COMPOSITAB (COMPOSITE FAMILY) 855 



rather sharply serrate; upper stem-leaves sessile, pinnatifid with remotish seg- 

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

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

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



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

 base, 1.5-6 dm. high ; lower leaves petiolate, ovate to oblong-lanceolate, 5-10 cm. 

 long, 1-2.5 cm. broad, crenate-dentate to deeply and irregularly pinnatifid, 

 thickish and as well as the stem usually white-tomentose, more or less glabrate ; 

 inflorescence a corymbose cyme ; heads about I 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. 



16. 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. integSrrimus 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, 

 1-4 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 tfp/cros, 

 a bear, from the rough involucre.) 



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



