4 
vRARACUM COMPOSITE 403 
LACTUCA 
110 TARAXACUM Haller Stirp. Helv. i, 23. 
Acaulescent perennial herbs with rosulate leaves, naked scapes 
that elongate in fruit, and mostly large heads of yellow flowers. 
Heads many-flowered, usually solitary at the summit of the sim- 
. ple hollow scapes. Involucrea single series of nearly equal narrow 
bracts that are slightly united at base, and several or numerous 
calyculate ones. Receptacle flat, naked. Achenes oblong-ovate 
or fusiform, 4-5-costate or angled, and usually with some inter- 
vening nerves, muricate or spinulose, at least near the summit 
which is abruptly contracted into a cya ten beak. Pappus soft 
and capillary, dull white. 
T. orricINALE Webber Prim.Pl. Holst. 56. Scapes and leaves from the 
crown of a thick vertical root: leaves from spatulate-oblong to lanceolate in 
outline, and from irregularly dentate to runcinate pinnatifid, 3-10 inches 
long: bracts of the involucre linear-lanceolate, not glaucous, the outer re- 
flexed, all acute: achenes greenish-brown, fusiform, squamulose toward 
the summit, abruptly contracted into a conical apex which is prolonged 
into a filiform beak 2 or 3 times as long as the achene. Common in fields 
and waste places. Naturalized from Europe. 
111 RAFINESQUIA Nutt. Trans. Am. Phil. Soc. vii, 429. 
Leafy-stemmed annuals with pinnatifid leaves and rather large 
heads of white or flesh-colored flowers terminating the paniculate 
branches.. Heads 15-30-flowered. Involucre conical or cylind- 
raceous, of 7-15 equal linear attenuate principal bracts and some 
loose calyculate ones. Receptacle flat and naked Achenes terete, 
somewhat fusiform, obscurely few-ribbed, attenuate into a slender 
beak, the broad base hollowed but not callous-thickened at the 
insertion. Pappus of 10-15 capillary bristles, softly long-plum- 
ose from the base to near the tip. 
R. Californica Nutt. 1. c. Glabrous throughout: stem stout, much 
branched, 2-3 feet high: leaves oblong; the lower 4-6 inches long; the up- 
per gradually reduced to’small bracts: involucre becoming thick at base and 
more or less conical; its rather numerous calyculate bracts subulate and 
spreading: ligules short, white: achenes tapering into a very slender beak 
as long as the body: pappus dull white, the bristles fine and soft. Shady 
ground, eastern Oregon to California. 
112 LACTUCA Tourn. Inst. t. 267. L. Gen. n. 909. 
Tall herbs with alternate leav2s and small panicled heads of 
yellow white or blue flowers. Involucre cylindric, several to 
many-flowered, either calyculate or more regularly imbricated. 
Receptacle flat, naked. Achenes flat, 3-5-ribbed on each face, 
narrowed above, or contracted into a narrow beak, which is more 
or less expanded at the summit into a small disk that hears the 
copious white or brownish pappus bristles which fall separately. 
§ 1 Scartota DC. Prodr. vii, 188. Achenes very flat, orbic- 
ular to oblong. abruptly produced into a filiform beak which 
bears the soft white pappus on its dilated apex. 
