COMPOSITE. 207 



uncinate, spinulose-toothed, cordate-clasping; heads umbellate-corymbose. 



»S. spinulosus,\a.T. asper Linn. S. spinulosus Big. 



Fields and waste places. Throughout the U. S. Aug., Sept. (1). — Stem 

 about 2 feet high, smooth or slightly hairy. Heads small, somewhat urabelled. 

 Flowers yellow. Introduced from Europe. Spiny-leaved Sovj-thistle. 



3. (S. arvensLS Lvmi. : root creeping ; stem erect, smooth ; leaves runci- 

 nate-pinnatifid, spinulose-toothed, cordate-clasping; the auricles obtuse; 

 panicle umbellate-corymbose ; pedicels and involucres glandular-hispid. 



Near cultivated grounds, Ver. to Penn. Newfoundland Hook. Aug., Sept. 

 %.. — Stem 2 — 3 feet high. Heads as large as in the Dandelion. Flotvers yellow. 

 Introduced from Europe. Large Sow-thistle. 



65. HIERACIUM. Linn.— Usiwk Weed. 



(From the Greek icpa^, a hawk ; because birds of prey were supposed to em 

 ploy this plant to strengthen their powers of vision. Hook. Br. Fl.) 



Heads many-flowered. Involucre ovate or cylindric ; scales 

 linear-obtuse, imbricate, rarely only in two series. Receptacle 

 alveolate or pitted and fimbrillate. Aclienia 5 -sided, somewhat 

 striate, mostly clavate, not beaked. Pappus in a single series 

 of very dense dull- white rigid scabrous hairs. 



* Stem leaf]/. 



1. H. Canadense Mich. : stem erect, simple or sparingly branched above ; 

 leaves sessile, oblong-lanceolate, acute, smboth or somewhat pubescent, 

 acutely and divaricately toothed ; heads corymbose ; involucre smoothish ; 

 outer scales mostly spreading in fruit. H. virgatum, fasciculatum and ma- 

 crophyllum Pursh. H. Kalmii Spreng. not of Linn, (accordincr to Tmr. 

 4' Gr.) 



Rocky woods. Can. N. Eng. and N. Y. N. to lat. 66°. W. to Oregon. July, 

 Aug. %. — Stem stout, smooth, pubescent or hairy. Heads axillary and termi- 

 nal, on downy or hispid peduncles. Flowers pale-yellow. 



Canadian Hawk-weed. 



2. H. scahrum- Mich. : stem erect, stout, hispid below, rough above ; 

 leaves obovate or oval, entire or somewhat denticulate, hairy, the lower 

 narrowed at the base, the upper closely sessile ; peduncles and involucre 

 hispid and downy. H. viarianum Willd. H. Gronovii^p.Hook. 



Woods. Can. to Geor. W. to Miss. July, Aug. %. — Stem about 2 feet 

 high, often very rough below. Heads numerous, in a fastigiate corynib. Flow- 

 ers yellow. Rough Hawk-weed. 



3. H. Gronmni Linn. : stem erect, leafless and paniculate above '; leaves 

 entire or denticulate, pale, sparingly villous-hirsute ; the lower oblong-obo- 

 vate or spatulate ; upper oval or oblong, sessile or clasping ; peduncles and 

 involucre glandular-hispid. 



Dry woods. Can. to Flor. W. to Texas. July, Aug. %. — Stem about 2 

 feet high, nearly naked. Heads in a long naked panicle. Flowers yellow. 

 Differs from the preceding in its more slender, nearly naked stem and much 

 longer pedimcles. Gronovius's Hawk-weed. 



4. H. paniciUatum Willd. : stem erect, loosely paniculate, smooth above^ 



