COMPOSITAE (CUMPOSITK I^ApiLV) 591 



99. LYGODESMIA Don 



Mostly smooth and glabrous, with usually rush-like rigid or tough stems, 

 Unear or scale-like leaves, and terminal or scattered heads which are always 

 erect. Heads 3-12-flowered, erect, the flowers pink or rose-color. Achenes 

 terete, obscurely few-striate or angled, commonly linear or slender-fusiform. 

 Pappus of copious and usually unequal capillary bristles, either soft dr rigid- 

 ulouSj sordid- whitish to white. 



Erect perennials. ' . 



None of the branchlets spine-like. 



Involucres 5-flowered, about 10 mm, high , . , ; , J^ L. junpea. 



Involucres 6-10-flowered, 15-25 mm. hi^h . ... . 2. L. grandi'flora. 



:'. Some of the branches spine-like •■ , : . ','.'. .3. L. spinosa. 



Faniculately branched annual; leaves long and linear . . , . 4. L. rostrata. 



1. Lygodesmia junceaDon. Edinb.Phil. Journ. 6: 311. 1829. Perennial by 

 a thick woody root; Stems stiff, much-branched, 1-4 dm. high, striate-angled, 

 not spineseeflt: lower leaves lanceolate, rigid, entire, acute or acuminate, 

 1-4 cm. long; the upper similar but smaller, or reduced to subulate scales: 

 heads mostly 5-flowered, sohtary at the ends of the branches; involucre about 

 10-12 mm. high, thie bracts usually gland-tijJped: achenes narrowly columnar 

 or shortly ta,pering to the summit; pappus hght brown. — ^Dry plains; widely 

 distributed west of the Missouri. 



2. Lygodesmia grandiflora T. & (3. Fl. 2: 4815.^ 1842. Stems separate or 

 few from the root, simple below, 1-3 dm. high; the'larger plants leafy, corym- 

 bosely branched above, and bearing few or numerous short-pedunculate 

 heads: leaves all entire, of firm and thickish texture, linear-attenuate, 5-10 cm. 

 long, oiily the very uppermost reduced to scales: involucre fully 20-25 mm. 

 long, 6-lO-flowered: hgules of equal length, showy, rose-red .^Gravelly hills; 

 Wyoming and Colorado to Utah. 



3. Lygodesmia spinosa Nutt. Trans. Am. Phil. Sop. 7: 444. 1841. Stems 

 slender^ rigid, low, much-branched from an indurated and matted-woolly 

 perenmal base, otherwise glabrous; branchlets divergent, spinescent, bearing 

 minute scales in place of leaves, and lateral, Very short-peduncled heads: 

 lower cauline leaves linear, entire, thickish, above soon reduced to scales: 

 involucre 3-5-flowered; the principal bracts not morfe numerous, rather loose; 

 lanceolate; the unequal and more inibricated calyculate ones compai'atively 

 broad and large: achenes much shorter than the pappus, not at all narrowed 

 upward, 4-5-costate; palppus white, of unequal bristles. — Gravelly hills and 

 plains; eastern Oregon to California, Nevada, and Idaho. 



4. Lygodesmia rostrata Gray, Proc. Am. Acad. 9: 217. 1874. Stem erect, 

 2-7 dn). high, striate, leafy, corymbose-paniculate: leaves narrowly linear, 

 attenuate to both ends, entire, obscurely 3-nerved; the cauline 8-15 cm. long, 

 barely 3-4 mm. wide; the uppermost slender-subulate: heads numerous. On 

 scaly-bracteolate erect peditocles; involucre 8-9-flowered, of as many very 

 naiTowly linear bracts: rays small and narrow, probably purplish: achenes 

 slender-fusiform, distinctly attenuate at summit, longer than the soft, rather 

 dull white pappus. — ^Plains; from the Saskatchewan to Wyoming and Colorado. 



100. PRENANTHELLA Rydb. 



Low (iiffusely branched annuals, with numerous small heads terminating 

 the branches. Lower leaves ample, oblolig or spatulate in outline, more or 

 less nincinate; the upper reduced and bract-like. Involucres oblong, 4-5- 

 flowered, with as many'oblong bracts and 1 or 2 smaU.calyculate ones, ^henes 

 gradually tapering downward from the truncate summit, i4-5-ridged.. Pappus 

 of white, soft, capillary bristles, ■ . 



1. Prenanthella exigua (Gray) Rydb. Bull. Torr, Bot: Cltib 33: 161. 1906. 

 Stems 1-2 dm, high, effusely paniculate from the base, bearing numerous 

 small heads terminating short-filiform divergent branchlets or peduncles; 



