Lactuca serriola |
Lactuca graminifolia |
|
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prickly lettuce |
grass-leaf lettuce |
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Habit | Annuals (perhaps persisting), (15–)30–70(–100+) cm. | Biennials, 25–90(–150+) cm. |
Leaves | on proximal 1/2–3/4 of each stem; blades of undivided cauline leaves usually ± oblong, sometimes obovate to lanceolate, margins denticulate, usually prickly, midribs usually prickly-setose, rarely smooth. |
on proximal 1/3–1/2 of each stem; blades of undivided cauline leaves spatulate to lance-linear, margins entire or denticulate, midribs sometimes setose. |
Involucres | 9–10(–12) mm. |
12–20+ mm. |
Florets | 12–20; corollas yellow, usually deliquescent. |
15–20+; corollas bluish to purplish, usually deliquescent. |
Phyllaries | usually reflexed in fruit. |
usually reflexed in fruit. |
Heads | in paniculiform arrays. |
in ± paniculiform arrays. |
Cypselae | bodies pale grayish to tan, ± flattened, oblanceolate, 2.5–3.5 mm, beaks ± filiform, 2.5–4 mm, faces (3–)5–9-nerved; pappi white, (3–)4–5 mm. |
bodies brown (often mottled), ± flattened, elliptic, 5–6 mm, beaks ± filiform, 2–4 mm, faces 1(–3)-nerved; pappi white, 5–9 mm. |
2n | = 18. |
= 34. |
Lactuca serriola |
Lactuca graminifolia |
|
Phenology | Flowering (May–)Jul–Sep(–Oct). | Flowering (Feb–)Apr–Jun(–Sep). |
Habitat | Roadsides, disturbed sites | Sandy ridges, pine forests, canyons |
Elevation | 10–2300 m (0–7500 ft) | 10–1700 m (0–5600 ft) |
Distribution |
AL; AR; AZ; CA; CO; CT; DC; DE; FL; GA; IA; ID; IL; IN; KS; KY; LA; MA; MD; ME; MI; MN; MO; MS; MT; NC; ND; NE; NH; NJ; NM; NV; NY; OH; OK; OR; PA; RI; SC; SD; TN; TX; UT; VA; VT; WA; WI; WV; WY; AB; BC; MB; NB; NS; ON; PE; QC; SK; Europe [Introduced in North America; also introduced nearly worldwide]
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AL; AZ; CO; FL; GA; LA; MS; NC; NJ; NM; SC; TX; Central America; Mexico (Chihuahua)
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Discussion | The name Lactuca scariola Linnaeus is evidently illegitimate; it is a superfluous name based on the same type as L. serriola. Plants included here in L. serriola with most leaf blades obovate to lanceolate (not lobed) and lacking prickles on midribs have been called L. scariola subsp. or var. integrata or L. serriola forma integrifolia or L. serriola var. integrata. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Plants in the western populations of Lactuca graminifolia have been called L. graminifolia var. arizonica McVaugh; they may belong to a Mexican species. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 19, p. 262. | FNA vol. 19, p. 261. |
Parent taxa | Asteraceae > tribe Cichorieae > Lactuca | Asteraceae > tribe Cichorieae > Lactuca |
Sibling taxa | ||
Name authority | Linnaeus: Cent. Pl. II, 29. (1756) | Michaux: Fl. Bor.-Amer. 2: 85. (1803) |
Web links |
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