Alder Tree Identification: Cones, Catkins, Leaves, Bark

Alder tree identification rests on three features, according to Oregon State University's Trees of the Pacific Northwest:

• Leaves: alternate and egg-shaped, with serrated or doubly serrated edges.
• Cones: small woody cones about 1 inch long that stay on the tree through winter. These are the easiest mark from a distance, and no other common broadleaf tree carries little "pine cones".
• Setting: alders are commonly found in moist areas next to water.

In early spring, The Tree Grower (UK) notes flowers appear before the leaves: long male catkins about 5 to 10 cm that turn yellow as they shed pollen, and small purple female catkins that become the cones. Its bark is grayish and becomes fissured and rough as the trunk grows.

Oregon State says eight alders are native to North America and four grow in Oregon, only two of them commonly reaching tree size:

• Red alder: a large tree, 40 to 80 feet, single trunk; leaf edges tightly rolled under. It is the only abundant alder in the region.
• White alder: also a large tree, 40 to 80 feet, single trunk; leaf edges not rolled under.
• Sitka alder: a shrub or small tree under 25 feet with several trunks; very finely serrated leaf edges.
• Thinleaf alder: a shrub or small tree under 25 feet with several trunks; a double set of coarse teeth on the leaf edge.

Run a finger along the leaf edge: a rolled-under margin means red alder.

Wikipedia describes red alder bark as mottled, ashy gray and smooth, often covered with white lichen and moss, so trunks can look almost white. The name comes from the bright rusty red color that develops when the bark is bruised or scraped, a quick field test. It grows from Southeast Alaska to central coastal California, and the tallest recorded tree, in Oregon, reached 32 meters.

• Speckled alder (Alnus incana subsp. rugosa) grows across much of Canada below the tree line and the northeastern US, usually as a multi-stemmed shrubby tree in wet ground. Leaves are dull green, egg-shaped, 5 to 11 cm long (Wikipedia). Deer and moose browse it and birds eat the seeds.
• Common alder (Alnus glutinosa) of Britain and Europe has young leaves that are sticky to the touch, and mature leaves that are rounded with a notched rather than pointed tip. Its seeds have corky, air-filled wings that float, and its cones mature in October and often stay on through winter (The Tree Grower).

Alder and birch are not the same tree, but they are in the same family, Betulaceae. Wikipedia gives the difference that settles it: alder's female catkins become woody and do not fall apart when ripe; they open like small conifer cones to release seeds. Birch catkins break up. So a tree with last year's tiny brown cones still hanging on is an alder. Bark helps too: many birches have peeling bark (see birch tree identification), while red alder bark is smooth and blotched with lichen.

The names sound alike but the plants are unrelated. Elder (Sambucus, also called elderberry) is in a different family, Viburnaceae. Wikipedia describes elder as a fast-growing shrub or small tree 3 to 10 meters tall with opposite, compound leaves of 5 to 9 leaflets, flat clusters of small white or cream flowers, and black, blue-black or red berries. Alder has alternate, simple leaves and woody cones. Wikipedia also notes that some elder species have toxic berries, leaves, roots and stems, so do not eat elderberries on the strength of an identification alone.

Alders enrich soil with nitrogen much as legumes do (Oregon State). Wikipedia explains that they host the nitrogen-fixing bacterium Frankia alni, and that red alder can add 130 to 320 kg of nitrogen per hectare a year, which makes alders pioneer trees on bare or disturbed ground. The wood is used for smoking salmon and other foods, electric guitar bodies, furniture and cabinets, and historically for the pilings under Venice (Wikipedia; The Tree Grower). The name comes from Old English alor.

Photograph a branch with cones and catkins, a leaf edge close up (rolled under or flat, single or double teeth), the bark, and the setting by water. Photograph it and the app identifies it, with free scans every day.

Research and drafting for this page used AI assistance. Every measurement, date, price and claim was then checked against the sources listed below, which were opened and read on 2026-09-25. Where two sources give different numbers, both are shown.