CARDUACEAE. 303 



yellow, 2-2.5 cm. long: achenes obovate or oblong-obovate, 8-10 mm. long, 

 narrowly winged. — Lower Susquehanna valley. Rare, in sandy soil. — 

 Schists. — Sum. — • Rosin-weed. 



28. CHRYSOGONUM L. Perennial depressed small herbs. Leaves oppo- 

 site: blades toothed. Heads erect. Involucre hemispheric: bracts distinct, 

 the outer foliaceous. Ligules of the ray- corollas yellow. Disk-flowers with 

 short abortive ovaries and corollas with a very short tube and funnelform 

 throat. Filaments less than half as long as the anthers. Style glabrous. 

 Achenes wingless. Pappus a half cup-shaped crown. 



1. C. virginianum L. Stems hirsute: leaf -blades oblong, ovate or oval, 2-5 

 cm. long, long-petioled: involucre hirsute; outer bracts 7-10 mm. long: ligules 

 of the ray mostly 9-11 mm. long: achenes 4-4.5 mm. long. — S. Rare, on 

 hillsides along the Octoraro Creek. — Schists. — Spr. and sum. 



29. PARTHENIUM L. Perennial or annual herbs, or shrubs. Leaves 

 alternate: blades toothed, pinnatifid, or dissected. Heads inconspicuously 

 radiate. Involucre depressed to globular: bracts appressed, broad, Ray- 

 flowers usually 5 : ligules small or minute, white or whitish. Lobes of the 

 disk-corollas ovate, ciliate. Anthers longer than the filaments. Achenes 

 flattened. Pappus of 2 or 3 scales, or awns. 



1. P. Hysterophorus L, Plants annual. 3-8 dm. tall: leaf -blades oblong to 

 ovate in outline, the segments linear, oblong or ovate: involucres saucer-like, 

 4-5 mm. broad: disk-corollas 1-1.5 mm. long, or slightly more: achenes obo- 

 void, 1.5-2 mm. long. — S. Rare, in fields. Nat. of the s. w. U, S. and Mex. 

 — Sum. 



30. HELIOPSIS L. Perennial, or rarely annual, caulescent, tall herbs. 

 Leaves opposite: blades broadest below the middle, toothed. Heads radiate, 

 solitary or in open corymbs. Involucres campanulate to hemispheric: bracts 

 short, in 2 or 3 series. Receptacle convex or conic, chaffy. Ray-flowers pis- 

 tillate, fruit-producing, enveloped in the bractlets: corollas with a very short 

 tube and a long throat. Achenes 3-4-angled. Pappus a low crown, 1-4 teeth, 

 or wanting. — Sum. — Ox-eye. 



Leaf-blades smooth : pappus wanting, or of 2-4 short teeth. 1. H. helianthoides. 



Leaf-blades rough : pappus crown-like, or of 1-3 sharp teeth. 2. H. scahra. 



1. H, helianthoides (L.) B.S.P. Stem and branches smooth and glabrous or 

 nearly so: leaf -blades thinnish, ovate to lanceolate, 8-20 cm. long, sharply 

 serrate : heads showy, the rounded disk usually over 1 cm. high : involucral 

 bracts inconspicuously pubescent: ligules bright-yellow, 2-4 cm. long: achenes 

 nearly 4 mm. long. — Common, on banks and in meadows. 



2. H. scabra Dunal. Stem and branches scabrous-hispidulous : leaf -blades 

 thick, deltoid to ovate or broadly lanceolate, 5-15 cm. long, serrate: heads very 

 showy, the conic disk 1.5-2 cm. high: involucral bracts cinereous-pubescent: 

 ligules bright-yellow, 2-4 cm. long : achenes nearly 5 mm. long. — M. Occa- 

 sional, in fields and thickets. Nat. of w. N. A. 



31. VEEBESINA L. Annual diffuse herbs. Leaves opposite: blades nar- 

 row, entire or sparingly toothed. Heads small, inconspicuously radiate. Invo- 

 lucres hemispheric or campanulate: bracts broad, those of the outer series 

 scarcely larger than those of the inner. Ray-flowers several: ligules white, in- 

 conspicuous. Disk-flowers several : corollas with a short tube and a longer 



