Alnus glutinosa

(Linnaeus) Gaertner

Fruct. Sem. Pl. 2: 54. 1790.

Common names: Black alder European alder
Basionym: Betula alnus var. (a) Linnaeus Sp. Pl. 2: 983. 1753
Treatment appears in FNA Volume 3.

Trees, to 20 m; trunks often several, crowns narrow. Bark dark-brown, smooth, becoming darker and breaking into shallow fissures in age; lenticels pale, horizontal. Winter buds stipitate, ellipsoid to obovoid, 6–10 mm, apex obtuse; stalks 2–5 mm; scales 2–3, outer 2 equal, valvate, usually heavily resin-coated. Leaf-blade obovate to nearly orbiculate, 3–9 × 3–8 cm, leathery, base obtuse to broadly cuneate, margins flat, coarsely and often irregularly doubly serrate to nearly dentate, major teeth acute to obtuse or rounded, apex often retuse or obcordate, or occasionally rounded; surfaces abaxially glabrous to sparsely pubescent, often more heavily on veins, both surfaces heavily resin-coated. Inflorescences formed season before flowering and exposed during winter; staminate catkins in 1 or more clusters of 2–5, 4–13 cm; pistillate catkins in 1 or more clusters of 2–5. Flowering before new growth in spring. Infructescences ovoid to nearly globose, 1.2–2.5 × 1–1.5 cm; peduncles 1–10 (–20) mm. Samaras obovate, wings reduced to narrow, thickened ridges. 2n = 28.


Phenology: Flowering early spring.
Habitat: Stream banks, moist flood plains, damp depressions, borders of wetlands
Elevation: 0–200 m

Distribution

V3 733-distribution-map.gif

Ont., Conn., Ill., Ind., Iowa, Mass., Mich., Minn., N.J., N.Y., Ohio, Pa., R.I., Wis., Europe

Discussion

Alnus glutinosa is cultivated as an ornamental tree throughout eastern North America and is available in a variety of cultivars, including cut-leafed and compact-branching forms. This species has also been used extensively to control erosion and improve the soil on recently cleared or unstable substrates, such as sand dunes and mine spoils. It has escaped and become widely naturalized throughout the temperate Northeast, occasionally becoming a weedy pest. In Europe the black alder has served for many centuries as an important source of hardwood for timbers and carved items, including wooden shoes.

Alnus glutinosa has been called A. vulgaris Hill in some older literature; that name was not validly published.

Selected References

None.

Lower Taxa

None.

"persistent" is not a number.

... more about "Alnus glutinosa"
Rounded (?) +, Obcordate (?) +, Retuse (?) +  and Obtuse (?) +
John J. Furlow +
(Linnaeus) Gaertner +
tanniferous +  and furrowed +
darker +  and dark-brown +
exfoliating +
obtuse +  and broadly cuneate +
Betula alnus var. (a) +
2 (?) +  and 3 (?) +
Ellipsoid (?) +  and Obovoid (?) +
0.6 cm6 mm <br />0.006 m <br /> (1 cm10 mm <br />0.01 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 /> (13 cm130 mm <br />0.13 m <br />) +
Black alder +  and European alder +
multibracteate +
Ont. +, Conn. +, Ill. +, Ind. +, Iowa +, Mass. +, Mich. +, Minn. +, N.J. +, N.Y. +, Ohio +, Pa. +, R.I. +, Wis. +  and Europe +
0–200 m +
pistillate +  and staminate +
reduced +  and small +
small +  and large +
Stream banks, moist flood plains, damp depressions, borders of wetlands +
1.2 cm12 mm <br />0.012 m <br /> (2.5 cm25 mm <br />0.025 m <br />) +
ovoid +  and nearly globose +
1 cm10 mm <br />0.01 m <br /> (4 cm40 mm <br />0.04 m <br />) +
1 cm10 mm <br />0.01 m <br /> (1.5 cm15 mm <br />0.015 m <br />) +
membranaceous +  and leathery +
3 cm30 mm <br />0.03 m <br /> (9 cm90 mm <br />0.09 m <br />) +
3 cm30 mm <br />0.03 m <br /> (8 cm80 mm <br />0.08 m <br />) +
3-ranked +  and nearly 2-ranked +
often irregularly doubly serrate +  and nearly dentate +
1 cm10 mm <br />0.01 m <br /> (2 cm20 mm <br />0.02 m <br />) +
0.1 cm1 mm <br />0.001 m <br /> (1 cm10 mm <br />0.01 m <br />) +
not obvious +  and defined +
membranaceous +
Flowering early spring. +
2(-3)-carpellate +
Fruct. Sem. Pl. +
1-seeded +  and 2-winged +
crowded +  and imbricate +
deciduous +  and persistent +
2 +  and 3 +
expanding +
thicker +  and thin +
0.2 cm2 mm <br />0.002 m <br /> (0.5 cm5 mm <br />0.005 m <br />) +
nearly +  and distinct +
resin-coated +
abaxially glabrous;sparsely pubescent +
Alnus glutinosa +
species +
acute +  and obtuse or rounded +
excurrent +  and deliquescent +
differentiated +  and uniform +
reduced to narrow +
tanniferous +
light +  and white +