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Smooth Alder Alnus serrulata


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Smooth Alder, fruit and leaves
credit: homeredwardprice (Homer Edward Price)/CCSA

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Alternate name: Brookside Alder, Tag Alder

Family: Betulaceae, Birch view all from this family

Description This thicket-forming shrub is native to eastern North America and can be found found from western Nova Scotia and southern New Brunswick south to Florida and Texas.

The Alnus serrulata is a large shrub or small tree that may grow up to 2.5-4 m (8-12 ft) high and 15 cm (6 in) in diameter. The scientific name originates from alnus which is an old name for alder; serrulata points to the finely-toothed leaf margins which it possesses. It takes about 10 yrs to mature. The plant prefers moist soil near streams, pond margins, and riversides. It usually has multiple stems from its base and reddish-green flowers. The broad, flat, dark green leaves are about 2 to 4 inches long.

Leaf: The simple, round leaves are obovate, 2 to 5 in long, 1.2 to 2.8 in wide, obtuse, wider at middle, and V-shaped base. Veins are pinnate and conspicuous. Leaves have a smooth texture above and hairy texture below. The upper side of the leaves are dark green and the undersides are pale green.

Flower: The flowers are monoecious, meaning that both sexes are found on a single plant. Male (Staminate) catkins are 1.6-2.4 in long; female (Pistillate) catkins are 1/2 in long. Reddish-green flowers open in March to April.

Fruit: The ovate, dark brown, cone-like fruit is hard with winged scales. Seeds are produced in small cones and do not have wings. Fruit usually matures during fall and is quite persistent.

Twig: The twigs are reddish-brown and have a 3-angled-pith; young twigs are covered with hairs.

Bark: The bark is brownish gray, smooth, and has a bitter and astringent taste.

Habitat Swamps (fresh & salt), Watersides (fresh).

Range New England, Plains, Mid-Atlantic, Southeast, Texas, Eastern Canada, Great Lakes, Florida.

Comments Physiological problems are rare, however the wood is weak and breakage is common. Very flood tolerant. Alders fix nitrogen and thus serve as nutrient-giving pioneers in reclamation projects.

Exposure Preference Sun.

Flower March

Native Distribution N. Florida to e. Texas, n. to s.w. Nova Scotia (locally), c. Maine, c. Vermont, Ohio, s. Illinois, & s.e. Missouri

Site Preference Stream banks; bogs; swamp borders; wet meadows

Soil Preference Wet, fine sandy loams, peats & mucks. pH 5.5-7.5.

Wildlife Value An intermediate source of food for wildlife.