COMPOSITiE. 373 



17. SILPHIUM. Linn. ; Endl. ge?i. 2^74. SILPHIUM. 



[ From silpM, the name of a medicinal plant of Africa, transferred to this genus by Linnseus.] 



Heads monoscious, many-flowered ; the ray-flowers numerous, pistillate ; the ligules in a 

 single series, deciduous, but the flat ovaries in 2 — 3 rows : disk-flowers tubular, sterile. 

 Scales of the involucre broad and leafy, appressed at the base, more or less squarrose at 

 the summit ; the innermost ones small and chafTy. Receptacle chaffy. Ligule of the ray- 

 flowers elongated and spreading. Style in the sterile flowers undivided, elongated, hispid. 

 Achenia of the ray broad and flat, winged and emarginated, crowned with two subulate or 

 awned teeth ; those of the ray with an obscure coroniform pappus. — Coarse perennial 

 herbs, mostly rough or hispid, exuding a resinous juice. Leaves various. Heads large, 

 corymbose, panicled or solitary. Flowers yellow. 



1. SiLPHiuM TRiFOLiATUM, Linn. Temote Siljphium. 



Stem very smooth, and often glaucous ; cauline leaves 3-4 in a whorl (the uppermost 

 opposite), lanceolate, acute, remotely denticulate, rough (especially above), on short hispid 

 petioles ; heads loose, corymbose or paniculate ; scales of the involucre smooth, ciliate ; 

 achenia obovate-oval, the broadish wings produced at the summit, and confluent with the 

 subulate teeth. — Linn. sp. 2. p. 290 ; Hook. hot. mag. t. 3355 ; Torr. <^ Gr. fl. N. Am. 2. 

 p. 277. S. trifoliatum, ternatum and atropurpureum, Retz in Willd. sp. 3. p. 2333 ; Pursh, 

 fl. 2. p. 578 ; Ell. sk. 2. p. 466. S. ternatum, and (partly) S. trifoliatum, DC. prodr. 5. 

 ;;. 513. S. tcrnifolium, Mickv. fl. 2. p. 146. 



Stem 4-6 feet high, terete or only slightly angled, striate, commonly purplish. Leaves 

 4-6 inches long and about an inch wide, undivided, varying from narrowly to ovate-lanceolate, 

 sometimes nearly smooth underneath or on both sides ; upper ones usually opposite but 

 .sometimes alternate, sessile. Heads rather small, with 12-18 rays. Awns of the achenia 

 at length separating from the wings. 



Near the Falls of Niagara (Dr. Eddy). August. 



