Directory       News       Site Map       Home
    Jepson eFlora: Taxon page
Key to families | Table of families and genera

Previous taxon Indexes to all 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 |
Previous taxon


Robert Lee Allen

Tree, generally monoecious, wind-pollinated; hairs many-branched. Stem: bark peeling in scaly plates, leaving ± smooth areas of various colors, in age dark, thick, fissured; twig hairs dense. Leaf: simple, alternate, deciduous; lobes, veins generally 3,5(7), palmate; stipules generally leaf-like, free or fused around stem, shed by leaf maturity or not; petiole at base dilated, hollow, ± covering bud; blade hairs dense, ± 0 in age. Inflorescence: heads 1–7, ± evenly spaced on axis, spheric, many-flowered, sessile or on pendent peduncles, generally unisexual; staminate breaking apart in age; pistillate persistent; bracts subtending heads, flowers. Flower: unisexual; calyx cup-shaped, sepals (0)3–6(8), free or united basally. Staminate flower: petals 3–6, minute or vestigial, fleshy or scale-like; stamens 3–6(8), alternate petals, anthers subsessile, axis above anther expanded, disk-like, ± peltate; carpels vestigial or 0. Pistillate flower: petals 3–6, minute, or generally 0; staminodes often 3–4; carpels (3)5–9, free, ovary of each superior, 1-chambered, generally 1-ovuled, with 1 ± linear style. Fruit: achenes in spheric head, small, each with hairs from base, shorter hairs up the side; style persistent, beak-like, or deciduous.
1 genus, ± 8 species: northern temperate; some cultivated for ornamental, shade; wood generally of limited commercial value. [Feng et al. 2005 Syst Bot 30:786–799] —Scientific Editor: Thomas J. Rosatti.
Unabridged genera in family: 1 genus, ± 8 species: northern temperate; some cultivated for ornamental, shade; wood generally of limited commercial value, although long ago used for buttons, the trees then called buttonwood.
Unabridged note: Leaves and twigs with many-branched hairs, each comprising a single multicellular central axis with unicellular lateral, generally whorled rays.

(Greek: probably broad, for leaves) Fruit length excludes style.

Key to Platanus

P. racemosa Nutt. WESTERN SYCAMORE
Stem: 10–35 m, often leaning; base < 1(2+) m wide; outer bark light gray, tan, inner paler. Leaf: stipules 2–3 cm, generally persistent after maturity; petiole 3–8 cm; blade ± 10–25 cm, ± round, glabrous to ± hairy adaxially, tomentose abaxially. Staminate flower: sepals 0; petals free. Pistillate flower: sepals free; style red-tipped, stigma maroon, glabrous. Fruit: head 2–3 cm, ± sessile; achene 7–10 mm, top truncate or tapered, basal hairs ± 2/3 fruit, persistent on fruit head; style generally persistent.
2n=42. Common. Streamsides, canyons, arroyos; < 2000 m. Cascade Range Foothills, c&s Sierra Nevada Foothills, Tehachapi Mountain Area, Great Central Valley, Central Western California, Southwestern California, Mojave Desert (Mojave River, n of Victorville), nw Sonoran Desert; Baja California. Hybridizes with Platanus ×hispanica Muenchh; some plants in eastern Peninsular Ranges with leaves similar to Platanus wrightii S. Watson of Arizona, New Mexico, Mexico, but with fruit of Platanus racemosa. Feb–Apr [Online Interchange]
Unabridged note: Some plants in eastern Peninsular Ranges at northwestern edge of Sonoran Desert (e.g., Snow, Chino, Andreas canyons of San Jacinto Mountains) appear intermediate to Platanus wrightii S. Watson, Arizona sycamore, of Arizona, New Mexico, Mexico [Platanus racemosa var. wrightii (S. Watson) L. Benson]. These plants generally have leaves hairy but not tomentose abaxially but fruit identical to Platanus racemosa (fruit of Platanus wrightii 5–8 mm, top truncate or abruptly tapered, basal hairs generally 2/3 to = fruit length, style generally deciduous). New growth often killed by sycamore anthracnose fungus, causing angular branching; leaves eaten by sycamore lace bug; bark mined by larvae of sycamore borer moth causing it to roughen, crumble. Leaves may be re-attached by pushing hollow petiole bases back over bud.

Previous taxon: Platanus X hispanica
Next taxon: Plumbaginaceae


Name search

Citation for the whole project: Jepson Flora Project (eds.) 2013. Jepson eFlora,, accessed on Nov 27 2015
Citation for this treatment: [Author of taxon treatment] 2013. Platanus, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on Nov 27 2015

Copyright © 2014 Regents of the University of California
We encourage links to these pages, but the content may not be downloaded for reposting, repackaging, redistributing, or sale in any form, without written permission from The Jepson Herbarium.

Geographic subdivisions indicated for the distribution of Platanus racemosa 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.
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).

View elevation by latitude chart
Data provided by the participants of the Consortium of California Herbaria.
View all CCH records


CCH collections by month

Duplicates counted once; synonyms included.
Species do not include records of infraspecific taxa.
Blue line denotes eFlora flowering time.