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Populus trichocarpa
BLACK COTTONWOOD

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 trichocarpa Hook.
NATIVE
Habit: Tree < 30 m; crown wide. Stem: twigs brown, in age gray; winter buds finely ciliate, very resinous, fragrant when opening. Leaf: petiole 1/3--1/2 blade, abaxially round, adaxially channeled; blade 3--7 cm, narrowly to widely ovate (sometimes lanceolate on suckers, stressed plants), adaxially green, abaxially glaucous, often stained with brown resin, base round to cordate, tip acute to tapered, margin finely scalloped. Chromosomes: 2n=38.
Ecology: Scattered. Alluvial bottomland, streamsides; Elevation: 5--3050 m. Bioregional Distribution: CA-FP, GB; Distribution Outside California: to Alaska, northern Rocky Mountains, Utah, northern Baja California. Flowering Time: Feb--Apr
Synonyms: Populus balsamifera L. subsp. trichocarpa (Hook.) Brayshaw
Unabridged Note: Treatment as separate sp. supported by molecular data (Cervara et al.). Hybrids with Populus fremontii (Populus ×parryi) reported for California. See note under Populus angustifolia.
eFlora Treatment Author: John O. Sawyer, Jr.
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Citation for this treatment: John O. Sawyer, Jr. 2016. Populus trichocarpa, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=39463, accessed on May 29, 2016.

Citation for the whole project: Jepson Flora Project (eds.) 2016. Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html, accessed on May 29, 2016.


Populus trichocarpa
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© 2012 Steve Matson
Populus trichocarpa
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© 2012 Steve Matson
Populus trichocarpa
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© 2007 Neal Kramer
Populus trichocarpa
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© 2012 Steve Matson
Populus trichocarpa
click for enlargement
© 2012 Steve Matson
Populus trichocarpa
click for enlargement
© 2012 Steve Matson

More photos of Populus trichocarpa in CalPhotos


Geographic subdivisions for Populus trichocarpa:
CA-FP, GB;
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.
READ ABOUT YELLOW FLAGS
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.