40S 



COMPOSITAE. 



[Vol. III. 



5. Silphium laciniatum L. Com- 

 pass-plant. Pilot- weed. 

 (Fig. 3869.) 



Silphium laciniatum L. Sp. PI. 919. 1753. 



Rough or hispid, very resinous; stem 

 6-i2 high; basal leaves pinuatifid or bi- 

 pinnatifid, long-petioled, i long or more, 

 the lobes oblong or lanceolate; stem leaves 

 alternate, vertical, their edges tending to 

 point north and south, sessile, or the lower 

 short-petioled, the upper cordate-clasping 

 at the base, gradually smaller and less 

 divided; heads several or numerous, ses- 

 sile or short-peduncled, 2 / -5 / broad, the 

 peduncles bracted at the base; rays 20-30, 

 i / -2 / long; involucre nearly hemispheric, 

 its bracts large, rigid, lanceolate or ovate, 

 very squarrose; achenes oval, about 6 /A 

 long, the wing broader above than below, 

 notched at the apex, awnless. 



On prairies, Ohio to South Dakota, south to- 

 Alabama, Louisiana and Texas. Called also- 

 Turpentine-weed, Polar-plant, Rosin-weed. 

 July-Sept. 



6. Silphium terebinthinaceum 



Jacq. Prairie Dock. Prairie 



Burdock. (Fig. 3870.) 



Silphium terebinthinaceum Jacq. Hort. 

 Vind. x: pi. 43. 1770. 



Stem glabrous or nearly so, branched 

 and scaly above, 4-io high. Leaves 

 all basal or nearly so, coriaceous, ovate, 

 mostly long-petioled, acute at the apex, 

 cordate at the base, rough on both sides, 

 often 12' long and 6 / wide, sharply den- 

 tate; heads numerous, i}4 / -3 / broad, 

 borne on glabrous peduncles; involucre 

 hemispheric, its bracts ovate-oblong, 

 erect, glabrous or minutely pubescent; 

 rays 12-20; achenes obovate, narrowly 

 winged, slightly 2-toothed and emargin- 

 ate at the apex. 



On prairies and in dry woods, southern 

 Ontario and Ohio to Minnesota, south to 

 Georgia, Iowa and Louisiana. Called also 

 Rosin-plant. July-Sept. 



Silphium terebinthinaceum pinnatifidum (Ell.) 



A. Gray, Man. 220. 1848. 

 5. pinnatifidum Ell. Bot. S. C. & Ga. 2: 462. 



1824. 



Leaves laciniate or pinnatifid. Ohio to 

 Georgia. 



51. CHRYSOGONUM L,. Sp. PI. 920. 1753. 



Pubescent perennial herbs, with opposite and basal petioled leaves, and sleuder-peduncled- 

 axillary and terminal, rather large heads of both tubular and radiate, yellow flowers. In 

 volucre hemispheric, its bracts in 2 series of 5, the outer large, obovate or spatulate, folia- 

 ceous, the inner oval, firm, each subtending a pistillate ray-flower. Receptacle chaffy, each 

 scale subtending and partly enclosing a perfect but sterile tubular flower with a 5-toothed 

 corolla. Anthers nearly entire at the base. Achenes obovate, compressed, their margins- 

 acute, not winged, i-nerved on the back, 1-2-ribbed on the inner side. Pappus a short half- 

 cup-shaped crown. [Greek, golden-knee.] 



A monot3'pic genus of eastern North America. 



