[Vor. 4. 
28 - ANNALS OF THE MISSOURI BOTANICAL GARDEN 
Distribution: along streams, western Arizona to south- 
eastern California. 
Specimens examined: 
Arizona: Grand Сайоп of the Colorado River, May, 1884, 
Lemmon (U. S. Nat. Herb. No. 47166; fragments and photo- 
graph in Mo. Bot. Gard. Herb.); ‘‘Mohave region," April- 
May, 1884, Lemmon 3130 (Gray Herb.), probably a duplieate 
of the preceding; Wickenburg, valley of the Hassayampa 
River, April, 1876, Dr. E. Palmer 614 (Gray Herb., Phil. Acad. 
Nat. Sci. Herb., and Mo. Bot. Gard. Herb.); Pogumpa, 21 
April, 1894, M. E. Jones 5095n (U. S. Nat. Herb.) ; without 
locality or date of collection, Orcutt (Univ. Calif. Herb. No. 
131578). 
Nevada: ‘‘Meadow Valley Wash, mile 16,” alt. 1125 m., 
28 April, 1904, M. E. Jones (U. S. Nat. Herb. No. 856543); 
without locality, coll. of 1891, R. J. Jones (Mo. Bot. Gard. 
Herb.). 
California: Providence Mountains, 26 May, 1902, Bran- 
degee (Univ. Calif. Herb. No. 102018, and U. S. Nat. Herb. 
No. 735424). 
91. S. quercetorum Greene, Leafl. Bot. Obs. & Crit. 2: 20. 
1909. 
S. Arizonicus Gray, Syn. Fl. N. Am. 12: 392. 1884, and ed. 
2, 1886, in part, as to plant of Rusby. 
S. macropus Greenm. Monogr. Senecio, I. Teil, 24. 1901, 
and in Engl. Bot. Jahrb. 32: 20. 1902; Ann. Mo. Bot. Gard. 
1: 267. 1914. 
A stout herbaceous perennial; stems erect, 7.5 to 10 dm. 
high, glabrous or white tomentulose in the axils of the leaves, 
striate, more or less purplish, often hollow; radical and 
lower stem-leaves petiolate, lyrately pinnatifid into few and 
relatively small unequal euneate dentate to linear and entire 
lateral lobes and a large 5 to 8 em.-long oblong-ovate coarsely 
dentate terminal segment, glabrous on both surfaces and, as 
well as the stem, more or less glaucous ; upper stem-leaves ses- 
sile, pinnately lobed and conspicuously amplexicaul, gradually 
reduced towards the terminal open corymbose cyme; heads 
