COMPOSITAE (COMPOSITE FAMILY) 591 



99. LYGODESMIA Don 



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

 linear 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 or rigid- 

 ulous, sordid-whitish to white. 



Erect perennials. 



None of the branchlets spine-like. 



Involucres 5-flowered, about 10 mm. high . . . . . ] . L. juncea. 



Involucres 6-10-flowered, 15-25 mm. high . . . . . 2. L. grandiflora. 



Some of the branches spine-like . . . . . . . 3. L. spinosa. 



Paniculately branched annual; leaves long and linear . . . .4. L. rostrata. 



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

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

 not spinescent: 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, solitary at the ends of the branches; involucre about 

 10-12 mm. high, the bracts usually gland-tipped: achenes narrowly columnar 

 or shortly tapering to the summit; pappus light brown. Dry plains; widely 

 distributed west of the Missouri. 



2. Lygodesmia grandiflora T. & G. Fl. 2: 485. 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, only the very uppermost reduced to scales: involucre fully 20-25 mm. 

 long, 6-10-flowered: ligules of equal length, showy, rose-red. Gravelly hills; 

 Wyoming and Colorado to Utah. 



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

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

 perennial 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 more numerous, rather loose, 

 lanceolate; the unequal and more imbricated calyculate ones comparatively 

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

 upward, 4-5-costate; pappus 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 dm. high, stria te, 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 peduncles; involucre 8-9-flowered, of as many very 

 narrowly 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 diffusely branched annuals, with numerous small heads terminating 

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

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

 flowered, with as many oblong bracts and 1 or 2 small calyculate ones. Achenes 

 gradually tapering downward from the truncate summit, 4-5-ridged. Pappus 

 of white, soft, capillary bristles. 



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

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

 small heads terminating short-filiform divergent branchlets or peduncles; 



