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only to the middle: rays broad, over 12mm. long: disk usually purple: the stout tri- 
angular-subulate pappus-scales not longer than the width of the achenes.—Dry up- 
lands and plains, northern and central Texas. 
2. T. ambiguum Gray. Rather rigid, usually more naked above or with longer 
peduncles: cauline leaves less compound, the lobes from filiform to narrowly linear: 
bracts of inner involucre connate to or above the middle: rays rarely wanting: 
otherwise as in the last.—Plains and hills of western Texas. 
3. T. gracile Gray. More rigid, less branched, naked above: leaves once or twice 
3 to 5-nately divided or parted into filiform-linear or broader lobes, or some upper 
ones filitorm and entire: bracts of outer involucre 4 to 6, very short, ovate or ob- 
long; of the inner connate to above the middle: rays usually none, sometimes present 
and 4 to 6 mm. long: disk mostly yellow: the lanceolate-subulate retrorsely hispid 
awns of the conspicuous pappus often nearly as long as the corolla-tube.—Plains, 
throughout southern and western Texas. 
** Lobes of disk-corollas ovate to oblong, decidedly shorter than the cylindraceous throat : 
pappus shorter and more coroniform, destitute of retrorse bristles or hairs, or wanting. 
4, T. subsimplicifolium Gray. Leafy-stemmed and branching, herbaceous to the 
ground: stems slender and rigid: leaves sometimes all entire and filiform, sometimes 
3 to 5-parted into filiform entire lobes: outer involucral bracts oblong to linear, 
short: rays 12 mm. long: pappus 2 minute slightly hairy teeth, or obsolete.—Rocky 
prairies of southern and western Texas, 
5. T. longipes Gray. Fastigiately much branched and very leafy at the woody 
base, sending up long filiform simple peduncles 12.5 to 25 cm. long: leaves 3 to 
5-parted into filiform divisions which are usually no wider than the rhachis: heads 
small and rayless; outer involucre short and small: achenes barely 4 mm. long, 
arcuate at maturity: pappus obsolete.—Dry hills and banks of western Texas. 
77. MARSHALLIA Schreb. 
Smooth and low perennials, with alternate entire 3-nerved leaves, 
long-pedunculate many-flowered heads terminating the simple stem or 
branches, flowers (purplish) all tubular and perfect, linear-lanceolate 
foliaceous involucral bracts, convex or conical receptacle with narrowly 
linear rigid chaff, top-shaped 5-angled achenes, and pappus of 5 or 6 
membranaceous and pointed chaffy scales. 
1. M. cespitosa Nutt. Stem commonly leafy only at base: leaves narrowly 
oblanceolate to linear or the radical spatulate, obtuse.—Extending from Arkansas into 
northern and western Texas. 
78. CLAPPIA Gray. 
Fruticulose plant, with alternate fleshy leaves, pedunculate heads, 
broad and very obtuse involucral bracts imbricated in 2 or 3 series, 
convex fimbrillate naked receptacle, 12 to 15 linear 3-toothed fertile 
rays, oblong-turbinate terete 8 to 10-nerved achenes (hirtellous on the 
nerves), and pappus of 20 to 25 rigid scabrous distinct chaffy bristles 
longer than the achene. 
1. C. suzedzfolia Gray. Low and widely branching, not punctate or glandular: 
leaves terete, linear, entire, or the lower pinnately 3 to 5-parted, sessile.—Southern 
Texas. On the Rio Grande at Laredo (Berlandier), and flats of the Pecos (Havard). 
