1282 CAKDUACEAE 



of the involucre linear-spatulate, equalling the disk, glabrous, the inner usually black- 

 punctate : rays several, the ligules 1-3 cm. long, golden yellow, the ovaries glabrous and 

 awnless : disk-corollas 5-lobed : stamens exserted : achenes very small, 2-4 mm. long, 

 glabrous ; awns very short, tooth-like. [ Coreopsis aurea Ait. ] 



In wet soil, Virginia to Florida and Alabama. Summer and fall B. coronata leptophylla (Nutt.) 

 0. Mohr, a form with narrowly linear and almost or quite entire leaf-segments : and awnless achenes, 

 occurs in brackish places from Florida northward. 



107. COSMOS Cav. 



Annual or perennial caulescent herbs. Leaves opposite : blades entire, lobed or 2-3- 

 pinnately dissected. Heads radiate, peduncled. Involucres nearly hemispheric : bracts 

 thin, imbricated in two series and united at the base, the outer sometimes smaller than the 

 inner. Receptacle flat or scarcely convex. Kay-flowers neutral : ligules pink, purple (or 

 rarely orange-yellow). Disk -flowers perfect, fruit-producing : corollas yellow. Anthers 

 entire or minutely 2-toothed at the base. Stigmas of the disk-flower with slender or tufted 

 appendage. Achenes 5-angled or flattened on the back, beaked. Pappus of 2-4 more or 

 less persistent barbed awns or a crown. 



1. Cosmos caudatus H.B.K. Annual, glabrous or nearly so. Stems 7-14 dm. tall, 

 branched : leaf-blades 2-pinnately parted, the segments lanceolate or linear : involucral 

 bracts linear, acute, the inner often longer than the outer : ray -flowers 7-12 ; ligules rose- 

 colored, 1-2 cm. long, 3-cleft : achenes fusiform, about 2 mm. long, the beak about as long 

 as the body, with 2 awns. 



In sand, Keys of Florida. Native of tropical America. 



108. THELESPERMA Less. 



Annual or perennial herbs, with glabrous or nearly glabrous foliage. Leaves oppo- 

 site : blades narrow, entire, toothed or finely dissected . Heads radiate or sometimes dis- 

 coid, peduncled. Involucres campanulate or hemispheric : bracts in two series, the outer 

 distinct, spreading, the inner larger, partially united into a cup, the tips scarious. Recep- 

 tacle flat, chaffy. Kay-flowers "neutral : ligules yellow, or wanting. Disk-flowers perfect, 

 fruit-producing. Anthers entire at the base. Stigmas with acute cones or cusps. Achenes 

 narrow, terete or slightly flattened, wingless, some or all of them papillose on the back. 

 Pappus of two retrorsely hispid awns or scales, or wanting. 



Disk-corollas with linear or lanceolate lobes longer than the campanulate throat. 



Annual or biennial : outer involucral bracts linear-subulate. 1. T. trifidum. 



Perennial : outer involucral bracts ovate or oblong. 2. T. gracilc. 



Disk-corollas with ovate or oblong lobes, shorter than the cylindric throat. 3. T. subsimplicifolium. 



1. Thelesperma trifidum (Poir. ) Britton. Annual or biennial. Stems 2-7 dm. 

 tall, loosely branched : leaf-blades 3-10 cm. long, 2-pinnately divided, the segments linear- 

 filiform or filiform, not broader than the rachis : involucral bracts various, the outer 

 linear-subulate, the inner united to the middle, usually fully as long as the outer : ray- 

 flowers 6-9 ; ligules yellow, 1-1.5 cm. long: disk purple, turning brown : achenes of the 

 outer part of the disk 4 mm. long, strongly papillose on the back : pappus-scales triangular- 

 subulate, as long as the width of the achene. 



On dry hills and plains, Arkansas and Texas. Spring and summer. 



2. Thelesperma gracile (Torr. ) A. Gray. Perennial. Stems 3-8 dm. tall, sparingly 

 branched : leaf-blades 3-7 dm. long ; blades 1-2-parted or divided, the segments entire, 

 filiform or narrowly linear : involucral bracts various, the outer 4-6, ovate or oblong, the 

 inner united to above the middle ; ligules of the ray-flowers yellow, 4-6 mm. long, or 

 wanting : disk yellow, turning brown : achenes 6-6.5 mm. long, the slender awns longer 

 than the width of the achenes. 



On plains, Wyoming to Nebraska, Texas and Arizona. Spring and summer. 



3. Thelesperma subsimplicifolium A. Gray. Perennial. Stems 3-7 dm. tall, 

 loosely branched : leaf-blades 3-8 cm. long, entire and narrowly linear or linear-filiform, 

 or 3-5-parted, the segments as wide as the rachis entire : involucral bracts various, the 

 outer linear to oblong, the inner united to about the middle : ligules of the ray-flowers 

 yellow, cuneate, 10-12 mm. long : achenes fusiform, 4-5 mm. long : pappus obsolete, or of 

 2 minute pubescent teeth. 



In dry or stony soil, Texas to Arizona and adjacent Mexico. Spring and summer. 



