1164 CARDUACEAE 



what squarrose, the inner azure : corolla purplish blue or reddish : achenes 2 mm. long, 

 glabrous or nearly so, wing-angled. \_Eupatorium ivaefoliitm L. ] 



In old fields, Mississippi to Texas and Mexico. Also in tropical America. Fall. 



2. Osmia heteroclina (Griseb. ) Small. Minutely pubescent. Stems 5-10 dm. 

 tall, branching : leaf-blades ovate-lanceolate to deltoid-ovate, 2-3 cm. long, rather obtuse, 

 serrate, cuneate to truncate at the base : involucres cylindric, 8-12 mm. long, 20-25-flow- 

 ered ; bracts ovate to oblong, obtuse, appressed, shining, faintly ridged : corolla blue or 

 purplish: achenes 3-3.5 mm. long, nearly glabrous. \_Eupatormm Ae/e)'oc/mt<m Griseb. ] 



In sand, Florida Keys. Also in Jamaica. 



3. Osmia conyzoides (Vahl) Small. More or less densely pubescent. Stems 6-18 

 dm. tall, much branched : leaf-blades ovate to lanceolate, 4-10 cm. long, acuminate, nearly 

 entire or coarsely serrate, commonly cuneate at the base : involucres cylindric, 8-10 mm. 

 high, 12-30-flowered ; bracts ovate to oblong or linear-oblong, 5-7-ridged, the outer ob- 

 tuse, the inner often acute : corollas white or pale blue : achenes 3.5-4 mm. long-, nearly 

 glabrous, sharply angled. \_Eupaiorium conyzoides Vahl.] 



In sand, Florida to Texas. Also in tropical America. 



10. EUPATORIUM L. 



Annual or (all within our range) perennial caulescent herbs or shrubby plants, none 

 vines. Leaves alternate, opposite or sometimes whorled : blades various, entire, toothed 

 or dissected. Heads usually in corymbs. Involucres mostly narrow : bracts scarious to 

 membranous, or herbaceous in one series or several, rarely inconspicuously ribbed. Re- 

 ceptacle flat, naked. Corollas regular, white to purple. Anthers appendaged at the apex, 

 obtuse at the base. Stigmas elongated, obtuse, flattened or thickened above. ' Achenes 5- 

 angled, truncate. Pappus of numerous hair-like bristles in 1 series. 



Leaf-blades mainly dissected into filiform or narrow segments or sometimes deeply pinnatifld. 



Leaf-segments filiform. 'l. E. capillifolmm. 



Leaf-segments linear, linear-filiform or narrowly lanceolate. 

 Leaf-blades 1-2-parted. 



Inflorescence paniculate or thyrsoid : 



Heads 3-6-flo\vered : not glomerate on the inflorescence-branches : 



bracts of the involucre punctate and viscid. 2. E. compositifolium. 



Heads 6-9-flowered : glomerate or clustered at the ends of the inflor- 

 escence branches : bracts of the involucre neither punctate nor 

 viscid. 

 Inflorescence corymbose. 

 Leaf-blades mainly pectinately pinnatifld. 

 Leaf-blades merely toothed or incised. 



Leaves opposite or alternate, or rarely in 3's in 1 or 2 narrow-leaved species. 

 Leaf-blades manifestly petioled. 



Larger leaf-blades fully twice as long as broad. 

 Larger leaf-blades but little longer than broad. 

 Heads .'j-flowered. 

 Heads 10-30-flowered. 



Shrubby perennial plants. 



Leaf-blades entire or merely repand : involucres 3-1 mm. high. 

 Leaf-blades coarsely toothed : involucres 4-5 mm. high. 

 Herbaceous perennial plants. 

 Corolla wholly glabrous. 

 Corolla with persistently bearded lobes. 

 Leaf-blades acuminate. 

 Leaf-blades obtuse or abruptly acute. 

 Leaf-blades sessile or essentially so, or connate-perfoliate. 



A. Leaf-blades neither connate-perfoliate nor connate-clasping. 



Base of the leaf-blade not broader than the rest of the blade or gradu- 

 ally narrowed. 

 Bracts of the involucre obtuse. 



Leaf-blades linear, entire or shallowly and irregularlyltoothed. 

 Leaf-blades less than 1 mm. wide in their normally involute 



condition. 13. E. lecheaefoUurn,. 



Leaf-blades over 2 mm. wide, flat. 14. E. hyssopifolium. 



Leaf-blades lanceolate, oblong, ovate or oval, markedly toothed, 

 except in E. tortifolium. 

 Lower leaf-blades broadest below the middle or about at the 

 middle. 

 Upper leaf-blades toothed from near the base to the apex. 

 . Leaf-blades shallowly and irregularly toothed. 



Leaves spreading : involucres over 4 mm. high. 15. E. Torreyanum. 



Leaves refie-xed : involucres less than 4 mm. high. 16. E. recurvans. 

 Leaf-blades deeply and regularly toothed. 17. E. anomalnm. 



Upper leaf-blades toothed above the middle. 



Involucres 3-1 mm. high, less than 2 mm. thick. 

 Stem glabrous, except sometimes near the inflores- 

 cence: involucres 3 mm. high. 18. E. lancifolium. 



