Jepson Flora Project: Jepson Interchange    

 
link to manual TREATMENT FROM THE JEPSON MANUAL (1993) previous taxon | next taxon
Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California
For up-to-date information about California vascular plants, visit the Jepson eFlora.

ASTERACEAE

SUNFLOWER FAMILY

David J. Keil, Family Editor and author, except as specified

Annual to tree
Leaves basal or cauline, alternate to whorled, simple to compound
Inflorescence: 1° inflorescence a head, each resembling a flower, 1–many, generally arrayed in cymes, generally subtended by ± calyx-like involucre; flowers 1–many per head
Flowers bisexual, unisexual, or sterile, ± small, of several types; calyx 0 or modified into pappus of bristles, scales, or awns, which is generally persistent in fruit; corolla radial or bilateral (rarely 0), lobes generally (0)4–5; stamens 4–5, anthers generally fused into cylinder around style, often appendaged at tips, bases, or both, filaments generally free, generally attached to corolla near throat; pistil 1, ovary inferior, 1-chambered, 1-seeded, style 1, branches 2, generally hair-tufted at tip, stigmas 2, generally on inside of style branches
Fruit: achene, cylindric to ovoid, generally deciduous with pappus attached
Genera in family: ± 1300 genera, 21,000 species (largest family of dicots): worldwide. Largest family in CA. Also see tribal key to CA genera: Strother 1997 Madroño 44(1):1–28. See glossary p. 25 for illustrations of general family characteristics.

LACTUCA

LETTUCE

G. Ledyard Stebbins

Annual to perennial herb; sap milky
Stems erect, 0.5–1.5+ m
Leaves basal and cauline, alternate, entire to pinnately lobed
Inflorescence: heads ligulate, many, in panicles; involucre cylindric; phyllaries in 2–several series; receptacle naked
Flowers few–many; ligules yellow or cream to blue, readily withering
Fruit flattened, short- or long-beaked; pappus of many bristles, falling separately
Species in genus: ± 100 species: ± worldwide temp
Etymology: (Latin: milky)

Introduced

L. canadensis L.

Mostly biennial from taproot, 0.5–2.5 m
Leaves many, elliptic in outline, lobed; lobes linear, curved, mostly entire; bases acute, clasping
Inflorescence open, heads in flower 5–10 mm wide; involucre in fruit 10–15 mm
Flowers 13–25; corolla pale yellow
Fruit 5–6 mm, elliptic, blackish, rough, with 1 rib on each face, unwinged; beak pale, ± = body; pappus 5–7 mm, white
Chromosomes: 2n=34
Ecology: Forests and waste places
Elevation: < 1050 m.
Bioregional distribution: Klamath Ranges, n Sierra Nevada
Distribution outside California: native to e N.America

previous taxon | next taxon
bioregional map for LACTUCA%20canadensis 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 Lactuca canadensis
Retrieve dichotomous key for Lactuca
Retrieve multiple-entry key (MEKA) for Lactuca
Overlay Consortium of California Herbaria specimen data by county on this map
Show other taxa with the same California distribution | Read about bioregions | Get lists of plants in a bioregion
Return to the Jepson Interchange main page
Return to treatment index page
Glossary
    FEEDBACK
  • This page is no longer being maintained.


University & Jepson Herbaria Home Page |
General Information | University Herbarium | Jepson Herbarium |
Visiting the Herbaria | On-line Resources | Research |
Education | Related Sites
Copyright © by the Regents of the University of California