|University of California, Berkeley|
|Directory News Site Map Home|
Key to families | Table of families and genera
Specimen numbers are hyperlinked to records in the Consortium of California Herbaria data view where possible. Taxa are hyperlinked to entries in the Jepson Interchange via the "[Online Interchange]" link.
Annual, perennial herb [to shrub], weak, stinging hairs 0 or few to many; monoecious or dioecious. Stem: branched or not, erect, spreading, or decumbent. Leaf: opposite, lanceolate to cordate, toothed, prominently 3–5-veined from base; crystals round to elongate. Inflorescence: head-, raceme-, or panicle-like. Staminate flower: sepals 4, ± free, green, sharp-bristly; stamens 4. Pistillate flower: sepals 4, ± free, outer 2 < inner 2. Fruit: lenticular to deltate, enclosed by 2 inner sepals.
± 45 species: especially temperate. (Latin: to burn, from stinging hairs)
Unabridged references: [Woodland 1982 Syst Bot 7:282–290]
1. Annual 1–6(8) dm; leaf blade 18–40(90) mm; inflorescence generally ± head- or spike-like, often < petiole, of staminate and pistillate flowers; fruit deltate ..... U. urens
1' Perennial herb 5–30 dm; leaf blade 60–200 mm; inflorescence raceme- or panicle-like, generally > petiole, of staminate or pistillate flowers; fruit ovate ..... U. dioica
2. Non-stinging hairs on stem, leaf 0 to ± dense, occasionally > 1 mm, those on abaxial veins appressed; stem green ..... subsp. gracilis
2' Non-stinging hairs on stem, leaf dense, < 1 mm, those on abaxial veins erect; stem gray-green ..... subsp. holosericea
Citation for the whole project: Jepson Flora Project (eds.) [year] Jepson eFlora, http://ucjeps.berkeley.edu/IJM.html [accessed on month, day, year]
Citation for an individual treatment: [Author of taxon treatment] [year]. [Taxon name] in Jepson Flora Project (eds.) Jepson eFlora, [URL for treatment]. Accessed on [month, day, year].
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.