Jepson eFlora: Taxon page
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Populus tremuloides
QUAKING ASPEN

Higher Taxonomy
Family: SalicaceaeView DescriptionDichotomous Key

Common Name: WILLOW FAMILY
Habit: Shrub, tree; dioecious (monoecious). Stem: trunk < 40 m; wood soft; bark smooth, bitter; buds scaly. Leaf: simple, alternate, deciduous; stipules generally present, deciduous or not, often large. Inflorescence: catkin [or various, or flowers 1]; each flower subtended by 1 bract. Flower: perianth modified into non-nectariferous, cup- or saucer-shaped structure or reduced to adaxial nectary (rarely also with abaxial nectary, then free or fused into shallow cup). Staminate Flower: stamens 2--many. Pistillate Flower: pistil 1, ovary superior to 1/2-inferior, chambers generally 2--4, placentas parietal, stigma lobes 2--4. Fruit: berry, drupe, or 2--4-valved capsule. Seed: often with basal tuft of hairs.
Genera In Family: 58 genera, 1210 species: widespread in tropics, northern temperate, arctic. Note: Now including many genera (e.g., Flacourtia, Idesia, Xylosma) formerly in Flacourtiaceae, at least in part because of presence on leaf margins in both families of salicoid teeth (vein extending to tooth tip). In California (and generally outside California), Populus pollinated by wind, Salix by insects, wind. Hybrids common; identification often difficult.
eFlora Treatment Author: John O. Sawyer, Jr., except as noted
Scientific Editor: Thomas J. Rosatti.
Genus: PopulusView DescriptionDichotomous Key

Common Name: COTTONWOOD
Habit: Tree. Stem: < 40 m; young bark smooth, pale yellow-green to gray; older bark furrowed, brown to gray; twigs with swellings below leaf scars; winter bud generally resinous, scales > 3. Leaf: juvenile, adult, late-season leaves may differ in size, shape, hairiness; generally glabrous; blade 3--11 cm, elliptic to deltate, veins pinnate or +- palmate, tip generally elongate. Inflorescence: catkin pendent, 3--8 cm; bract cut into narrow segments; flowers sessile; nectary a cup- or saucer-like disk. Flower: perianth modified into non-nectariferous, cup- or saucer-shaped structure. Staminate Flower: stamens 8--60. Pistillate Flower: style short, stigmas 2--3(4), large, scalloped to 2-lobed. Fruit: spheric to conic; valves 2--3(4), 3--12 mm.
Species In Genus: 40 species: northern hemisphere. Etymology: (Latin: name for plants of this genus)

Populus tremuloides Michx.
NATIVE
Habit: Tree < 15 m; crown slender; highly clonal. Stem: twigs green-white, glabrous; winter buds shiny. Leaf: petiole 2/3 to = blade, laterally compressed; blade 2--4(7) cm, widely ovate to +- round, glabrous, adaxially green, abaxially glaucous, base rounded to cordate, tip tapered, margin finely crenate to serrate. Chromosomes: 2n=38.
Ecology: Streamsides, moist openings, slopes in montane, subalpine forest, woodland, sagebrush steppe; Elevation: 900--3150 m. Bioregional Distribution: KR, NCoRH, CaR, SNH, SnBr, GB; Distribution Outside California: to Alaska, eastern North America, Mexico. Flowering Time: Apr--Jun
eFlora Treatment Author: John O. Sawyer, Jr.
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Citation for this treatment: John O. Sawyer, Jr. 2016. Populus tremuloides, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=39509, accessed on April 30, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on April 30, 2016.


Populus tremuloides
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© 2011 California Academy of Sciences
Populus tremuloides
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© 2014 California Academy of Sciences
Populus tremuloides
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© 2009 California Academy of Sciences
Populus tremuloides
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© 2015 Barry Breckling
Populus tremuloides
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© 2014 California Academy of Sciences
Populus tremuloides
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© 2014 California Academy of Sciences

More photos of Populus tremuloides in CalPhotos


Geographic subdivisions for Populus tremuloides:
KR, NCoRH, CaR, SNH, SnBr, GB;
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.