SiLPHiuM. COMPOSITE. 373 



17. SILPHIUM. Linn. ; Endl gen. 2^74. SILPBIVM. 



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



Heads monoecious, 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 chaffy. 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 jjappus. — Coarse perennial 

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

 corjrmbose, panicled or solitary. Flowers yellow. 



1. SiLPHiuM TRiFOLiATUM, Linn. Temate Silphium. 



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 broad ish 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. sjj. 3. p. 2333 ; Pursh, 

 fl. 2. p. 578 ; EH. sk. 2. p. 46(5. S. ternatum, and (partly) S. trifoliatum, DC. prodr. 5. 

 p. 513. S. ternifolium, Michx. fl. 2. p. 146. 



Stem 4-6 feet high, terete or only slightly angled, striate, conr)monly 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. 



