Difference between revisions of "Lactuca sativa"
Sp. Pl. 2: 795. 1753.
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Revision as of 18:36, 24 September 2019
Annuals or biennials, (15–)30–70(–100+) cm. Leaves on proximal 1/2–3/4 of each stem; blades of undivided cauline leaves ovate to orbiculate, margins entire or denticulate, seldom prickly, midribs rarely prickly-setose. Heads usually in corymbiform, sometimes in paniculiform, arrays. Involucres 8–13+ mm. Phyllaries usually erect in fruit. Florets 7–15(–30+); corollas yellow (sometimes streaked with violet), usually deliquescent. Cypselae: bodies pale grayish to whitish or tan, ± flattened, obovate, 3–4 mm, beaks ± filiform, 3–5 mm, faces 5–9-nerved; pappi white, 3.5–4+ mm. 2n = 18.
Phenology: Flowering mostly Jul–Sep.
Habitat: Disturbed sites, abandoned plantings
Elevation: 10–1000 m
Distribution
Ont., Ala., Calif., Conn., Del., D.C., Idaho, Ill., Ind., Maine, Mass., Mich., Mo., N.H., N.J., N.Mex., N.Y., N.C., N.Dak., Ohio, Okla., Oreg., Pa., R.I., Vt., Wash., W.Va., Eurasia, introduced also in Mexico, introduced or ephemeral nearly worldwide.
Discussion
Selected References
None.