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 August 27, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on August 27, 2016.


Alnus rubra
click for enlargement
© 2009 Neal Kramer
Alnus rubra
click for enlargement
© 2008 California Academy of Sciences
Alnus rubra
click for enlargement
© 2007 Neal Kramer
Alnus rubra
click for enlargement
© 2007 Neal Kramer
Alnus rubra
click for enlargement
© 2008 California Academy of Sciences
Alnus rubra
click for enlargement
© 2007 California Academy of Sciences

More photos of Alnus rubra in CalPhotos


Geographic subdivisions for Alnus rubra:
NCo, w KR, NCoRO, CCo, SnFrB;
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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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).

View elevation by latitude chart
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.