Jepson eFlora
Key to families | Table of families and genera

Key to Alnus

View taxon page for Alnus

(For a list of species in Alnus, use the above link.)

Jepson Manual glossary definitions can be seen by moving your cursor over words underlined with dots.

1. Tree, > 9 m, not forming thickets

2. Leaf blade adaxially shiny, base cordate to truncate ..... [A. cordata]

2' Leaf blade adaxially dull, base rounded to tapered

3. Leaf margin generally serrate, not tightly rolled under ..... A. rhombifolia

3' Leaf margin doubly serrate, tightly rolled under ..... A. rubra

1' Shrub, < 9 m, forming thickets

4. Lateral buds stalked, scales 0; pedicels < cone-like catkins; leaf thick, margin doubly serrate to crenate, teeth pointed, blunt, or rounded ..... A. incana subsp. tenuifolia

4' Lateral buds sessile, scales present; pedicels > cone-like catkins; leaf thin to firm, margin serrate, teeth pointed ..... A. viridis

5. Blade firm, adaxially dark green, margins generally densely serrate; coastal, 0–500 m ..... subsp. fruticosa

5' Blade thin, adaxially yellow-green, margins coarsely doubly serrate; montane, 1000–2700 m ..... subsp. sinuata


Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.