Jepson eFlora: Taxon page
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Alnus rubra
RED ALDER

Higher Taxonomy
Family: BetulaceaeView DescriptionDichotomous Key

Common Name: BIRCH FAMILY
Habit: 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.
Genera In Family: 6 genera, 155 species: generally northern hemisphere; some cultivated.
eFlora Treatment Author: John O. Sawyer, Jr.
Scientific Editor: Thomas J. Rosatti.
Genus: AlnusView DescriptionDichotomous Key

Common Name: 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.
Species In Genus: +- 25 species: northern hemisphere, South America. Etymology: (Latin: alder) Note: Root nodules contain nitrogen-fixing bacteria; wood used for interior finishing, to smoke fish, meats.

Alnus rubra Bong.
NATIVE
Habit: Tree. Stem: trunk < 25 m. Leaf: blade thick, base rounded to tapered, tip acute, margin tightly rolled under, adaxially gray-green, midrib, major veins indented, abaxially +- gray-green, rusty-hairy, or with rusty, sessile glands.
Ecology: Wet places, especially after logging; Elevation: < 1000 m. Bioregional Distribution: NCo, w KR, NCoRO, CCo, SnFrB; Distribution Outside California: to southern Alaska, Idaho. Flowering Time: Feb--Mar
Synonyms: Alnus oregona Nutt.
eFlora Treatment Author: John O. Sawyer, Jr.
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botanical illustration including Alnus rubra

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Citation for this treatment: John O. Sawyer, Jr. 2016. Alnus rubra, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=12723, accessed on February 10, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on February 10, 2016.


Alnus rubra
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© 2002 Tony Morosco
Alnus rubra
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© 2008 California Academy of Sciences
Alnus rubra
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© 2008 Keir Morse
Alnus rubra
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© 2007 Neal Kramer
Alnus rubra
click for enlargement
© 2007 California Academy of Sciences
Alnus rubra
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© 2009 Neal Kramer

More photos of Alnus rubra in CalPhotos


Geographic subdivisions for Alnus rubra:
NCo, w KR, NCoRO, CCo, SnFrB;
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.
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map of distribution 1
(Note: any qualifiers in the taxon distribution description, such as 'northern', 'southern', 'adjacent' etc., are not reflected in the map above, and in some cases indication of a taxon in a subdivision is based on a single collection or author-verified occurence).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.