COMPOSITAB (COMPOSITE FAMILY) 855 



rather sharply serrate; upper stem-leaves se&sile, pinnatifid with remotish seg- 

 ments and rounded sinuses ; inflorescence cyinose-corymbose, many-headed ; 

 heads radiate, 6-8 cm. hiijh during anthesis achenes usually hispidulous along 

 the angles. Va., and south w. May, June. 



lo. S. platt6nsis Nutt. Stems one to several, simple or branched from the 

 base, !.">-<> <lm. high ; !<nr,'r leaves petiolate, ovate to oblong -lanceolate, 6-10 cm. 

 long, 1-2.5 cm. broad, crcnate-dentate to di-cply and irregularly pinnatifid, 

 thirkish nnd as well as the stem usually white-tomentose, more or less glabrate ; 

 inflorescence a corymbose cyme ; heads about 1 cm. high, radiate ; achenes 

 commonly hispidulous. Dry, sandy, or gravelly soil, s. w. Ont. to e. Mont, 

 and Tex. Apr.-July. 



14. S. tomentbsus Michx. (WOOLLY R.) Clothed with scarcely deciduous 

 hoary wool; stems 3-6 dm. high ; basal leaves oblong, 2-15 cm. long, 1-7 cm. 

 broad, obtuse, crenate or entire, often on elongated stout petioles, 2.5 dm. or 

 less in length : the stem-leaves similar, lyrate-pinnatifid to entire; inflorescence 

 cymose-corymbose ; heads radiate ; rays 12-15. N. J. to Fla. and Tex. Apr.- 

 June. 



15. S. antennariifblius Britton. Stem erect, 3-4 dm. high ; leaves mostly 

 basal, oblong-obovate to spatulate, including the petiole 3-6 cm. long, 0.5-1.5 

 cm. broad, rounded or obtuse at the apex, somewhat remotely and shallowly 

 angulate-dentate, narrowed below into the petiole, finely and densely matted- 

 tomentose beneath, loosely floccose-tomentose above; stem-leaves sublyrate or 

 merely dentate, the uppermost reduced to linear entire bracts ; inflorescence 

 cymose-corymbose, few-headed ; heads radiate ; achenes papillose-hirsute along 

 the angles. Blue Ridge, Va. June. 



1(5. S. canus Hook. Usually low, 1.5-3.5 dm. high, persistently tomentose, 

 rarely at all glabrate; lower leaves oblong-oblanceolate or subspatulate, includ- 

 ing the petiole 5-10 cm. long, 1-2 cm. broad, obtuse or rounded at the apex, 

 entire or sparingly toothed, white-tomentose on both surfaces, rarely glabrate 

 above ; stem-leaves entire or slightly pinnatifid, the uppermost becoming sessile 

 and not infrequently clasping the stem by a sub-auriculate base ; inflorescence 

 few-headed ; heads 10-12 mm. high, radiate ; involucre arachnoid-tomentose to 

 nearly glabrous, sparingly calyculate ; ray-flowers commonly 8 ; disk-flowers 

 numerous. Sask., Alb., and along the Rocky Mts. to Col., eastw. to n. Minn, 

 (according to Upham). June Aug. 



17. S. integlrrimus Nutt. Covered when young with long jointed crisp-hir- 

 sute or subvillous hairs, soon more or less glabrate ; lower leaves oblong-lanceo- 

 late or suboblong, including the narrowly winged petiole usually 1-2 dm. long, 

 14 cm. broad, entire or denticulate ; the upper bract-like, attenuate from a 

 broad subclasping base; inflorescence few-headed; heads 10-12 mm. high; in- 

 volucral bracts usually green-tipped. Sask., Man., Dak., la., and westw. May- 

 July. 



18. S. Pseudo-Arnica Less. Loosely white-woolly, sometimes becoming gla- 

 brous ; stem stout, 0.5-10 dm. high, leafy above, often nearly naked below ; 

 leaves oblong-lanceolate to subovate, 0.5-1.5 dm. long, 1-5 cm. broad, repand- 

 dentate to subentire, the lower tapering into a narrow petiole-like base, the 

 upper sessile ; heads 1.5-2 cm. high ; rays 20 or more, yellow. Gravelly beaches, 

 e. Me. to Lab.; and in the Alaskan region. 



80. ARCTIUM L. BURDOCK 



Heads many-flowered ; flowers all tubular, perfect, similar. Involucre globu- 

 lar ; the imbricated bracts coriaceous and appressed at base, attenuate to long 

 stiff points with hooked tips. Receptacle bristly. Achenes oblong, flattened, 

 wrinkled transversely ; pappus short, of numerous rough bristles, separate and 

 deciduous. Coarse biennial weeds, with large unarmed petioled roundish or 

 ovate mostly cordate leaves floccose-tomentose beneath, and small solitary or 

 clustered heads; flowers purple, rarely white. (Name probably from d/jjcros, 

 a bear, from the rough involucre.) 



1. A. LAFPA L. (GREAT B.) Heads subcorymbose, 3-5 cm. broad; invo- 



