840 CARDUACEAE 



Tribe 10. SENECIONEAE. 



Plants scapiferous, dioecious or nearly so, with large basal leaves appearing after flower- 

 ing ; hermaphrodite floAvers usually sterile. 124. Petasites, 

 Plants not scapiferoxis; not dioecious; disk-flowers hermaphrodite, fertile. 

 Involucres of many or several bracts. 



Involucres lax, of commonly much overlapping or unequal bracts. 

 Low annual herbs, with alternate leaves. 



Heads discoid; receptacle flat; corollas with very short tube. 



126. PSATYROTES. 



Heads radiate; receptacle conical; disk-flowers with long tube. 



125. CROCIDIUM. 



Suffrutescent perennial, with opposite leaves; heads radiate. 



127. Haploestes. 

 Involucres of connivent erect herbaceous equal bracts, with or without smaller 



calyculate ones below. 



Leaves mostly opposite; pappus of a single sorit^.s of riprid bristles. 



128. Arnica. 



Leaves alternate; pappus of numerous soft bristles. 129. Sexecio. 

 Involucres of 4-6 firm concave erect and stronglj^ overlappmg bracts; slirubs with 

 alternate leaves and discoid heads. • 130. Tetradymia. 



Tribe 11. CYNAREAE. 



Achenes attached by the very base; flowers all alike oi nearly so; hermaphrodite. 

 Leaves not prickly; filaments glabrous: style-branches slender, free. 



Involucre globose; bracts subulate, spine- or awn-hke, spreading, hooked at the 



tip. 131. Arctium, 



Involucre oblong or obovoid; bracts appressed, muticous. 



132. Sat'ssttrea. 

 Leaves more or less prickly; filaments bearded or papillose, rarely glabrous; style- 

 branches more o* less united into a cylindi'ical body with a hair-ring below. 

 Receptacle densely bristly; nappus plumose. 133. ClRSlXJTSl, 



Receptacle deeply honeycombed, scarcely bristly; pappus not plimiose. 



. , 134. Onopordox. 



Achenes obliquely attached by one side; marginal flowers usually neutral, with enlargett 

 obUque corollas. 135. Centaurea. 



1. VERNONIA Schreb. Iron-weed. 



Coarse erect perennial herbs/with alternate leaves and corymbose-paniculate^ 

 purple or rose-colored, or rarely white flowers. Involucre hemispherical to 

 oblong-cylindric or turbinate; its bracts imbricate in several or many series, dry 

 or partly herbaceous. Receptacle flat, naked. Ray-flowers none. Corollas 

 regular, 5-cleft, with narrow lobes. Anthers sagittate at the base, but not cau- 

 date. Achenes 8-10-ribbed, truncate at the apex, callous at the base. Pappus 

 in two series in our species, the outer of small squamellae or short stout bristles,. 

 the inner of capillary scabrous bristles. 



Leaves ovate-lanceolate, piimately veined; bracts obtuse or acute. 1. V. corymbosa. 



Leaves linear or lance-linear; lateral veins indistinct; bracts short-acuminate. 



2. V. marginata. 



1. V. corymbosa Schwein. Stem glabrous, usually red, 4r-8 dm. high; 

 leaves sessile, ovate-lanceolate, 4^7 cm. long, acute, regularly serrate, scabrous 

 above, glabrous and pitted beneath; heads corjTnbose, 8-12 mm. high, about 

 21-flowered- involucre campanulate or hemispheric; bracts purple, appressed; 

 achenes glabrous or nearly so. 7. fasciculala Coult.. not Michx. Valleys: Man. 

 — Neb.— N.D. Plain, Au. 



« 1 



'k 



2. V. margmata (Torr.) Raf. Stem glabroxis or nearly so, 4-8 dm. high; 

 leaves Unear or linear-Lanceolate, 5-15 cm. long, entire or minutely serrulate, 

 punctate on both sides, puberulent above; heads in a flat-topped corymb, about 

 1 cm. high; bracts purple, ovate or lance-ovate; achenes glabrous. V. Jamisii 

 T. & G. Plains: Neb.— Okla.— Tex.— Colo. Plain, Au. 



2. HOFMEISTERIA Walp. 



Low suffrutescent plants, with incised leaves and long-peduncled heads with 

 white flowers. Involucre campanulate or hemispherical, its bracts imbricate in 

 several series, striate-nerved. Receptacle naked. Ray-flowers none. Corollas 

 of disk-flowers regular, 5-cleft. Anthers not caudate at the base. Style-branches 

 clavate, stigmatose only at the base. Achenes 5-ans:led, not caudate, but with 



