Jepson Flora Project: Jepson Interchange    

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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
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Shrub, tree, generally dioecious (rarely monoecious)
Stem: trunk < 40 m; wood soft; bark smooth, bitter; buds scaly
Leaves simple, alternate, deciduous; stipules generally deciduous, often large
Inflorescence: catkin, generally appearing before leaves; each flower subtended by disk or 1–2 nectary glands and 1 bract
Flower: perianth 0
Staminate flower: stamens 1–many
Pistillate flower: pistil 1, ovary superior, chamber 1, stigma lobes 2–4
Seeds many; hairs fine, white, cottony
Fruit: capsule; valves 2–4
Genera in family: 2 genera, 340 species: generally temp (except Australia, Malay Archipelago) moist places; many cultivated. Hybridization common; identification often difficult. Family description, key to genera by John O. Sawyer, Jr.



John O. Sawyer, Jr.

Stem: trunk < 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
Leaves generally glabrous (juvenile leaves may differ from adult leaves); blade 3–11 cm, elliptic to triangular, veins pinnate or subpalmate, tip generally elongate
Inflorescence: catkin pendent, 3–8 cm; bract cut into narrow segments; flowers sessile, on a cup- or saucer-like disk
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: n hemisphere
Etymology: (Latin: name for plants of this genus)


P. tremuloides Michx.


Stem: crown slender; trunk < 15 m, highly clonal; twigs greenish white, glabrous; winter buds shiny
Leaf: petiole 2/3 to = blade length, laterally compressed; blade 2–4(7) cm, widely ovate or wider, base rounded to cordate, tip tapered, margin finely scalloped, surfaces glabrous, upper green, lower glaucous
Chromosomes: 2n=38
Ecology: Streamsides, moist openings and slopes in montane and subalpine forests, woodlands, sagebrush steppe
Elevation: 1800–3000 m.
Bioregional distribution: Klamath Ranges, High North Coast Ranges, Cascade Range, High Sierra Nevada, San Bernardino Mountains, Great Basin Floristic Province
Distribution outside California: to Alaska, e N.America, Mexico
Flowering time: Apr–Jun
Horticultural information: IRR, SUN, DRN: 1, 2, 3, 4, 5, 6, 7, 14, 15, 16, 17, 18, 19, 20, 21; INV; also STBL.

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bioregional map for POPULUS%20tremuloides being generated
YOU CAN HELP US make sure that our distributional information is correct and current. If you know that a plant occurs in a wild, reproducing state in a Jepson bioregion NOT highlighted on the map, please contact us with that information. Please realize that we cannot incorporate range extensions without access to a voucher specimen, which should (ultimately) be deposited in an herbarium. You can send the pressed, dried collection (with complete locality information indicated) to us (e-mail us for details) or refer us to an accessioned herbarium specimen. Non-occurrence of a plant in an indicated area is difficult to document, but we will especially value your input on those types of possible errors (see automatic conversion of distribution data to maps).

Retrieve Jepson Interchange Index to Plant Names entry for Populus tremuloides
Retrieve dichotomous key for Populus
Overlay Consortium of California Herbaria specimen data by county on this map
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