [Alpine or subalpine (non-forested, upland)]
Range: Labrador to Newfoundland, south to the mountains of Gaspé Peninsula, Quebec, northern New England, and northern New York.
Aids to Identification: Betula minor is an erect or irregularly spreading shrub up to 5 m with reddish brown bark. Betula minor has characters of both Betula cordifolia and B. glandulosa, thus complicating identification. The twigs are sparsley pubescent to glabrous., the leaves are coarsley doubly serrate with pubescence on the major veins. As compared to B. cordifolia, the catkins are longer, the wings of the samaras (fruit) are wider, and the flowers appear slightly earlier. Compared to Betula glandulosa, the leaves are larger, relatively more pointed, and with a subcordate base.
Ecological characteristics: This birch may have arisen through hybridization between dwarf birch (B. glandulosa) and mountain paper birch (B. cordifolia). This plant occurs on Maine’s highrest mountains.
Phenology: Flowers June - July.
Synonyms: Betula papyracea Ait. var. minor Tuckerman; Betula pubescens Ehrh. ssp. minor (Tuckerman) A. & D. Löve; Betula saxophila Lepage. Several names have been misapplied or rejected in past treatments including Betula x minor and Betula borealis Spach.
Known Distribution in Maine: This rare plant has been documented from a total of 2 town(s) in the following county(ies): Franklin, Piscataquis.
Reason(s) for rarity: Disjunct from principal range.
Conservation considerations: Populations could be threatened by heavy recreational (hiking) use.