STANDLEY TREES AND SHRUBS OF MEXICO 1625 



5. Senecio alvarazensis Greenm. Field Mus. Bot. 2: 349. 1912 

 Northern Mexico; type from Alvdrez, San Luis Potosi. 



Suffruticose; stems erect, branched, above striate and flocculent-tomentose- 

 upper leaves sessile and auriculate-clasping, irregularly laciniate-lobed or sub- 

 pinnate, 3 to 8 cm. long, 1 to 4.5 cm. broad, arachnoid-tomentulose above, densely 

 and persistently white-tomentose beneath; inflorescence cymose, many-headed- 

 heads about 1 cm. high, radiate; bracts of the involucre usually 21, lanceolate' 

 7 to 8 mm. long, black-tipped; ray flowers 10 to 12; rays yellow; disk flowers 

 about 50; achenes canous-hirtellous. 



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



California to northern Baja California and Sonora; type from California. 



Sufi-ruticose, white-tomentose to nearly or quite glabrous; stems erect, more 

 or less branched; leaves thickish, hnear and entire to pinnately divided into 3 

 to several long, hnear, acute divisions, the margins revolute; inflorescence termin- 

 -ating the stem and branches in a few-headed corymbose cyme; heads 1 to 1.5 cm. 

 high, nearly as broad, radiate; involucre conspicuously calyculate; bracts of the 

 involucre usually 21; ray flowers about 12; rays yellow; disk flowers about 60; 

 mature achenes 4 to 5 mm. long, canescent-pubescent with upwardly appressed 

 hairs. 



7. Senecio filifolius Nutt. Trans. Amer. Phil. Soc. n. ser. 7: 414. 1841. 

 Southwestern United States, mainly east of the Rocky Mountains, to Coahuila 



and Chihuahua; type from "banks of the Missouri, towards the Rocky Moun- 

 tains." 



Suffruticose, white-tomentose to nearly glabrous; stems erect, usually branched, 

 leafy; leaves linear and entire to pinnately divided into few to several linear divi- 

 sions, the margins revolute; heads few to several, 1 to 1.5 cm. high, radiate; 

 involucre not conspicuously calyculate, the bracteoles mostly less than half as 

 long as the 21 bracts of the involucre; ray flowers 8 to 13; rays yellow; disk 

 flowers 40 to 50; achenes canous-hirtellous. 



8. Senecio flaccidus Less. Linnaea 5: 161. 1830. 

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

 Senecio longilobus Benth. PI. Hartw. 18. 1839. 

 Chihuahua to Hidalgo; type from the Llanos de Perote. 



Suffruticose, more or less deciduously white-tomentose; stems 1 meter or less 

 high; leaves 2 to 8 cm. long, flaccid, linear and entire to pinnately divided into 

 few linear, elongate, divaricately spreading lateral divisions; heads 10 to 12 mm. 

 high, radiate; involucre calyculate with short setaceous bracteoles; bracts of the 

 involucre usually 13, about 6 mm. long, tomentulose to glabrous; achenes seri- 

 ceous-pubescent. 



9. Senecio picridis Schauer, Linnaea 19: 733. 1847; 20: 697. 1847. 

 South Mexico; type from Zimapdn, Hidalgo. 



Stems erect, 1 meter or less high, ligneous below, floccose-tomentose; leaves 

 narrowly lanceolate, 3 to 13 cm. long, 5 to 10 mm. broad, acute, entire or incon- 

 spicuously denticulate, at first arachnoid-tomentulose but more or less glabrate 

 above, permanently white-tomentose beneath, the lowermost leaves gradually 

 narrowed into a slightly winged petiole, the upper leaves sessile and auriculate or 

 subsagittate at the base; heads 8 to 10 mm. high, radiate; bracts of the involucre 

 usually 21; ray flowers 8 to 10; rays yellow; disk flowers numerous; achenes 

 sericeous-hirtellous. 



10. Senecio carnerensis Greenm. Moiiogr. Senecio 1: 25. 1901; Bot. Jahrb. 

 Engler 32: 22. 1902; Ann. Mo. Bot. Gard. 1: 273. 1914. 



Northern Mexico; type from Carneros Pass, Coahuila. 



