CAKDUACEAE 1203 



41. APHANOSTEFHUS 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 corolla-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. A. humilis. 



Stems hispidulous : inner achenes obscurely if at all ribbed. 3. A. ramosissimus. 



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

 more or less diffusely 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 pinnatifid, 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 ground, 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 gaudy 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. Keceptacle 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 campe~stris (T. & G.) A. Gray. Plant finely hirsute, at first 

 acaulescent, 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-flowers 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. Pappus 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. 



