te 
444 DESCRIPTIONS OF NEW SPECIES 
Galathenium sanguineum. Lactuca sanguinea, BiceEt. Flor. Bost., (ed. 2,) 
p. 287. Leaves very often nearly all entire, or only runcinately toothed ; ache- 
nium one-nerved, black. 
Balshentum ludovicianum. Sonchus ludovicianus, Nutt. Gen. Am., Vol. IL., 
p. 125. 
Ozs. The plants of this genus (peculiarly North American) appear to be 
intermediate between Lactuca and Mulgedium. From Lactuca they differ 
wholly in the achenium, which, in L. sativa and others, is of a pale colour, 
and covered with longitudinal striatures. In Lactuca perennis, however, the 
striatures are few, and the achenia has a tumid margin, as in Mulgedium, but 
it is also furnished with a very long rostrum. From:Mulgedium our plants 
differ in the form, compression, colour, and margin of the achenium, as well 
as in the presence of an abrupt and distinct rostrum, seldom, if ever, the length 
of the elliptic fruit, and of a different colour and consistence with the ache- 
nium. 
LYGODESMIA. (Don.) 
Subgenus *Pretacanruus.—Capitulum four to five-flowered. Involucrum 
_ eylindric-ovate, imbricate, of a few unequal, flat, lanceolate sepals, the ex- 
ternal so short as to appear like a caliculum. Receptacle minute, naked. 
Achenium subcylindric, obtusely five-ribbed, truncated. _Pappus bristly and 
barbellate, yellowish-white, long, and in several series.—A nearly leafless, 
divaricately branched, rigidly spiny perennial, with rose-red flowers in short 
racemes. Probably a distinct genus. 
Lygodesma * spinosa; stem divaricate; branchlets spinescent, microphyllous; 
capituli subracemose, with an irregular involucellum. 
Has. In the Rocky Mountain plains towards California. About eight to fourteen inches high. 
Lower leaves linear, entire, sessile, rather thick; upper leaves and those on the spiny branchlets 
minute, like very small bractes. Stem divaricate and spreading, the base somewhat pubescent and 
producing remarkably large tufts of brownish matted down; the bud scales broad ovate. Flowers 
‘pedicellate, in racemes. - Every branch and twig ends in a spiny point. Larger leaves of the in- 
 voluerum: three or four, ovate, or ovate-lanceolate, three or four smaller ones at the base of. the 
involucrum. © Florets rose-red, deeply five-cleft at the summit. Stigmas filiform, exserted, pubes- 
cent. Pappus rigid and barbellated. 
