Alnus incana subsp. tenuifolia

(Nuttall) Breitung

Amer. Midl. Naturalist 58: 25. 1957.

Common names: Thinleaf alder mountain alder
Endemic
Basionym: Alnus tenuifolia Nuttall N. Amer. Sylv. 1: 48. 1842
Synonyms: Alnus incana var. occidentalis (Dippel) C. L. Hitchcock Alnus incana var. virescens S. Watson Alnus occidentalis Alnus rugosa var. occidentalis (Dippel) C. L. Hitchcock
Treatment appears in FNA Volume 3.

Shrubs or trees, to 12 m; shrubs ascending, open, spreading, trees small, shrubby. Bark light gray to dark-brown, smooth; lenticels pale, orbiculate to elliptic. Winter buds nearly divergent, ellipsoid, 4–7 mm, apex obtuse; stalks 1–3 mm; scales 2, equal, valvate. Leaf-blade ovate to elliptic, 4–10 × 2.5–8 cm, thin, base broadly cuneate to rounded, margins distinctly doubly serrate to nearly crenate or lobulate, teeth relatively blunt or rounded, apex acute to obtuse; surfaces abaxially glabrous to sparsely pubescent, slightly to not noticeably resin-coated. Inflorescences: staminate catkins in 1 or more clusters of 3–5, 4–10 cm; pistillate catkins in 1 or more clusters of 2–5. Infructescences ovoid, 1–2 × 0.8–1.3 cm; peduncles 1–5 mm. 2n = 28.


Phenology: Flowering early spring.
Habitat: Stream banks, lake shores, margins of wet fields and meadows, bog margins, and muskegs
Elevation: 100–3000 m

Distribution

V3 386-distribution-map.gif

Alta., B.C., N.W.T., Sask., Yukon, Alaska, Ariz., Calif., Colo., Idaho, Mont., Nev., N.Mex., Oreg., Utah, Wash., Wyo.

Discussion

Alnus incana subsp. tenuifolia is somewhat more treelike than the eastern A. incana subsp. rugosa, from which it also differs in leaf shape, leaf margins, and other characters. It is a frequent component of streamside vegetation throughout the Rocky Mountains and other mountainous parts of western North America.

Native Americans used alnus incana subsp. tenuifolia medicinally for pains in the lungs or hips, for scrofula, as a laxative, and as a diuretic for gonorrhea (D. E. Moerman 1986).

Selected References

None.

Lower Taxa

None.

No values specified."persistent" is not a number.

Acute (?) +  and Obtuse (?) +
John J. Furlow +
(Nuttall) Breitung +
tanniferous +  and furrowed +
light gray +  and dark-brown +
exfoliating +
broadly cuneate +  and rounded +
Alnus tenuifolia +
2 (?) +  and 3 (?) +
0.4 cm4 mm <br />0.004 m <br /> (0.7 cm7 mm <br />0.007 m <br />) +
pistillate +  and staminate +
in relatively small racemose clusters +  and solitary +
solitary +, cluster +  and racemose +
erect +  and nearly pendulous +
proximal +  and lateral +
enclosed in buds +  and exposed +
ovoid +  and ellipsoid +
expanding +
4 cm40 mm <br />0.04 m <br /> (10 cm100 mm <br />0.1 m <br />) +
Thinleaf alder +  and mountain alder +
multibracteate +
Alta. +, B.C. +, N.W.T. +, Sask. +, Yukon +, Alaska +, Ariz. +, Calif. +, Colo. +, Idaho +, Mont. +, Nev. +, N.Mex. +, Oreg. +, Utah +, Wash. +  and Wyo. +
100–3000 m +
pistillate +  and staminate +
reduced +  and small +
small +  and large +
Stream banks, lake shores, margins of wet fields and meadows, bog margins, and muskegs +
1 cm10 mm <br />0.01 m <br /> (2 cm20 mm <br />0.02 m <br />) +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
0.8 cm8 mm <br />0.008 m <br /> (1.3 cm13 mm <br />0.013 m <br />) +
membranaceous +  and leathery +
4 cm40 mm <br />0.04 m <br /> (10 cm100 mm <br />0.1 m <br />) +
3-ranked +  and nearly 2-ranked +
orbiculate;elliptic +
unexpanded +  and enlarged +
distinctly doubly serrate +  and nearly crenate or lobulate +
0.1 cm1 mm <br />0.001 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
not obvious +  and defined +
membranaceous +
Flowering early spring. +
2(-3)-carpellate +
Amer. Midl. Naturalist +
1-seeded +  and 2-winged +
elliptic;obovate +
crowded +  and imbricate +
resin-coated +
deciduous +  and persistent +
expanding +
thicker +  and thin +
0.1 cm1 mm <br />0.001 m <br /> (0.3 cm3 mm <br />0.003 m <br />) +
nearly +  and distinct +
resin-coated +
abaxially glabrous;sparsely pubescent +
Alnus incana var. occidentalis +, Alnus incana var. virescens +, Alnus occidentalis +  and Alnus rugosa var. occidentalis +
Alnus incana subsp. tenuifolia +
Alnus incana +
subspecies +
rounded +  and blunt +
excurrent +  and deliquescent +
differentiated +  and uniform +
tree +, shrubby +  and shrub +
spreading +  and ascending +
irregular +
narrower +
tanniferous +
light +  and white +