552 COMPOSITAE (COMPOSITE FAMILY) 



Leaves largely basal; pappus nearly or quite obsolete . . . 3. T. sub mid um. 

 Leaves filiform-linear; plant annual, biennial, or short-lived perennial 4. T. trifidum. 



1. Thelesperma gracile (Torr.) Gray, Kew Journ. Bot. 1: 253. 1849. 

 Rather rigid, 3-6 dm. high, from a deep root, branched, naked above: leaves 

 once or twice ternately or quinately divided or parted into filiform-linear or 

 broader lobes, or some upper ones filiform and entire: bracts of the outer in- 

 volucre 4-6, very short, ovate or oblong; those of the inner one connate to 

 above the middle, the edges of their lobes slightly scarious: disk mostly yellow, 

 barely brownish after anthesis: achenes slightly papillose or roughened, the 

 breadth of the summit exceeded by the subulate awns: rays usually none, 

 rarely present and 4-5 mm. long. On the plains; Montana to Arizona and 

 Texas. 



2. Thelesperma ambiguum Gray, Proc. Am. Acad. 19: 16. 1883. Stems 

 3-5 dm. high, rather rigid: leaves bipinnately divided into narrowly linear 

 or filiform lobes: bracts of the outer involucre 8, subulate-linear, almost 

 equaling or half the length of the inner, which are connate to or above the 

 middle: rays broad, 10-15 mm. long, rarely wanting: disk usually purple, 

 turning brownish: outer achenes becoming coarsely papillose; the stout pappus- 

 scales not longer than the width of the achene. (T. intermedium Rydb. Bull. 

 Torr. Bot. Club 27: 631. 1900.) Montana to New Mexico and Texas. 



3. Thelesperma subnudum Gray, 1. c. 10: 72. 1874. Rather stout: leaves 

 thickish and rigid, once or twice ternately parted into linear or lanceolate 

 lobes: peduncles 1-2 dm. long; head 12 mm. high: rays sometimes none, 

 sometimes ample: pappus a minute, 4-5-toothed naked crown, or obsolete. 

 Wyoming to New Mexico and Arizona. 



4. Thelesperma trifidum (Poir.) Brit. Trans. N. Y. Acad. Sci. 9: 182. 

 1890. Stems 3-5 dm. high, loosely branching, leafy: leaves not rigid, bipin- 

 nately divided into filiform lobes no wider than the rachis: bracts of the outer 

 involucre 8, subulate-linear, almost equaling or more than half the length of 

 the inner, which are connate only to the middle: rays broad, 12-15 mm. long: 

 disk usually purple, turning brownish: outer achenes becoming coarsely 

 papillose on the back; the stout triangular-subulate pappus-scales not longer 

 than the width of the achenes. (T. tenue Rydb. 1. c.) Dry plains; Colorado 

 to Arkansas and Texas. 



59. MADIA Molina. TARWEED 



Glandular and viscid herbs, mostly heavy-scented, with entire or merely 

 toothed leaves, some or all of them alternate. Heads axillary and terminal, 

 many-several-flowered. Involucre ovoid or oblong, few to many-angled by 

 the salient narrow backs of the involucral bracts. Receptacle flat or convex, 

 bearing a single series of bracts inclosing the disk-flowers as a kind of inner in- 

 volucre, either separate or connate into a cup. Ray flowers 1-20, with cuneate 

 or oblong 3-lobed ligules; the achenes laterally compressed, and inclosed 

 in conduplicate-infolded involucral bracts. Ours belongs to the section 

 Eumadia, in which the rays are few and inconspicuous or none and the pappus 

 mostly wanting. 



1. Madia glomerata Hook. Fl. 2: 24. 1834. Stems 2-5 dm. high, rigid, very 

 leafy, hirsute, glandular only toward the inflorescence: leaves narrowly linear: 

 heads glomerate: rays 2-5 or sometimes none, not surpassing the about equal 

 number of disk-flowers: achenes narrow; those of the disk 4-5-angled; those of 

 the ray somewhat curved and 1-nerved on each face. Mountains of Colorado, 

 to the Saskatchewan, the Sierras of California, Oregon, and Washington. 



60. LAYIA H. & A. 



Branches terminated by showy heads of (in ours) white flowers. Herbage 

 hispid or- hirsute, somewhat viscid above, beset with scattered, stipitate, black- 

 ish glands. Heads many-flowered, broad. Ray-flowers 8-20, with 3- lobed or 



