Jepson eFlora: Taxon page
Key to families | Table of families and genera
Previous taxon Index to accepted names and synonyms:
| A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z |
Next taxon
Populus
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.

Populus
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)
eFlora Treatment Author: John O. Sawyer, Jr.
Jepson Online Interchange
Key to Populus

Previous taxon: Salicaceae
Next taxon: Populus alba

Name Search

Contact/Feedback

Citation for this treatment: John O. Sawyer, Jr. 2016. Populus, in Jepson Flora Project (eds.) Jepson eFlora, http://ucjeps.berkeley.edu/cgi-bin/get_IJM.pl?tid=9886, accessed on July 30, 2016.

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


Populus tremuloides
click for enlargement
© 2014 California Academy of Sciences
Populus trichocarpa
click for enlargement
© 2012 Steve Matson
Populus tremuloides
click for enlargement
© 2004 California Academy of Sciences
Populus tremuloides
click for enlargement
© 1999 California Academy of Sciences
Populus tremuloides
click for enlargement
© 2016 Keir Morse
Populus fremontii subsp. fremontii
click for enlargement
© 2009 Keir Morse

More photos of Populus in CalPhotos