236 ELEMENTS OF BOTANY. 



Rays white or purplish. 

 Receptacle naked. 

 Disk flowers tubular. 

 Bracts imbricated in several rows . VI. Aster. 



Bracts only slightly imbricated . VII. Erigeron. 



Disk flowers bilabiate . . . XVII. Thyrsanthema. 

 Receptacle chaffy XIV. Achillea. 



I. ELEPHANTOPUS. 



Perennial herbs ; stem scape-like, corymbosely branched 

 above ; leaves mostly basal and nearly entire ; heads small, 

 in dense, bracted clusters, discoid, 3-5-fiowered ; involucre 

 oblong, its bracts about 8, in 2 series, the outer shorter ; 

 receptacle naked ; corollas all alike, deeply 5-lobed, deeply 

 cleft on one side, purple ; achenes oblong, ribbed, hairy; 

 pappus of rigid, awn-like scales or bristles which are dilated 

 at the base. 



1. E. Carolinianus Willd. Carolina Elephant's Foot. 

 Stem erect, hairy, leafy, 1-2 ft. high ; leaves oval to obovate, obtuse 

 at the apex, narrowed below into a winged petiole, serrate or den- 

 tate, the upper often sessile ; bracts 3-5, ovate, longer than the 

 heads; invohicral bracts slightly hairy; achenes hairy, 10-ribbed. 

 June-September. In damp, shady places. 



2. E. TOMENTOsus L. WooLLY Elephant's FooT. Stem erect. 

 rough-hairy, nearly leafless, 1-2 ft. high; leaves mostly basal, obo- 

 vate-oblong, on a margined petiole, crenate, soft-pubescent beneath, 

 stem leaves 1 or 2, small, sessile ; bracts ovate to cordate, shorter 

 than the heads, involucral bracts very hairy ; achenes nearly smooth, 

 10-ribbed. June-August. In damp soil. 



II. EUPATORIUM. 



Perennial herbs ; stems leafy ; leaves opposite, verticillate 

 or sometimes alternate, often resinous-dotted ; heads discoid, 

 .3-many-flowered, in cymes or panicles ; involucre cylindrical 

 or spreading, its bracts imbricated in 2 or more series ; recep- 

 tacle naked ; flowers white, blue or purple ; corolla slender ; 

 achenes 5-angled, truncate, smooth ; pappus a single row of 

 roudi bristles. 



