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FNA | Family List | FNA Vol. 3 | Betulaceae | Alnus

8. Alnus maritima (Marshall) Muhlenburg ex Nuttall, N. Amer. Sylv. 1: 34. 1842.

Seaside alder, brook alder

Betula-alnus maritima Marshall, Arbust. Amer., 20. 1785

Shrubs or trees , to 10 m; crowns narrow. Bark light gray, smooth; lenticels small, inconspicuous. Winter buds stipitate, ovoid to ellipsoid, 2.5--5 mm, apex rounded; stalks 1--3 mm; scales 2--3, subequal, often poorly developed, heavily resin-coated. Leaf blade narrowly elliptic, oblong, or narrowly obovate, 4.5--9 × 2--5 cm, leathery, base acute to cuneate, margins flat, teeth low, single, relatively distant, apex acute, obtuse, or rounded; surfaces abaxially mostly glabrous, resin-coated when young. Inflorescences: catkins formed during same season as flowering; staminate catkins in 1 terminal cluster of 2--4, 2--6 cm; pistillate catkins solitary in leaf axils proximal to staminate catkins. Flowering in late summer or early fall. Infructescences ovoid, 1.2--2.8 × 1.2--2.2 cm; peduncles 5--10 mm. Samaras elliptic, wings reduced to narrow, leathery ridges. 2 n = 28.

Flowering late summer--early fall. Along edges of ponds and small streams, often in standing water; 0--100 m; Del., Md., Okla.

Alnus maritima consists of widely disjunct populations in Delaware, Maryland, and southern Oklahoma. The populations probably represent remnants of Pleistocene and post-Pleistocene distributions and migrations. It is our only member of the predominantly Asian fall-blooming Alnus subg. Clethropsis.


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