3. Lactuca hirsuta Muhl. ex Nutt. (downy lettuce, hairy lettuce)
Pl. 258 e, f;
Map 1079
Plants usually
biennial. Latex light tan to pale orange. Stems 30–200 cm long, hollow between
the nodes, glabrous to densely pubescent with relatively long, curled hairs,
often purple-streaked or purplish-tinged. Leaves best-developed toward the stem
base, reduced in size and often unlobed above the stem midpoint, the basal and
lower stem leaves mostly 10–20 cm long, with a winged petiole, ovate or obovate
in outline, deeply pinnately lobed and sharply toothed, the margins sparsely
hairy, sometimes with a pair of narrowly to broadly triangular basal lobes
clasping the stem, the surfaces usually short-hairy, less commonly only
sparsely hairy on the undersurface midvein. Inflorescences mostly well-branched
panicles with (15–)25–100 heads, occasionally appearing nearly racemose.
Involucre cylindrical or urn-shaped, 13–20 mm long at flowering, elongating to
15–22 mm at fruiting, the bracts 17(–19). Florets (12–)15–20(–22). Corollas
yellow to orangish yellow, sometimes turning blue with age or upon drying.
Pappus 7–10(–12) mm long. Fruits with the body 3–5 mm long, 2.0–2.5 mm wide,
dark brown to black, flattened, with prominent lateral wings and a conspicuous
ridge on each face, tapered abruptly to a slender beak somewhat shorter than to
about as long as the body. 2n=34. June–September.
Uncommon in the
Ozark and Ozark Border Divisions (eastern U.S. west to Illinois and Texas;
Canada). Mesic to dry upland forests, savannas, sand savannas, and margins of
sinkhole ponds; also roadsides.
This species is
similar to L. canadensis but tends to be hairier and to have larger
involucres and fruits. It also has the leaves more basally disposed. Several
infraspecific taxa have been described based on the extent of hairiness and the
colors of florets. Two phases that occur in the state are var. hirsuta,
with stems and both sides of the leaves hairy, and var. sanguinea
(Bigelow) Fernald, with stems glabrous or nearly so and leaves glabrous or
sparsely hairy along the midvein on the undersurface. These variations seem
unworthy of formal taxonomic recognition, and intermediates exist.