484 COMPOSITiE. Ltgodesmia. 



190. LYGODESMIA. Don, in Edinb. phil. jour. 6. p. 305 (excl. spec.) ; 

 Hook.ji. Bor-Am. l.p. 295; DC. 



Lygodesmia & Erythremia, Nutt. 



Heads 5-10-flowered. Involucre elongated cylindrical, of 5-8 linear scales 

 in a single series, and calyculate with a few very short imbricated bracteolate 

 scales. Receptacle scrobiculate. Branches of the style much exserted. 

 Achenia linear, elongated, somewhat cylindrical, striate, smooth, not contracted 

 at the apex. Pappus of very copious and scarcely scabrous whitish capillary 

 bristles, in many series, rather persistent. — Perennial glabrous and some- 

 what glaucous rigid branching herbs (natives of sterile plains chiefly beyond 

 the Mississippi), with the habit of Chondrilla: the leaves linear or subulate,- 

 entire ; those of the branchlets reduced to mere scales. Root perpendicular. 

 Heads solitary terminating the stem or branches, erect. Flowers reddish- 

 purple or rose-color. 



This genus differs from Prenanthes and Nabalus rather in its striking habit than 

 in any mai'ked or important floral characters. 



§ 1. Heads 5-Jiowered : pappus soft: stems very muck branched, not spines- 

 cent. EULYGODESMIA. 



1. L. juncea {J)oxi\ I.e.): stems very much branched, striate; lower 

 linear-sublanceolate, rigid ; the upper subulate. — Hook. ! ji. Bor.-Am. 1. 

 p. 295, t. 103 ,• DC. prodr. 7. p. 198. Prenanthes juncea, Pursh ! jl. 2. 

 p. 498; Nutt. ! gen. 2. p. 123. 



Plains of the Missouri and Platte to the Rocky Mountains, Lewis? Nut- 

 tall ! Dr. James ! Lieut. Fremont ! and of the Saskatchawan, Drummond! 

 May-June. — About a foot high. Lower leaves 1-2 inches long. Flowers 

 purple according to Pursh, rose-color according to Nuttall, blue according to 

 Hooker. Pappus extremely copious, at first nearly white ; the soft slender 

 bristles scarcely at all scabrous. Mature achenia slender, half an inch 

 jOng. 



§ 2. Heads A-5-flotvered : pappus rather rigid : stems divaricately much 

 branched: the branchlets spinescent. — Pleiacanthus, Nutt. 



2. L. spinosa (Nutt.) : stem and branches not striate, rigid; lower leaves 

 linear, thickish ; those of the branches reduced to minute bracts ; proper 

 scales of the rather short cylindraceous involucre about 4, lanceolate ; the 

 calyculate scales conspicuous, ovate. — Nutt. ! in trans. Amer. phil. soc. 

 {n. ser.) 1. p). 444. 



Plains of the Rocky Mountains towards California, Nuttall! — A span to a 

 foot high, divaricate and spreading ; " the base somewhat pubescent, and 

 producing remarkably large tufts of brownish matted down." Nutt. 

 Flowers rose-red. Pappus less copious and more rigid than in the preceding, 

 by no means barbellate, as described by Nuttall, but appearing very slightly 

 scabrous under a good lens. Mature achenia not seen. 



