Common in the western mountains along streams and in marshy meadows, thinleaf alder is a small tree with leaves that are both finely serrated and coarsely toothed, as well as smooth gray bark, and cone-like female catkins that stay on the branches throughout the year. Compare thinleaf alder with water birch, which grows in the same habitat but has leaves that are more oval, redder bark, and catkins that are not persistent and cone-like. Other alders in western North America include the Southwest's Arizona alder, with narrower, pointier leaves, and several species in the Pacific Northwest and in the northern Rocky Mountains: Sitka alder, with leaves that are shiny and sticky on the underside; red alder, with rusty hairs on the leaves' undersides; and white alder, with oval leaves that are dull on both sides. The eastern North American version of thin-leaf alder is speckled alder.

Mycorrhizal mushrooms associated with western alders include Floccularia albolanaripes, Gyrodon lividus, milky cap species (including Lactarius occidentalis, Lactarius cascadensis, and others), and species of Russula, among others. Saprobes include Calocybe fallax, Coprinopsis alnivora, Coprinopsis pinguispora, Inonotus radiatus, Leratiomyces percevalii, Mycena alnicola, Mycena haematopus cuspidata, Mycena roseipallens, Pholiota limonella, Pluteus leucoborealis, and many others.

thinleaf alder loves mountain streamsides . . .

. . . and high-elevation marshy meadows

leaves are both finely serrated and broadly toothed

bark is gray and fairly smooth . . .

. . . with frequent blisters

developing female (above) and male (below) catkins

female catkins are cone-like . . .

. . . becoming woody and persisting on the branches

Kuo, Michael (August, 2022). Alnus incana tenuifolia (thinleaf alder). Retrieved from the MushroomExpert.com website: www.mushroomexpert.com/trees/alnus_incana_tenuifolia.html

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