SILPHIUM. LXXV. COMPOSITE. 335 



serted ; receptacle naked ; pappus capillary. Shrubby plants, with 

 alternate leaves and white flowers. 



B. HALIMIFOLIA. Groundsel Tree. 



Shrubby; Ivs. obovate, incisely dentate above, the highest ones lanceo- 

 late ; panicle compound, leafy ; fascicles pedunculate. This is almost the only 

 arborescent plant of this order found in the Northern States. It is 6 12f high, 

 growing on sea-coast and river alluvion. Every part is covered with white 

 dust. The fertile heads growing upon separate plants are in large, loose, ter- 

 minal panicles, and furnished with very long, slender pappus. Corollas white. 

 Sept. The beauty of this shrub entitles it to cultivation. 



TRIBE 4. SENECIONIDEJE. 



Heads radiate or discoid. Branches of the style linear, hairy or hispid at 

 the apex, which is either truncated or produced into a conical or elongated ap- 

 pendage. Leaves opposite or alternate. 



Section 1. Heads radiate. 



25. ARNICA. 



Involucre of equal, lanceolate scales, I or 2 rowed; ray-flowers 9, 

 disk?; receptacle flat, with scattered hairs ; pappus single, rigid and 

 serrulate. % St. simple. Lvs. opposite. Fls. yellow. 

 A. MOLLIS. 



St. pubescent, erect ; Ivs. pubescent, becoming nearly glabrous, thin, veiny, 

 dentate, ovate-lanceolate and oblong; radical ones stalked, cauline sessile; 

 hds. few ; invol. hairy, with acuminate scales ; ach. hairy. An alpine plant 

 found in ravines on the White Mts., and also, according to Torrey <$ Gray, on 

 the Mts. in Essex Co., N. Y. Stem 1 2f high, with several pairs of sessile 

 leaves, and 1 5 yellow heads of middle size. Leaves 25 inches in length, 

 the upper ones broad at the base, the lower tapering to a winged petiole, often 

 acute but not acuminate. 



26. POLYMNIA. 



The name of one of the ancient Muses ; why applied to this plant is not obvious. 



Involucre double, outer of 4 or 5 large, leafy scales, inner of 10 

 leaflets, concave ; ray-flowers pistillate, few ; disk sterile ; receptacle 

 chaffy ; pappus none. % Clammy herbs. Lvs. opposite. Fls. yellow. 



1. P. CANADENSIS. Leaf-cup. 



Viscid- villous; ITS. denticulate, petiolate, acuminate, lower pinnatifid, up- 

 per 3-lobed or entire. A coarse, broad-leaved, hairy-viscid plant, 3 5f high, 

 Niagara Falls ! Stem with opposite leaves and spreading branches. Flowers 

 light-yellow, the rays short, surrounded by the concave leaflets of the double 

 calyx in such a manner as to form a sort of cup, hence called leaf-cup. Leaves 

 feather-veined, 3 8' long, and nearly as wide, lobes deeply divided and acu- 

 minate. Heads i' diam. June. 



2. P. UVEDALIA. Yellow Leaf-cup. 



Lvs. opposite, 3-lobed, acute, decurrent into the petiole, lobes sinuate- 

 angled; rays elongated. In highland woods. Stem 3 6f high. Lower leaves 

 very large. Flowers large, yellow, the rays much longer than the involucre. 

 July. Neither of these plants has been found in N. Eng., and they are rare in 

 N. Y., but not uncommon in the Western States ! 



27. SILPHIUM. 



Heads many-flowered ; ray-flowers numerous, in 2 or 3 rows, fer- 

 tile, outer row ligulate ; disk flowers sterile ; involucre campanulate, 

 scales in several series, leafy and spreading at summit ; receptacle 

 small, flat, chaffy ; achenia broad, flat, obcompressed, crowned with a 



