248 COMPOSURE, (composite family.) 



perennial herbs, viscid-hairy, exhaling a heavy odor. Leaves large and thin, 

 opposite, or the uppermost alternate, lobed, and with dilated appendages like 

 stipules at the base. Heads in panicled corymbs. Elowers light yellow ; in 

 summer and autumn. (Dedicated to the Muse, Polyhymnia, for no obvious 

 reason, as the plants are coarse and inelegant. ) 



1. P. Canadensis, L. Clammy-hairy; lower leaves deeply pinnatifid, the 

 uppermost triangular-ovate and 3-5-lobed or angled, petioled; heads small; 

 ratjsfeic, olovate or wedge-form, shorter than the involucre, whitish-yellow. — Moist 

 shaded ravines, W. New York (and "Weehawken, New Jersey, Dr. Allen) to 

 Penn., Wisconsin, and southward along the mountains. — Var. discoidea has 

 the corolla of the ray-flowers reduced to a mere ring around the base of the style. 

 Mt. Carroll, Illinois, Henry Shimer. 



2. P. Uvedilia, L. Eoughish-hairy, stout {i°-10° high); leaves broadly 

 ovate, angled and toothed, nearly sessile ; the lower palmately lobed, abruptly 

 narrowed into a winged petiole; outer involucral scales very large; rays 10-15, 

 Vmear-oblong , much longer than tile inner scales of the involucre, yellow. — Rich soil, 

 W. New York to Illinois and southward. 



26. CHRYSOGOIflTM, L. Chktsogonum. 



Heads many-flowered, radiate ; the rays about 5, pistillate and fertile ; the 

 disk-flowers perfect but sterile. Involucre of about 5 exterior leaf-like oblong 

 scales, which exceed the disk, and as many interior shorter and chaff-like con- 

 cave scales. Receptacle flat, with a linear chaff to each disk-flower. Achenia 

 all in the ray, obovate, obcompressed, 4-angled, each one partly enclosed by the 

 short scale of the involucre behind it ; those of the disk-flowers abortive. Pap- 

 pus a small chaffy crown, 2 - 3-toothed, and split down the inner side. — A low 

 (2' -6' high), hairy, perennial herb, nearly stemless when it begins to flower, 

 the flowerless shoots forming runners. Leaves opposite, ovate or spatulate, cre- 

 nate, long-petioled. Heads single, long-peduncled. Flowers yellow. (Name 

 composed of xpi'fofi golden, and ydi/u, knee.) 



1. C. Virgini&num, L. Dry soil, from Pennsylvania (Mercersburg, 

 Prof. Porter) and Illinois southward. May - Aug. — Rays ^' long. 



27. StLPHIUM, L. Rosin-Plant. 



Heads many-flowered, radiate ; the rays numerous, pistillate and fertile, their 

 broad flat ovaries imbricated in 2 or .3 rows ; the disk-flowers apparently perfect, 

 but with undivided style, and sterile. Scales of the broad and fiattish involu- 

 cre imbricated in several rows, broad and with loose leaf-like summits, except 

 the innermost, which are small and resemble the linear chaff of the flat recep- 

 tacle. Achenia broad and flat, obcompressed, sun"ounded by a wing which is 

 notched at the top, destitute of pappus, or with 2 teeth confluent with the 

 winged margin : achenia of the disk sterile and stalk-like. — Coarse and tall 

 rough perennial herhs, with a copious resinous juice, and large corymbose- 

 paniclcd yellow-flowered heads. (SiX^iok, the ancient name of a plant which 

 produced some gum-resin, perhaps assafoetida, was transferred by Linnaeus to 

 this American genus.) 



