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Lactuca
See list of 5 species in this genusLactuca floridana (L.) Gaertn. was attributed to New England based on a collection from Eastham, MA ( Collins 1774 NEBC!). The specimen is L. biennis with apically pale pappus bristles (the basal half of the pappus bristles, the portion concealed by the involucral bracts, is light brown; L. floridana would have white pappus bristles). Lactuca saligna L. was reported from MA and ME by Strother (2006d), but specimens are unknown. Reference: Strother (2006d).
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1a. Basal leaf blades of commonly cultivated forms ovate to orbicular, 12–25 cm wide; plants rare escapes from cultivation
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1b. Basal leaf blades linear to ovate, 0.6–12 cm wide; plants native or introduced, but not generally cultivated
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2a. Cypsela apically beakless or with a short, stout beak 0.1–0.5 mm long [Fig. 429], the body compressed but not flat; pappus light brown to light olive-brown; capitula with (15–) 20–30 (–55) flowers; corollas blue to white or infrequently yellow
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2b. Cypsela apically with a slender, elongate beak 1–6 mm long [Fig. 430], the body ± flat; pappus ± white; capitula with 6–24 (–27) flowers; corollas yellow (sometimes blue in age or drying)
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3a. Cypsela body gray or yellow-gray to light brown, with (3–) 5–9 prominent nerves on each face; leaf blades often prickly setose on the abaxial midrib
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3b. Cypsela body brown to dark brown, with 1 prominent nerve on each face, sometimes with an additional pair of faint nerves [Fig. 430]; leaf blades not prickly setose
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4a. Involucre 10–15 mm tall in fruit; cypsela body 4.5–6 mm long including the beak; pappus 5–7 mm long
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4b. Involucre 15–22 mm tall in fruit; cypsela body 7–10 mm long including the beak; pappus 8–12 mm long
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Each photo represents one species in this genus.