Aquatic and Wetland Vascular Plants of the Northern Great Plains
11. Betulaceae, the Birch Family
2. Betula L. -- Birch1. Betula glandulosa Michx. -- Dwarf birch, swamp birch
Erect, colonial shrub to 2 m tall; bark dull gray; twigs grayish-puberulent and dotted with resin glands, becoming reddish-brown and pruinose with age. Leaves dark green above, paler below, suborbicular to obovate, 20-35(70) mm long, 10-25(50) mm wide, glabrous with age, coarsely serrate, the teeth blunt or sharp; petioles 3-6 mm long; stipules caducous, ovate, 2-2.5 mm long, ciliate. Catkins produced singly from the buds; male catkins sessile, cylindric, 15-18 mm long, 1-2.5 mm thick; female catkins on peduncles 3-10 mm long, the peduncle often bearing a single petioled, toothed bract, the catkin cylindric, 7-18 mm long, ca. 5 mm thick; scales 3-lobed. Nutlets flat, winged, suborbicular to obovate, 1.5 mm long, 1.2-2 mm wide. Flowering late May--mid Jun, fruiting late Jul--Aug. Swamps, cold springs, bogs, seepage areas and stream banks; occasional in e and c ND, uncommon in the Black Hills; (Newf. to AK, s to ME, n NY, IN, Ont., MN, SD, WY, ID and CA). B. glandulifera (Regel) Butler; B. pumila L. var. glandulifera Regel.
The phase of B. glandulosa in our area is var. glandulifera (Regel) Gl., characterized by resinous young leaves and twigs and catkins with scales averaging larger (3-4.5 mm long) than in the typical variety.
In the Black Hills, Betula papyrifera Marsh., paper birch, and B.
occidentalis Hook., mountain or water birch, are often closely associated
with streams. B. occidentalis in particular is common on low banks
of Black Hills streams. Both of these birches are easily distinguished from
bog birch. The peeling white bark and arborescent habit of paper birch are
distinctive. Mountain birch is a large shrub or small tree with ovate leaves
and lustrous, bronzy, nonpeeling bark. Although both paper and mountain birch
are found in other parts of our range, only in the Black Hills are they so
consistently found next to water.
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