CARDUACEAE 1265 



b. Leaf-blades merely hirsute beneath. 



Leaf-blades narrowed into petiole-like bases. 



Leaves prevailingly alternate. 39. H. giganteus. 



Leaves prevailingly opposite. 



Bracts of the involucre acute or slightly acuminate. 40. H. resinosus. 

 Bracts of the involucre with slender, lax tips. 41. if. tracheliifoUus. 



Leaf-blades rounded at the base and markedly petioled. 42. H. hirsutus. 

 B. Leaf-blades closely sessile and partly clasping. 



Stem glabrous or merely scabrous : leaf-blades 3-ribbed from the 



base. 43. H. divaricatus. 



Stem hirsute : leaf-blades 3-ribbed from a point below the middle. 44. H. mollis. 



1. Helianthus d6bilis Nutt. Annual, moi"e or less scabrous. Stems branched at 

 the base, the branches decumbent or spreading, 3-9 dm. long : leaves mostly alternate ; 

 blades deltoid or somewhat hastate to ovate-lanceolate, 4-8 cm. long, actite or acuminate, 

 repand or shallowly and broadly toothed, broadly cuneate to cordate at the base, the 

 petioles glabrous or sparingly pubescent, bracts of the involucre lanceolate or linear-lanceo- 

 late, 8-10 mm. long, acuminate or subulate-tipped : ray-flowers several ; ligules yellow, 

 1-1.5 cm. long : disk 1.5-2 cm. broad. 



In sandy soil, Florida to Texas. Spring and summer. 



2. Helianthus pra^cox Engelm. & Gray. Similar to the preceding species in habit. 

 Branches, petioles and peduncles hirsute, sometimes copiously so : leaf-blades sharply or 

 prominently toothed. 



In sandy soil, near the coast, Florida to Louisiana and Texas. Spring and summer. 



3. Helianthus cucumerifoliua T. & G. Annual, similar to the two preceding species 

 in habit. Branches mottled : leaves mostly alternate ; blades deltoid to ovate or ovate- 

 lanceolate, 3-8 cm. long, acuminate or sometimes only acute, sharply, irregularly and 

 saliently toothed, truncate or subcordate at the base, petioled : bracts of the involucre nar- 

 rowly lanceolate to linear-lanceolate, 1-1.5 cm. long, attenuate into filiform tips: ray- 

 flowers several ; ligules mostly 2-3 cm. long : disks 2-2.5 cm. broad. 



In open woods, Texas. Spring and summer. 



4. Helianthus argophyllus T. & G. Annual, clothed with white, often somewhat 

 floccose silky wool. Stems 5-12 dm. tall, branched : leaves alternate except some of the 

 lower ones ; blades various, those of the lower leaves very broad, those of the upper leaves 

 ovate or lanceolate, 5-15 cm. long, acute, undulate or somewhat serrate, rounded or cordate 

 at the base, petioled : bracts of the involucre oblong, ovate or fiddle-shaped, spreading, 

 1-1.5 cm. long, acuminate, sometimes sharply so : ray-flowers several ; ligules 2.5-3.5 cm. 

 long : disk 2-4 cm. broad. 



In dry soil, Texas. 



5. Helianthus petiol^ris Nutt. Annual, more or less scabrous-pubescent. Stem 3- 

 9 dm. tall, usually branched, scabrous : leaves alternate above the lower part of the stem ; 

 blades oblong-lanceolate to ovate-lanceolate, 3-9 cm. long, merely undulate or shallowly 

 toothed, narrowly or broadly cuneate at the base, long-petioled : bracts of the involucre not 

 hirsute, lanceolate to oblong-lanceolate, 8-12 mm. long, acute or slightly acuminate : ray- 

 flowers several ; ligules 1.5-2.5 cm. long : disk 2-3 cm. broad. 



^In dry soil, Saskatchewan to Minnesota, Texas and Arizona, and rarely naturalized eastward. 



6. Helianthus dnnuus L. Annual, markedly ptibescent. Stem hispid or hirsute, 

 1-2 m. tall, or taller in cultivation, branched above : leaves mainly alternate ; blades 

 broadly ovate, 7-30 cm. long, or smaller above, usually slightly acuminate at the apex, de- 

 cidedly toothed, those of the lower leaves cordate at the base, those of the upper cuneate : 

 bracts of the involucre ovate to oblong or oblong-lanceolate, long-acuminate, hirsute : 

 ligules of the ray-flowers 2.5-5 cm. long : disk flat, 3-5 cm. broad. All the parts are often 

 much larger in cultivated forms. 



In dry soil, Saskatchewan to Minnesota, Texas and Mexico. Adventive eastward. 



7. Helianthus Floridanus A. Gray. Annual, sparingly pubescent. Stem 1-2 m. 

 tall, branched above, smooth and glabrous almost to the peduncles : leaf-blades thin, nar- 

 rowly lanceolate to linear-elliptic, linear-oblong or broadly linear, 4-11 cm. long, acute or 

 slightly acuminate at both ends, remotely and shallowly but quite evenly toothed, often 

 with scattered marginal cilia and spreading hairs along the midrib beneath : bracts of the 

 involucre lanceolate, each prolonged into a slender tip, glabrous except the margins, the 

 larger ones fully 1 cm. long : disk dark purple, 1.5-2 cm. broad ; ligules of the ray-flowers- 

 bright yellow, 2-3 cm. long. 



In sandy, often moist soil, peninsular Florida. Throughout the year. 



8. Helianthus filiformis Small. Perennial, glabrous to the inflorescence. Stems 4-8 

 dm. tall, simple or sparingly branched above : leaves very numerous : approximate ; blades 

 very narrowly linear or coarsely filiform by the revolute margins, 5-10 cm. long, curved, 



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