Alder Tree Identification

Types

• Several types of alder trees grow in the U.S., including red, white, Sitka and thinleaf varieties. These varieties can grow between 25 and 80 feet tall, depending on their type and geographical location. Altogether, there are 8 species of alder trees in the United States, several of which make their home in Oregon. The black alder is common in Scotland, Ireland and Central Europe.

Habitat

• Alder trees are commonly found in the Pacific Northwest and Canada. They like to grow near water sources, such as the lakes, streams and creeks common to Washington and Oregon. They prefer moist soil and environments. Depending on moisture and rain levels, some areas offer more abundant growth of alder trees than others do. The alder grows straight and in a slightly cone-shaped formation, with a relatively narrow canopy, often reaching more than 50 feet in height. The red alder grows in even the poorest, rocky soils, but prefers sandy and well-drained loam.

Bark

• The bark of alder trees has long been used in medicine and folklore in the Pacific Northwest region and in other areas around the world where they grow. Alder bark is thin and ranges in color from a light gray to brown. The bark of the black or common alder tree is a deep gray, often fissured. The inner tree bark is red-brown.

Leaves

• The leaves of most varieties of alder trees are small, rounded and deep green. Many alder leaves form a heart shape or are nearly oval in structure. Some have relatively smooth edges, such as the black alder, while others have slightly jagged edges, such as the gray alder. The European alder has clusters of rounded leaves ranging from 2 to 5 inches in length with parallel veins, growing in groups of 6 to 8 on the ends of branches. During autumn months, the leaves of most varieties of alder trees display very little coloration.

Cones

• The fruit or cone of the alder tree is small and conical, similar in size to a large berry. When mature, the small cones may grow to 1 inch in length with relatively smooth sides. The cones start out with a light brown and greenish color, then ripen to a reddish brown.