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Lactuca
Family: Asteraceae
Lactuca image
Patrick Alexander  
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John L. Strother in Flora of North America (vol. 19, 20 and 21)
Annuals or biennials, 15-450+ cm; taprooted. Stems usually 1, usually erect, branched distally or throughout, glabrous or hairy (sometimes hispid to setose). Leaves basal and cauline or mostly cauline (at flowering); sessile or petiolate; blades orbiculate, ovate, oblong, or lanceolate to oblanceolate, linear, or filiform, margins entire or denticulate to pinnately lobed (faces glabrous or hairy, often ± setose). Heads borne singly or in corymbiform to paniculiform arrays. Peduncles not inflated distally, sometimes bracteate. Calyculi of 3-10+, deltate to lanceolate bractlets in 2-3 series (sometimes intergrading with phyllaries). Involucres campanulate to cylindric, 2-5[-8+] mm diam. Phyllaries 5-13+ in ± 2 series (erect or reflexed in fruit), lanceolate to linear, usually subequal to equal, margins sometimes scarious, apices obtuse to acute. Receptacles flat to convex, pitted, glabrous, epaleate. Florets 6-50+; corollas yellow, bluish, or whitish. Cypselae reddish brown, tan, whitish, or purplish to blackish, bodies compressed to flattened, elliptic to oblong, beaks stout (0.1-1 mm, gradually or weakly set off from bodies) or filiform (2-6 mm, sharply set off from bodies), ribs 1-9 on each face, faces often transversely rugulose, usually glabrous; pappi persistent (borne on discs at tips of cypselae or beaks), obscurely double (spp. 1-2), each a minute, erose corona 0.05-0.2 mm subtending 40-80+, white or fuscous, ± equal, barbellate to barbellulate bristles in 1-2 series, or simple (spp. 3-10) of 80-120+, white, ± equal, barbellulate to nearly smooth bristles in 2-3+ series. x = 9. The common head and leaf lettuces of home gardens and commerce are derived from Lactuca sativa.

Vascular plants of NE US and adjacent Canada
Fls all ligulate and perfect, yellow, blue, or white, the cor- tube generally more than half as long as the ligule; invol cylindric, often broadened at the base in fr, generally imbricate, occasionally merely calyculate; achenes compressed, winged or strongly nerved marginally, with 1 or several lesser nerves in each face, beaked or sometimes beakless, but in any case expanded at the summit where the pappus is attached; pappus of 2 rows of usually equal capillary bristles, none markedly coarser than the others; lactiferous herbs with alternate, entire to pinnatifid lvs and usually numerous heads with relatively few fls (5-56 per head in our spp.), the infl mostly paniculiform. (Mulgedium, Mycelis) 50, Eurasia, Afr., and N. Amer.

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
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Species within inventory project:
Lactuca alpina
Image of Lactuca alpina
Lactuca azurea
Images
not available
Lactuca biennis
Image of Lactuca biennis
Lactuca brachyrrhyncha
Image of Lactuca brachyrrhyncha
Lactuca canadensis
Image of Lactuca canadensis
Lactuca crambifolia
Images
not available
Lactuca elongata
Image of Lactuca elongata
Lactuca floridana
Image of Lactuca floridana
Lactuca glandulifera
Image of Lactuca glandulifera
Lactuca graminifolia
Image of Lactuca graminifolia
Lactuca hirsuta
Image of Lactuca hirsuta
Lactuca indica
Images
not available
Lactuca integrifolia
Image of Lactuca integrifolia
Lactuca intybacea
Image of Lactuca intybacea
Lactuca jamaicensis
Image of Lactuca jamaicensis
Lactuca leucophaea
Image of Lactuca leucophaea
Lactuca ludoviciana
Image of Lactuca ludoviciana
Lactuca orientalis
Images
not available
Lactuca perennis
Image of Lactuca perennis
Lactuca plumieri
Image of Lactuca plumieri
Lactuca quercina
Image of Lactuca quercina
Lactuca saligna
Image of Lactuca saligna
Lactuca sativa
Image of Lactuca sativa
Lactuca serriola
Image of Lactuca serriola
Lactuca sibirica
Image of Lactuca sibirica
Lactuca stolonifera
Image of Lactuca stolonifera
Lactuca tatarica
Image of Lactuca tatarica
Lactuca terrae-novae
Image of Lactuca terrae-novae
Lactuca viminea
Image of Lactuca viminea
Lactuca virosa
Image of Lactuca virosa
Lactuca × morssii
Image of Lactuca × morssii
Mulgedium oblongifolium
Image of Mulgedium oblongifolium
Mulgedium pulchellum
Image of Mulgedium pulchellum
Mycelis muralis
Image of Mycelis muralis
The National Science Foundation
Developments of SEINet, Symbiota, and associated specimen databases have been supported by National Science Foundation Grants (DBI 9983132, BRC 0237418, DBI 0743827, DBI 0847966)