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Vascular Plants of California
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Alnus incana subsp. tenuifolia
MOUNTAIN 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 incana (L.) Moench subsp. tenuifolia (Nutt.) Breitung
NATIVE
Habit: Shrub. Stem: trunks < 9 m. Leaf: blade thick, base rounded to subcordate, tip rounded to acute, margin generally +- flat, adaxially dark green, dull, midrib, major veins generally indented, abaxially yellow-green.
Ecology: Wet places; Elevation: 1200--2400 m. Bioregional Distribution: KR, NCoRH, CaRH, SNH; Distribution Outside California: to Alaska, western Canada, Wyoming, New Mexico. Flowering Time: Apr--Jun Note: 2 other subspecies in Alaska, Canada, Europe.
Synonyms: Alnus tenuifolia Nutt.
Jepson eFlora Author: John O. Sawyer, Jr.
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Citation for this treatment: John O. Sawyer, Jr. 2012, Alnus incana subsp. tenuifolia, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/eflora/eflora_display.php?tid=49084, accessed on December 08, 2019.

Citation for the whole project: Jepson Flora Project (eds.) 2019, Jepson eFlora, http://ucjeps.berkeley.edu/eflora/, accessed on December 08, 2019.

Alnus incana subsp. tenuifolia
click for enlargement
© 2012 Julie Kierstead Nelson
Alnus incana subsp. tenuifolia
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© 2017 Julie Kierstead Nelson
Alnus incana subsp. tenuifolia
click for enlargement
© 2012 Julie Kierstead Nelson
Alnus incana subsp. tenuifolia
click for enlargement
© 1999 California Academy of Sciences
Alnus incana subsp. tenuifolia
click for enlargement
© 2012 Julie Kierstead Nelson
Alnus incana subsp. tenuifolia
click for enlargement
© 2012 Julie Kierstead Nelson

More photos of Alnus incana subsp. tenuifolia in CalPhotos



Geographic subdivisions for Alnus incana subsp. tenuifolia:
KR, NCoRH, CaRH, SNH
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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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All markers link to CCH specimen records. The original determination is shown in the popup window.
Blue markers indicate specimens that map to one of the expected Jepson geographic subdivisions (see left map). Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues.
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CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa, if there are more than 1 infraspecific taxon in CA.
Blue line denotes eFlora flowering time.