336 LXXV. COMPOSITiE. Parthenium. 



2-toothed pappus. — % Stout^ coarse, resinous herbs. Hds. large. Fls. 

 yellow. 



1. S. LACiNiATUM. Rosliv-wced. Polar Plant. 



Very rough, with white, hispid hairs ; Ivs. alternate, pinnately parted, 

 lower petiolate, segments sinuate-lobed or entire ; hds. spicate, distant ; scales 

 of involucre ovate, appendaged and squarrose at apex. — Western States! to 

 Tex., producing columns of smoke in the burning prairies by its copious resin. 

 Stem 3 — lOf high. Lower leaves 1 — 2f long, much divided, resembling those 

 of some thistles. Heads 4 — 8, very large, with large, yellow rays. Jl. — Sept. 



2. S. TEREBiNTHiNACEDM. Prairie Burdock. 



St. and pcd. glabrous ; Ivs. mostly radical, ovate and ovate-oblong, cor- 

 date, dentate-serrate, obtuse, scabrous, on long petioles ; Ms. few, paniculate ; 

 scales roundish and oval, glabrous. — Prairies, Western ! and Southern States. 

 Plant exuding resin. Stem 4 — 8f high, nearly naked and simple. Leaves 

 erect, .scabrous, rigid, 1 — 2f long, 7 — 16' wide. Involucre globose. Rays 15— 

 25, 1' long. Achenia narrowly 2- winged. July — Sept. 



/3. pinnatijidum. T. & G. (S. pinnatifidum. Ell.) Dvs. more or less deeply 

 lobed or pinnatifid. 



3. S. TRiFOLiATUM. Temate-leavcd Silphium. 



St. glabrous and often glaucous, terete or 6-sided ; cauline Ivs. lanceolate, 

 acute, scabrous above, smooth below, remotely dentate, on very short petioles, 

 verticillate in 3s or 4s ; upper ones opposite; hds. loosely cymose, on rather 

 long peduncles ; scoJes broadly ovate, rather obtuse, smooth ; CLch. oval, with 2 

 short teeth. — Dry woods and prairies, Ohio, Sullivant ! and Southern States. 

 Stem 4 — 6f high. — Leaves 4 — 6' by 1 — 2", Rays 12 — 16, expanding about 2^'. 



4. S. IXTEGRIFOLIUM. Michx. 



Scabrous ; 5/. quadrangular, striate, simple ; Ivs. opposite, sessile, ovate- 

 lanceolate, entire or slightly dentate; hds. in a close corymb; scales squarrose; 

 ach. roundish, broadly winged, with 2 long teeth. — Western States ! S. to Ga. 

 Stem very rigid, 3 — 7f high. Leaves rigid, broad and clasping at ba.se, 3 — 6' 

 long, i as wide, rather variable in form. Heads middle-size. Rays 12-— 20, 1' 

 in length. Achenia twice as large as in the preceding species. July, Aug. 



i3. tcrnatum. Wood. ^S"^. 6-sicled ; Ivs. ternately verticillate. — Prairies ! with 

 the common form ; apparently connecting this with S. trifoliatum, from which 

 it is nevertheless quite distinct in habit. 



5. S. PERFOLiATUM (and S. connatum. Linn.) Cup-plant. 



St. square ; Ivs. large, thin, opposite, connate-perfoliate, ovate, coarsely 

 toothed, narrowed towards the base; hds. in a trichotoraous c}Tne, the central 

 on a long peduncle ; scales ovate, obtuse, squarrose ; ach. broadly obovate, winged, 

 emarginate. — Along streams, &c., Mich. ! to Tenn. A coarse, unattractive 

 plant, quite distinct, although variable. Stem 4 — 7f high. Leaves 8 — 14' by 

 4 — 7', the upper pairs forming a cup with their connate bases. Heads large, 

 with 15 — 25 ravs. 



28. PARTHENIUM. 



Gr. nap^evog, a virgin ; from its medicinal efficacy. 



Heads many-flowered ; ray-flowers 5, somewhat ligulate, fertile ; 

 disk-flowers tubular, sterile : inyolucre hemispherical ; scales in 2 

 series, outer ovate, inner orbicular ; receptacle conical, chafiy ; ache- 

 nia 5, compressed, cohering with 2 contiguous paleas. — American herbs 

 with alternate leaves. 



P. INTEGRIFOLIUM. 



St. pubescent, striate, erect; Ivs. hispid-scabrous, lance-ovate, coarsely 

 dentate-crenate, coriaceous, lower petiolate, upper sessile; hds. many, tomen- 

 tose, cor3^mbed. — % Dry soiis, Middle and Western States ! Stem rigid, 3— 5f 

 high. Radical petioles If long. Leaves 4^12' long, J as wide. Heads white, 

 with 5 very short, cucullate, white rays. July — Sept. 



