CARDUACEAE 1203 



41. APHANOSTEPHUS DC. 



Annual or biennial, or probably perennial caulescent herbs, with pubescent foliage. 



Leaves alternate : blades entire, toothed or pinnately lobed. Heads radiate. Involucres 



many-flowered, hemispheric : bracts narrow, in few series, scarious-margined. Keceptacle 



convex or conic. Ray-flowers pistillate, with white violet or purple ligules. Disk-flowers 



perfect, yellow. Anthers obtuse at the base. Stigmas with obtuse appendages. Achenes 



many-ribbed. Pappus an entire toothed or ciliate crown. 



Pappus a toothed or laciniate crown : base of the eorolla-tube hard and thick. 1. A. skirrobasis. 

 Pappus a short ciliate crown : base of the corolla-tube barely thickened. 



Stems softly pubescent : inner achenes prominently ribbed. 2. ^1. humilis. 



Stems hispidulous : inner achenes obscurely if at all ribbed. S. A. ramosissimus. 



1. Aphanostephus skirrobasis ( DC. ) Trelease. Foliage cinereous-pubescent. Stems 

 more or less difi'usely branched at the base, 1-4 dm. long : leaf -blades spatulate, oblong or 

 linear, 1.5-6 cm. long, the lower ones sharply toothed or incised, the upper entire : heads 

 showy, long-peduncled : involucres 5-6 mm. high, hemispheric ; bracts linear or narrowly 

 linear-lanceolate, the outer ones minutely pubescent : ray-flowers many ; ligules linear : 

 achenes pubescent with a pappus of several lobes or teeth. 



On plains, Kansas to Texas and in Florida. Spring and summer. 



2. Aphanostephus humilis (Benth. ) A. Gray. Foliage softly pubescent. Stems 

 branched at the base ; branches 1-3 dm. long, often decumbent : leaf-blades i^innatifid, or 

 entire above, 1-6 cm. long : i heads slender-peduncled : involucres hemispheric, 3-4 mm. 

 high ; bracts linear, acute, ribbed, minutely pubescent : ligules of the ray-flowers 4-8 mm. 

 long, linear-oblanceolate. 



In dry groinid, Texas and adjacent Mexico. 



3. Aphanostephus ramosissimus DC. Foliage hispidulous. Stems often diffusely 

 branched at maturity, 1-3 dm. long ; leaf-blades various, those of the basal or lower stem- 

 leaves 5-10 cm. long, spatulate, pinnatifid or incised ; those of the upper leaves linear, 

 mostly entire, sessile : heads long-peduncled : involucres hemispheric, 4-5 mm. high ; 

 bracts linear or narrowly linear-lanceolate, the outer often pubescent : ligules of the ray- 

 flowers 6-10 mm. long, linear-spatulate. 



On sandy or rocky prairies, Texas and adjacent Mexico. 



42. DICHAETOPHORA A. Gray. 



Annual relatively low caulescent or scapose herbs. Leaves alternate, sometimes mainly 

 basal : blades broadened upward, entire. Heads radiate, sometimes solitary. Involucres 

 many-flowered : bracts in about 1 series. Receptacle a little convex, pitted. Ray-flowers 

 numerous, pistillate, fruit producing, with white or pink ligules. Disk-flowers perfect. 

 Anthers entire and obtuse at the base. Stigmas flattened, with triangular-lanceolate ap- 

 pendages. Achenes flattened, broadened upward, pubescent. Pappus of 2 spreading awns 

 and several minute scales, usually hidden by the pubescence of the achene. 



1. Dichaetophora camp6stris (T. & G.) A. Gray. Plant finely hirsute, at fii-st 

 acauiescent, with a single scape, later somewhat branched, each branch terminating in a 

 peduncle 3-6 cm. long which bears a single head : leaf-blades spatulate to oblong-spatu- 

 late, 1-3 cm. long, entire : involucre 3-4 mm. high ; bracts linear, slightly acuminate, 

 sparingly pubescent : ray-flowei's 10-20, with white or pink ligules 5-8 mm. long : achenes 

 cuneate, 1.5 mm. long, margined, ciliate. 



In dry soil, southern Texas and adjacent Mexico. Spring to fall. 



43. BOLTONIA L'Her. 



Perennial large caulescent herbs, with glabrous foliage. Leaves alternate : blades 

 narrow, entire, sessile and sometimes decurrent. Heads often numerous, radiate. In- 

 volucres broadly campanulate or hemispheric, many-flowered : bracts in few series. Re- 

 ceptacle convex or conic, pitted. Ray-flowers often numerous, pistillate. Disk-flowers 

 perfect. Anthers obtuse and entire at the base. Stigmas flattened, with relatively short 

 appendages. Achenes flattened, broadest above the middle, with winged or thickened 

 margins. Papi^us a series of short scales, usually accompanied by 2-4 slender bristles. 



Disk about 4 mm. broad at maturity. 1. B. diffusa. 



Disk 6-12 mm. broad at maturity, 

 a. Leaf-blades merely sessile. 



