CAKDUACEAE 1295 



Scales accompanying the involucres lax and conspicuous : pappus-scales much shorter than the disk- 



corollas. 1. T. tagetoides. 



Scales accompanying the involucres very small or wanting : pappus-scales as long 



as the disk-corollas or longer. 

 Pappus simple or nearly so, the scales 3-awned. 



Pappus-scales 18-20. 2. T. polychada. 



Pappus-scales mostly 10. 



Involucres with 16-20 lobes. 3. T. Wrightii. 



Involucres with about 12 lobes. 4. T. tenuildba. 



Pappus double, the scales obtuse. 



Perennial : foliage glabrous or minutely pubescent, not woolly 



, . 



Shrubby : foliage pubescent : involucres less than 5 mm high. 5. T. pentachaeta,. 



Herbaceous : foliage glabrous or nearly so : involucres over 5 mm. high. 6. T. Treculii. 



Annual : foliage woolly. 7. ^2*. gnaphaloidfs. 



1. Thymophylla tagetoides (T. & G. ) Small. Annual or perennial, glabrous. 

 Stems rigid, 1-4 dm. tall, solitary or tufted : leaves alternate ; blades narrowly linear, 3-8 

 cm. long, remotely spiny-toothed : heads showy : involucres oblong or oblong-campanu- 

 late, 6-8 mm. high ; bracts united to near the tips, acute : ligules of the ray-flowers yellow, 

 1-1.5 cm. long : achenes 3.5-4 mm. long : pappus simple ; scales about 10, rigid, with 

 1-3 awns shorter than the disk-corollas. [Hymenatherum tagetoides T. & G.] 



On prairies, Texas. Spring and summer. 



2. Thymophylla polychaeta (A. Gray) Small. Annual, sparingly pubescent. 

 Stems 0.5-1.5 dm. tall, with several or many ascending branches : leaves alternate ; blades 

 1-3 cm. long, pinnately parted into several narrowly linear or linear-filiform segments : 

 heads relatively small : involucre 4-6 mm. high, broadly campanulate ; bracts united to 

 above the middle, acute; ligules of the ray-flowers yellow, 3-7 mm. long : achenes 4-4.5 

 mm. long : pappus-scales 18-20, various, the smaller terminating in a single awn, the 

 larger with a more elongated awn and a shorter one at each side of its base. 



On prairies, southern Texas,|New|Mexico and adjacent Mexico. Summer and fall. 



3. Thymophylla "Wrightii (A. JGray) Small. Annual* or probably perennial, gla- 

 brate. Stems erect, or branched at the base, the branches decumbent, 5-20 cm. long : 

 leaves alternate ; blades narrowly linear, 1-3 cm. long, bristle-tipped, entire or with few 

 pinnate lobes: involucres campanulate, 5-6.5 mm. high ; lobes 16-20, ovate or triangu- 

 lar : ligules of the ray-flowers bright yellow, 5-9 mm. long : achenes about 4 mm. long : 

 pappus simple or nearly so ; scales about 10, each with three awns from a lanceolate or 

 oblong base, the middle awn about twice as long as the lateral. [Hymenatherum Wrightii 

 A. Gray.] 



In sandy soil or on prairies, Texas. Spring. 



4. Thymophylla temriloba (DC.) Small. Annual or perennial, minutely pu- 

 bescent. Stems 1-3 dm. long, more or less diffusely branched : leaves numerous, rigid ; 

 blades pinnately parted into 7-11 subulate-filiform segments 3-8 mm. long and bristle- 

 tipped : involucres campanulate, 5-6 mm. high ; lobes 12, ovate : ligules of the ray-flowers 

 yellow, 4-6 mm. long : achenes 3-3.5 mm. long : pappus simple or nearly so ; scales about 

 10, 3-awned, the middle awn about as long as the body. [Hymenatherum tenuilobum DC.] 



In sandy soil, Texas and adjacent Mexico. Spring and summer. 



5. Thymophylla pentachaeta ( DC. ) Small. Perennial, pubescent. Stems shrubby, 

 more or less densely branched at the base, the branches 1-2 dm. long : leaves numerous ; 

 blades 1-2.5 cm. long, the segments subulate or nearly filiform : involucres campanulate, 

 4 mm. to nearly 5 mm. high : ligules of the ray-flowers bright yellow, 4-6.5 mm. long : 

 achenes 3.5-4 mm. long : pappus double, the outer scales thin, erose at the top. [Hymena- 

 therum pentachaetum DC.] 



On dry hills, Texas to Utah and Mexico. Summer and fall. 



6. Thymophylla Treculii (A. Gray) Small. Perennial, but rather herbaceous and 

 nearly glabrous. Stems diffusely branched, the branches lax : leaves numerous ; blades 

 pectinately parted, the segments linear-subulate, 4-6 mm. long : heads scattered : involucres 

 5-6 mm. high : achenes, and pappus, similar to those of the next preceding species. 



In dry soil, southeastern Texas. 



7. Thymophylla gnaphaloides (A. Gray) Small. Annual, densely woolly. Stems 

 branched at the base, the branches 0.5-2 dm. long, depressed or diffusely spreading : leaves 

 numerous ; blades spatulate to linear-spatulate, 1-1.5 cm. long, completely clothed with 

 wool : heads rather showy : involucres 6-7 mm. high ; bracts united to near the top, the 

 lobes acute or slender-tipped, punctate : ligules of the ray-flowers yellow, oval or oblong, 

 4-5 mm. long: achenes 3-3.5 mm. long: pappus double, the inner series of lanceolate 

 palae. [Hymenatherum gnaphaloides A. Gray.] 



On dry hills and plains, Texas and adjacent Mexico. Spring to fall. 



