WOOTON AND STANDLEY PLOEA OF NEAV MEXICO. 623 



Type locality: "On the banks of the Missouri." 

 Range: British America to Michigan, Kansas, and New Mexico. 

 New Mexico: Farmington; Tunitcha Mountains; Dulce; Pescado Spring; Johnsons 

 Mesa; Pecos; Perico Creek; Santa Fe; Silver City; Mangas Springs; ]\Iogoiion Moun- 

 tains; Mesilla Valley; White and Sacramento mountains. Open slopes and in waste 

 ground, in the Upper Sonoran and Transition zones. 



3. Lactuca ludoviciana (Nutt.) DC. Prodr. 7: 141. 1838. 

 Sonchus ludovicianus Nutt. Gen. PI. 2: 25. 1818. 



Type locality: "In humid places, in the open plains, and Fort Mandan on the 

 Missouri." 



E.ANGE : Montana and Minnesota to New Mexico and Texas. 



New Mexico: Farmington ( Tl^ooton 2592). River valleys, in the Upper Sonoran 

 Zone. 



4. Lactuca canadensis L. Sp. PI. 796. 1753. 

 Type locality: "Habitat in Canada." 



Range: British America to New Mexico and Florida. 



New Mexico: Tunitcha Mountains; Gallinas Canj'on; Sandia Mountains; Mimbrea 

 River; Ruidoso Creek. Upper Sonoran and Transition zones. 



5. Lactuca gramitiifolia Michx. Fl. Bor. Amer. 2: 85. 1803. 

 Type locality: "In Carolina inferiore." 



Range: Colorado and Arizona to North Carolina and Florida. 



New Mexico: Winsors Ranch; Las Vegas; South Percha Creek; Middle Fork of the 

 Gila; Parkers Well; Cloudcroft; Tularosa Creek; Ruidoso Creek. Open slopes and 

 meadows, in the Upper Sonoran and Transition zones. 



8. SONCHUS L. Sow thistle. 



Succulent annuals or biennials with alternate, auriculate-clasjDing, dentate or 

 pinnatifid, prickly leaves, and corymbs of medium-sized heads of yellow flowers; 

 involucre ovoid or campanulate, becoming thickened at the base, the bracts im- 

 bricated in several series, the outer successively smaller; receptacle flat, naked; 

 achenes oval, flattened, ribbed, truncate; pappus of soft smooth capillary bristles. 



KEY to the species. 



Heads 25 mm. high; involucres glandular-pubescent 3. S. arvensis. 



Heads about 15 mm. high; involucres not glandular-pubescent. 



Auricles of leaves acute; achenes not transversely wrinkled 1. S. asper. 



Auricles obtuse; achenes transversely wrinkled 2. S. oleraceus. 



1. Sonchus asper (L.) All. Fl. Pedem. 1: 222. 1785. 

 Sonchus oleraceus asper L. Sp. PI. 794. 1753. 



Type locality: European. 



New Mexico: Farmington; Carrizo Mountains; Pecos; Santa Fe; Sandia Moun- 

 tains; Mangas Springs; Berendo Creek; Cloverdale; Mesilla Valley; Fresnal; Round 

 Mountain. 



A common weed in gardens and cultivated fields, widely introduced into North 

 America from Europe. 



2. Sonchus oleraceus L. Sp. PL 794. 1753. 

 Type locality: "Habitat in Europae cultis." 

 New Mexico: Kingston; Patterson. 

 Introduced from Europe. 



3. Sonchus arvensis L. Sp. PL 793. 1753. 



Type locality: "Habitat in Europae agris argillosis." 



New Mexico: Shiprock {Standley 7825). 



Abundant along irrigating ditches in this one locality; introduced from Europe. 



