CAKDUACEAE 1247 



blades, the upper with oblong-lanceolate or ovate sessile blades : heads few, showy : invo- 

 lucres campanulate, 1-2 cm. high ; bracts linear-lanceolate or lanceolate to ovate or oblong, 

 ciliate and with a few stalked glands on the margins, the outer acute, the inner obtuse : ray- 

 flowers 4-5 ; ligules bright yellow, 1.5 cm. long : achenes obovate, 6-7 mm. long, with the 

 wing prolonged in 2 horn-like teeth. 

 In open woods and sandy soil, Texas. 



75. ENGELMANNIA T. & G. 



Perennial caulescent herbs, with pubescent foliage. Leaves alternate : blades pinnatifid, 

 the segments often toothed. Heads radiate, peduncled. Involucres hemispheric or cam- 

 panulate : bracts in 2-3 series, the outer narrow, the inner broader, and subtending the 

 ray-flowers. Receptacle flat, chaffy. Ray-flowers 8-10, pistillate, fruit-producing. Disk- 

 flowers several, perfect, not fruit-producing, partly embraced by the bractlets. Anthers 

 minutely 2-toothed at the base. Achenes flat, broadened upward, 1-ribbed on each face. 

 Pappus an irregular persistent crown. 



1. Engelmannia pinnatifida T. & G. Roots stout. Stems 3-7 dm. tall, hirsute or 

 hispid, more or less widely branched above : leaf -blades 3-15 cm. long, deeply pinnatifid, 

 the lower ones long-petioled, the upper sessile : heads showy : involucres 7-8 mm. high ; 

 bracts various, the outer linear, those of the second series with suborbicular bodies and 

 linear tips, those of the inner series oval or obovate, short-tipped, all ciliate, obtuse : ray- 

 flowers 8-10 ; ligules golden yellow, about 1 cm. long : achenes oblong-ovate, 4 mm. long, 

 ciliate. 



On prairies or open hillsides, Kansas to Arkansas, Louisiana and Arizona. Spring. 



76. PARTHENIUM L. 



Perennial or sometimes annual caulescent herbs, or shrubs. Leaves alternate : blades 

 toothed, pinnatifid or dissected. Heads radiate, but not conspicuous. Involucres hemis- 

 pheric, campanulate or flat, peduncled : bracts in 2-3 series, appressed, obtuse. Recep- 

 tacle convex or conic, chaffy. Ray-flowers usually 5, pistillate, fruit-producing : ligules 

 broad but very short, white or whitish. Disk-flowers perfect, not fruit-producing, embraced 

 by the bractlets. Anthers entire at the base. Achenes, flattened, margined, keeled on the 

 inner face, tipped with the persistent ray-flower. Pappus of 2-3 scales or awns. 



Leaf-blades 1-2-pinnatifid : heads not firm at maturity. 



Leaf-blades pinnately parted, the segments pinnatifid or toothed. 1. P. Hysterophorus. 



Leaf-blades lyrately pinnatifid. 2. P. lyratum. 



Leaf-blades merely toothed : heads very firm at maturity. 3. P. integrifolium. 



1. Parthenium Hysterdphorus L. Annual, strigose or sometimes slightly hirsute. 

 Stems 3-7 dm. tall, more or less diffusely branched : leaf-blades oblong to ovate in outline, 

 1-2-pinnately parted, the segments lanceolate to linear, pinnatifid or toothed : heads nu- 

 merous : involucres saucer-like, 4-5 mm. broad ; bracts concave, the outer rhombic or 

 elliptic-rhombic, the inner broader, cuneate at the base : ray-flowers few ; ligules whitish, 

 reniform, less than 1 mm. broad : disk-corollas 1-1.5 mm. long : achenes obovate, 1-1.5 

 mm. long. 



In sandy soil and waste places, Florida and Alabama to Texas. Also in tropical America. 



2. Parthenium lyratum A. Gray. Perennial, canescent or somewhat hirsute. Stems 

 1-4 dm. tall, solitary or tufted, branching above : leaf-blades ovate, suborbicular or ob- 

 ovate in outline, palmately lobed or lyrately pinnatifid, 1-3 cm. long, the lower ones long- 

 petioled : heads numerous : involucres flattish, 5-6 mm. broad ; bracts various, the outer 

 ovalj obtuse, the inner broader than high, notched at the apex, truncate at the base : ray- 

 flowers few ; ligules cup-like, about 1 mm. long : disk-corollas 2-2.5 mm. long : achenes 

 obovate or rhombic-obovate, 3 mm. long, with 2 ovate teeth at the top. 



In dry soil, Texas. Spring to fall. 



3. Parthenium integrifolium L. Perennial, scabrous-pubescent. Stem 4-12 dm. 

 tall, sometimes clustered, corymbose above : leaf-blades 1-3 dm. long, various, those of the 

 basal and lower stem-leaves oblong or lanceolate, long-petioled ; the upper stem-leaves 

 elliptic, oblong ovate or oval, sessile, all acute, singly to triply dentate or crenate-dentate : 

 heads several or numerous, often crowded : involucres campanulate, becoming globular, 

 4-6 mm. high ; bracts oblong, ovate or suborbicular, obtuse : ray-flowers few ; ligules white 

 or cream-colored, cornucopia-like, 2 mm. broad, retuse : disk-corollas 2.5 mm. long: 

 achenes 3.5-4 mm. long. 



In dry or stony soil, Maryland to Minnesota, Georgia and Texas. Spring and summer. 



