Jepson Herbarium
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Shrub, tree; monoecious.
Stem: trunk < 35 m; bark smooth to scaly, peeling in thin layers or not, lenticels present or not.
Leaf: simple, alternate, petioled, deciduous; stipules deciduous; blade ovate to elliptic, generally serrate, generally ± doubly so.
Inflorescence: catkin, generally appearing before leaves, often clustered; bracts each subtending 2–3 flowers, 3–6 bractlets.
Staminate inflorescence: pendent, ± elongate.
Pistillate inflorescence: pendent or erect, developing variously in fruit (see key to genera).
Staminate flower: sepals 0–4, minute; petals 0; stamens 1–10; pistil vestigial or 0.
Pistillate flower: sepals 0–4; petals 0; stamens 0; pistil 1, ovary inferior or superior, chambers 2, each 1-ovuled by abortion, stigmas 2.
Fruit: achene, nut, winged or not, subtended or enclosed by 1–2 bracts.
6 genera, 155 species: generally n hemisphere; some cultivated. [Furlow 1997 FNANM 3:507–538] —Scientific Editor: Thomas J. Rosatti.

Key to Betulaceae

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.

Shrub.
Stem: trunks < 8 m.
Leaf: blade narrow- to broad- ovate, base tapered to cordate, tip acute or short- acuminate to tapered, margin ± flat, adaxially yellow-green to dark green, hairs sparse, especially on veins, moderately to heavily resinous.
Inflorescence: appearing with or before leaves. [Betula viridis Chaix] 2 other subspp. in Can, Europe. [Online Interchange]

Stem: trunks < 8 m.
Leaf: blade thin, narrow- to broad- ovate, base tapered to subcordate, tip acute to tapered, coarsely doubly serrate, adaxially yellow-green, shiny, abaxially green, glabrous or hairs restricted to or denser in major vein axils, lightly to moderately resinous.
Along creeks, seeps, meadow margins; 1000–2700 m. Klamath Ranges, Outer North Coast Ranges, High North Coast Ranges, w High Cascade Range (Grizzly Peak, Shasta Co.);

Previous taxon: Alnus viridis subsp. fruticosa
Next taxon: Betula

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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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Bioregions in which taxon occurs	Red area (if present) is the part of the bioregion lying between the upper and lower elevation limits of the taxon; markers link to CCH specimen records. If the markers are obscured, reload the page [or change window size and reload]. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
Chart based on elevation range in Manual and elevations and coordinates of CCH records. Data provided by the participants of the Consortium of California Herbaria. Note: About half of the CCH records include both elevation and coordinates.	Map made in collaboration with Scott Loarie. Data provided by the participants of the Consortium of California Herbaria. View all CCH records   CCH collections by month Duplicates counted once; synonyms included. Species do not include records of infraspecific taxa. Blue line denotes Manual flowering time.