Virginia Tech Dendrology

Arizona alder Betulaceae Alnus oblongifolia Torr. symbol: ALOB2
Leaf: Alternate, simple, ovate to oblong, V-shaped base, 2 to 3 1/2 inches long, doubly serrate, dark green above, paler with a few scattered hairs below particularly in leaf axils.
Flower: Species is monoecious; males are yellow-green elongated, catkins about 2 to 3 inches long, in hanging clusters; females are very small (1/4 inch) reddish green appearing in early spring.
Fruit: Cone-like, woody, 1/2 inch long, green but turning reddish brown when ripe, contains numerous small winged seeds, ripen in early fall and persist through the winter.
Twig: Slender, yellow brown with fine fuzz when young; buds are stalked, red and long up to 1/2 inch.
Bark: Gray-brown and smooth with numerous short lenticels when young, later developing rectangular, flat narrow plates a bit scaly.
Form: An upright medium sized tree with a narrow crown reaching up to 70 feet in height.
Looks like: red alder - white alder - European black alder - Italian alder

Additional Range Information: Alnus oblongifolia is native to North America. Range may be expanded by planting. Download the full-size PDF map.
External Links: USDA Plants Database - USDAFS Forest Products Lab
All material 2025 Virginia Tech Dept. of Forest Resources and Environmental Conservation; Photos and text by: John Seiler, Edward Jensen, Alex Niemiera, and John Peterson; Silvics reprinted from Ag Handbook 654; range map source information