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Key to families | Table of families and genera

This text currently parallels The Jepson Manual: Vascular Plants of California, Second Edition that is now available at the University of California Press.

Text appearing in blue on this page will not appear in the printed book; it will be displayed only on the Web. Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.

 

ALNUS ALDER

Stem: trunk < 35 m; bark smooth, gray to brown; twigs glabrous to fine-hairy, red-gray; lenticels small; winter buds stalked, 0–6-scaled.
Leaf: glabrous to fine-hairy; blade 3–15 cm, cordate to elliptic or diamond-shaped.
Staminate inflorescence: 5–20 cm; bracts each subtending 3 flowers, 4 bractlets.
Pistillate inflorescence: 5–20 mm; bracts each subtending 2 flowers, 4 fused bractlets.
Staminate flower: sepals 4; stamens 1–4.
Pistillate flower: sepals 0.
Fruit: many, in cone-like catkin, not enclosed by bract, winged, bracts 3 mm, woody, persistent.
± 25 species: n hemisphere, South America. (Latin: alder) Root nodules contain nitrogen-fixing bacteria; wood used for interior finishing, to smoke fish, meats.

Key to Alnus

1. Tree, > 9 m, not forming thickets

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

2' Lf blade adaxially dull, base rounded to tapered

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

3' Lf 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

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Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [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].
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