Genus 95.] 



THISTLE FAMILY. 



481 



Senecio aureus gracilis ( Pursh ) Britton. 

 Senecio gracilis Pursh, Fl. Am. Sept. 529. 1814. 



Stem slender. i°-2° high, the lowest axils some- 

 times woolly. Basal leaves smaller than those of the 

 type, cordate or subcordate; heads numerous, rather 

 small; rays conspicuous. In wet soil, Rhode Island 

 to Michigan, South Dakota, Virginia and Missouri. 



16. Senecio Douglasii DC. Douglas' 

 Senecio. (Fig. 4048.) 



Senecio Douglasii DC. Prodr. 6: 429. 1837. 



Woody at the base, usually branched, some- 

 times shrubby, glabrous or tomentose, leafy, 

 I°-6° high. Leaves sessile, or the lowest peti- 

 oled, mostly thick, i'-3' long, pinnately parted 

 into 3-9 linear or filiform entire segments, or the 

 upper, or sometimes all of them, linear and en- 

 tire; heads corymbose at the ends of the branches, 

 %'-i' broad, slender peduncled; involucre cyl- 

 indric or becoming campanulate, 4"-6" high, 

 its bracts linear, acute or acuminate, usually 

 with some subulate exterior ones; rays S-15; 

 achenes canescent; pappus bright white. 



Plains, in drj'.soil, Nebraska to Texas and Mexico, 

 west to California. June-Sept. 



17. Senecio palustris (L. ) Hook. Marsh Fleawort. Pale Ragwort. 



Marsh Groundsel. (Fig. 4049.) 



Cineraria paluslris L. Sp. PI. Ed. 2, 243. 1763. 

 Senecio paluslris Hook. FI. Bor. Am. 1:334. 1833. 



Annual or biennial, pubescent or glabrate; 

 stem stout, simple, hollow, (>'-2\' high. Leaves 

 lanceolate, oblong or spatulate, entire, dentate, 

 or laciniate, acute or obtuse, i'--]' long, 3"-i5" 

 wide, or the upper linear-lanceolate and small, 

 those of the stem sessile and somewhat auricu- 

 late-clasping, the basal petioled; heads numer- 

 ous, 6"-i2" broad, mostly short-peduncled in a 

 large, rather dense, terminal corymb; involucre 

 cylindric, becoming campanulate, 3"-4" high, 

 its bracts linear, acute, more or less pubescent, 

 with no shorter outer ones; rays 15-20, pale-yel- 

 low; achenes glabrous; pappus white, elongated, 

 at length twice the length of the involucre. 



In swamps, Iowa and Wisconsin to Manitoba and 

 arctic America, west to Alaska. Reported from 

 Labrador. Also in Greenland, northern Europe 

 and Asia. June-Aug. 



18. Senecio lobatus Pers. Butterweed. 

 Cress-leaved Groundsel. (Fig. 4050.) 



5. O'ra/j/iMichx.Fl.Bor.Am.2: 120. 1803. Not L. 1753. 

 Senecio lobalus Pers. Syn. 2: 436. 1807. 



.\nnual, glabrous throughout, or slightly woolly 

 when young, fleshy and tender; stem hollow, sim- 

 ple or branched, i°-3'' high. Leaves 2'-io' long, 

 pinnately divided, the segments orbicular, oblong, 

 obovateorcuneate, obtuse,sinuate dentate, entire or 

 lobed, the terminal segment usually larger than the 

 others; lower and basal leaves slender-petioled; 

 heads numerous, y'^-io" broad, slender-peduncled 

 in terminal corymbs; involucre nearly cylindric, 

 2%" high, its bracts linear, acute, usually with no 

 small outer ones; rays 6-12; achenes minutely liis- 

 pidulous on some of the angles; pappus white, 

 somewhat longer than the involucre. 



In swamps, Missouri and southern Illinois to North 

 Carolina, New Mexico, Mexico and Florida. April- 

 Sept. 31 



