Betula pumila

Linnaeus

Mant. Pl., 124. 1767

Common names: Bog birch dwarf birch bouleau nain
Endemic
Synonyms: Betula borealis Spach Betula glandulifera (Regel) B. T. Butler Betula glandulosa var. glandulifera (Regel) Gleason Betula glandulosa var. hallii (Howell) C. L. Hitchcock Betula hallii Linnaeus Betula nana var. glandulifera (Regel) B. Boivin Betula pubescens subsp. borealis (Spach) A. Löve & D. Löve Betula pumila var. glabra Regel Betula pumila var. glandulifera Regel Betula pumila var. renifolia Fernald
Treatment appears in FNA Volume 3.
Shrubs, coarse, irregular, or spreading, to 4 m. Bark dark reddish brown, smooth, close; lenticels pale, inconspicuous. Twigs without taste and odor of wintergreen, glabrous to moderately pubescent, with scattered small resinous glands, especially near nodes. Leaf blade elliptic, obovate, or nearly orbiculate (to sometimes reniform) with 2–6 pairs of lateral veins, 2.5–5(–7) × 1–5 cm, base cuneate to rounded, margins crenate to dentate, apex usually broadly acute or obtuse to rounded; surfaces abaxially glabrous or slightly pubescent to heavily velutinous or tomentose, often with scattered resinous glands. Infructescences erect, cylindric, 0.8–1.5(–2) × 0.8–1 cm, shattering with fruits in fall; scales glabrous to pubescent, lobes diverging slightly distal to middle, central lobe narrow, elongate, lateral lobes shorter and broader, extended. Samaras with wings slightly narrower than body, broadest near center, not extended beyond body apically. 2n = 56.

Phenology: Flowering late spring.
Habitat: Bogs, calcareous fens, wooded swamps, muskegs, lake shores
Elevation: 0–700 m

Distribution

V3 681-distribution-map.gif

St. Pierre and Miquelon, Alta., B.C., Man., N.B., Nfld., N.W.T., N.S., Ont., P.E.I., Que., Sask., Yukon, Calif., Colo., Conn., Idaho, Ill., Ind., Iowa, Kans., Maine, Mass., Mich., Minn., Mont., Nebr., N.J., N.Y., N.Dak., Ohio, Oreg., Pa., S.Dak., Vt., Wash., Wis., Wyo.

Discussion

Betula pumila is sometimes treated (in part) as a variety of B. glandulosa Michaux, to which it is related at a subgeneric or sectional level. On the basis of morphology, however, it forms a cohesive and distinct entity (J. J. Furlow 1984). The two main varieties into which B. pumila is often divided (a more southern B. pumila </i>var.<i> pumila, with mostly pubescent, glandless leaves, and a more northern B. pumila </i>var.<i> glandulifera, with less pubescent, gland-bearing leaves) may represent geographic races; these are not well marked, however, and they do not hold up well when the complex is examined as a whole.

The Ojibwa used Betula pumila medicinally as a gynecological aid and as a respiratory aid (D. E. Moerman 1986).

References

None.

Lower Taxa

No lower taxa listed.