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Lactuca serriola

Higher Taxonomy
Family: Asteraceae (Compositae)View DescriptionDichotomous Key

Habit: Annual to tree. Leaf: basal and/or cauline, alternate, opposite, rarely whorled, simple to 2+ × compound. Inflorescence: 1° inflorescence a head, resembling a flower, of several types (see below), 1--many in generally +- cyme-like cluster; each head generally with +- calyx-like involucre of 1--many series of phyllaries (involucre bracts); receptacle of head flat to conic or columnar, paleate (bearing paleae = receptacle bracts) or epaleate; flowers 1--many per head. Flower: bisexual, unisexual, or sterile, +- small, of several types (see below); calyx 0 or modified into +- persistent pappus of bristles, scales, and/or awns; corolla radial or bilateral (0), lobes generally (0)3--5; stamens 4--5, filaments generally free, generally fused to corolla at tube/throat junction, anthers generally fused into cylinder around style, anther base generally rounded or cordate (deeply sagittate or with tail-like appendages), tip (= flattened appendage) generally projecting beyond pollen sac; pistil 1, 2-carpeled, ovary inferior, 1-chambered, 1-seeded, placenta basal, style 1, tip generally +- 2-branched (except in some staminate disk flowers), branch tips truncate or generally bearing +- brush-like appendages; stigmas 2, generally on adaxial faces of style branches. Fruit: achene (also called a cypsela) (drupe in Chrysanthemoides), cylindric to ovoid, sometimes compressed, generally deciduous with pappus attached.
Genera In Family: +- 1500 genera, 23000 species: worldwide, many habitats. Note: Flower and head types differ in form and sexual condition. A disk flower has a generally radial corolla, with a cylindric tube, expanded throat, and generally 5 lobes. Disk flowers are generally bisexual and fertile but occasionally staminate with reduced ovaries. Discoid heads comprise only disk flowers. A radiant head is a variant of a discoid head, with peripheral disk flower corollas expanded, often bilateral. A ray flower corolla is bilateral, generally with a slender tube and flattened petal-like ray (single lip composed of generally 3 lobes). Ray flowers are generally pistillate or sterile (occasionally lacking styles). Radiate heads have peripheral ray flowers and central disk flowers. Disciform heads superficially resemble discoid heads, with pistillate or sterile flowers that lack rays, together with or separate from disk flowers. A ligulate flower is bisexual, with a bilateral, generally ephemeral corolla and 5-lobed ligule. Liguliflorous heads comprise only ligulate flowers. See glossary p. 31 for illustrations of family characteristics. Echinops sphaerocephalus L., Gaillardia aristata Pursh, Gaillardia pulchella Foug., Hymenothrix loomisii S.F. Blake, Tagetes erecta L., Thelesperma megapotamicum (Spreng.) Kuntze are waifs. Melampodium perfoliatum Kunth, historic urban waif. Ageratum conyzoides L., Guizotia abyssinica (L. f.) Cass., Santolina chamaecyparisus L., orth. var. are rare or uncommon escapes from cultivation. Dyssodia papposa, Ismelia carinata (Schousb.) Sch. Bip. [Chrysanthemum carinatum Schousb.], Mantisalca salmantica (L.) Briq. & Cavill. are historical or extirpated waifs in California. Inula helenium L. not documented in California. Taxa of Aster in TJM (1993) treated here in Almutaster, Eucephalus, Eurybia, Ionactis, Oreostemma, Sericocarpus, Symphyotrichum; Chamomilla in Matricaria; Bahia in Hymenothrix; Cnicus in Centaurea; Conyza in Erigeron and Laennecia; Dugaldia in Hymenoxys; Erechtites in Senecio; Hymenoclea in Ambrosia; Lembertia in Monolopia; Osteospermum ecklonis in Dimorphotheca; Picris echioides in Helminthotheca; Prionopsis in Grindelia; Raillardiopsis in Anisocarpus and Carlquistia; Schkuhria multiflora in Picradeniopsis; Trimorpha in Erigeron; Venidium in Arctotis; Whitneya in Arnica. Amauriopsis in TJM2 (2012) treated here in Hymenothrix; Arida in Leucosyris; Bahia in Picradeniopsis.
Unabridged Note: Largest family of vascular plants in California and of eudicots globally.
eFlora Treatment Author: David J. Keil, except as noted
Scientific Editor: David J. Keil, Bruce G. Baldwin.
Genus: LactucaView DescriptionDichotomous Key

Common Name: LETTUCE
Habit: Annual to perennial herb; sap milky. Stem: decumbent to erect. Leaf: basal and cauline, alternate, entire to pinnately lobed. Inflorescence: heads liguliflorous, in panicle-like or flat-topped clusters; involucre +- cylindric; phyllaries in 2--several series; receptacle flat or rounded, epaleate. Flower: 6--50+; ligules yellow or cream to blue, readily withering. Fruit: flattened, short- or long-beaked; pappus of 80--120+ bristles, falling separately.
Species In Genus: +- 100 species: +- worldwide temperate. Etymology: (Latin: milky) Note: Lactuca sativa L. (garden lettuce) occasionally escapes from cultivation but does not persist.
eFlora Treatment Author: David J. Keil & G. Ledyard Stebbins
Reference: Strother 2006 FNANM 19:258--263

Lactuca serriola L.
Habit: Annual from taproot. Stem: 0.5--3 m, erect, prickly-bristly. Leaf: few to many, oblanceolate to oblong-elliptic or obovate, margin prickly-bristly, unlobed or coarsely lobed; base sagittate-clasping; abaxial veins (especially midvein) prickly-bristly. Inflorescence: heads generally many, in open, panicle-like clusters, branches often widely spreading; open heads 4--6 mm diam; involucre in fruit 10--12 mm. Flower: 14--20; corolla pale yellow. Fruit: body 2.5--3.5 mm, light to dark brown, rough-hairy, unwinged, faces 5--7-ribbed, beak 2.5--4 mm, thread-like; pappus 3.5--5 mm, white. Chromosomes: 2n=18.
Ecology: Abundant. Disturbed places; Elevation: < 2700 m. Bioregional Distribution: CA; Distribution Outside California: North America; native to Europe. Flowering Time: May--Oct
Synonyms: Lactuca serriola var. integra Gren. & Godr.;
eFlora Treatment Author: David J. Keil & G. Ledyard Stebbins
Reference: Strother 2006 FNANM 19:258--263
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botanical illustration including Lactuca serriola


Citation for this treatment: David J. Keil & G. Ledyard Stebbins 2012, Lactuca serriola, in Jepson Flora Project (eds.) Jepson eFlora,, accessed on January 23, 2018.

Citation for the whole project: Jepson Flora Project (eds.) 2018, Jepson eFlora,, accessed on January 23, 2018.

Lactuca serriola
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© 2009 Barry Breckling
Lactuca serriola
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© 2010 Barry Breckling
Lactuca serriola
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© 2009 Barry Breckling
Lactuca serriola
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© 2008 Keir Morse
Lactuca serriola
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© 2012 James M. Andre
Lactuca serriola
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© 2014 Neal Kramer

More photos of Lactuca serriola in CalPhotos

Geographic subdivisions for Lactuca serriola:
Markers link to CCH specimen records. Yellow markers indicate records that may provide evidence for eFlora range revision or may have georeferencing or identification issues. Purple markers indicate specimens collected from a garden, greenhouse, or other non-wild location.
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).

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Data provided by the participants of the Consortium of California Herbaria.
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CCH collections by month

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