Bogs and Acidic Peatlands of Southern New England by Marsha C. Salett
Alnus serrulata (Ait.) Willd.
BETULACEAE (Birch Family)
EtymologyAlnus is the classical Latin name for alder; serrulata means minutely saw-toothed, from serra, Latin for saw.
Synonyms (Common Name)Common Alder
DescriptionA deciduous, broad-leaved shrub or small tree, smooth alder grows to 20' tall. They have multiple trunks and form dense thickets. The dark gray bark is sometimes dotted with tiny lenticels. Alders have shallow, matted root systems that help prevent erosion and enrich soil in association with nitrogen-fixing bacteria that are harbored in the root nodules. Wetland indicator status: OBL
Wetland indicator statusOBL
Plant Heightto 20 feet
LeavesDeciduous, alternate, simple, with finely toothed margins (rarely wavy), 2-3 " long; elliptical to obovate, usually widest above the middle, with wedge-shaped (or slightly rounded) base; underside smooth and green.
Flower/InflorescenceMale and female flowers different; clustered in catkins at tips of separate branches. Male catkins: reddish, elongate (to 1"), drooping. Female catkins: ovoid, erect, 3/8 -- 3/4" long, brown and woody when mature; they look like miniature pinecones.
Flowering PeriodMarch-May, before leaves appear Male and female catkin buds develop in autumn and persist over the winter; buds are covered with 2-3 equal scales
FruitTiny achene (nutlet) in axils of cone-like female catkin.
Fruiting PeriodAugust-October; mature cones persist throughout winter.
HabitatMarshes, shrub swamps, margins of lakes, ponds, and rivers.
RangeNova Scotia and Quebec to Missouri, south to Florida and Texas.
(c) 1998-2006 Marsha C. Salett