1008 MISC. PUBLICATION 423, U. S. DEPT. OF AGRICULTURE 



2. Senecio multicapitatus Greenm. ex Rydb., Torrey Bot. Club Bui. 



33: 160. 1906. 

 Apache, Navajo, and Coconino Counties, 5,000 to 7,000 feet, plains 

 and mesas, May to November. Colorado, Utah, New Mexico, and 

 Arizona. 



3. Senecio longilobus Benth., PL Hartw. 18. 1839. 



Senecio filijolius Nutt., Amer. Phil. Soc. Trans, ser. 2, 7: 414. 



1841. Not Berg., 1767. 

 Senecio orthophyllus Greene, Leaflets 1: 221. 1906. 



Apache, Navajo, and Coconino Counties, south to Cochise, Santa 

 Cruz, and Pima Counties, 2,500 to 7,000 feet, common on dry stony 

 plains, mesas, and slopes, and along washes, May to November, type 

 of S. orthophyllus from Willow Spring, Apache County (Palmer 479 in 

 1890). Colorado and Utah, south to Texas and Mexico. 



Threadleaf groundsel. The United States Department of Agri- 

 culture has found S. longilobus to be one of the most poisonous of the 

 groundsels, especially to cattle and horses, the leaves of the new growth 

 being most toxic. The primary effect is to produce lesions in the liver. 

 This species is used extensively in the domestic medicine of the 

 Indians. 



4. Senecio monoensis Greene, Leaflets 1: 221. 1906. 



Senecio lathyroides Greene, Leaflets 2: 21. 1909. 

 Senecio jilicijolius Greenm., Mo. Bot. Gard. Ann. 1: 274. 1914. 

 Senecio pectinatus A. Nels., Wyo. Univ. Pub. Bot. 1: 141. 

 1926. 



Almost throughout the State, 1,200 to 6,000 feet, dry sandy or stony 

 soil on mesas and slopes, and in canyons, often in chaparral, flowering 

 in nearly all months, type of S. lathyroides from Pierce Spring (M. E. 

 Jones 5077), type of S. filicijolius from the Santa Cruz River valley 

 (Pringle 316 in 1881), type of S. pectinatus from near the Baboquivari 

 Mountains, Pima County (Hanson 1020). Utah and Arizona to 

 California and Mexico. 



A specimen from Superior (Whitehead 269) has a woolly involucre 

 and young branchlets and approaches S. douglasii DC, but other 

 specimens from the same region are definitely S. monoensis. The 

 latter is closely related to S. douglasii, differing chiefly in its essentially 

 glabrous character and its more herbaceous stem, and may be no more 

 than a variety. 



5. Senecio macdougalii Heller, Torrey Bot. Club Bui. 26: 592. 1899. 

 Apache and Coconino Counties to Cochise and Pima Counties, 



7,000 to 10,500 feet, coniferous forests, July to October, type from 

 Walnut Canyon, near Flagstaff (MacDougal 342). New Mexico and 

 Arizona. 



A specimen from the north end of the Carrizo Mountains (Standley 

 7376), identified by Greenman as S. ambrosioides Rydb., is the only 

 collection of that species cited by him from Arizona. (See footnote 

 11, p. 1005, Greenman, vol. 2, p. 596). The heads are young, but the 

 number of flowers (6 ray, 30 disk) agrees as well with S. macdougalii 

 as with S. ambrosioides. 



