WOOTON AND STANDLEY FLORA OF NEW MEXICO. 749 



129. BARTLETTIA A. Gray. 



Slender annual, nearly glabrous, with long-petiolate rounded repand-dentate 

 leaves and long -pedunculate, rather large heads, these heterogamous, radiate; invo- 

 lucre campanulate, of 12 to 14 oblong-lanceolate bracts in 2 or 3 series; achenes 

 cuneate-oblong, compressed; pappus of numerous unequal bristles in a single series. 



1. Bartlettia scaposa A. Gray, Mem. Amer. Acad. n. ser. 5: 323. 1854. 

 Type locality: On a prairie near Oorralitas, Chihuahua. 

 Range: Southern New Mexico, south into Mexico. 

 New Mexico: Lordsburg (.4. Davidson 1422). 



130. MESADENIA Raf. 



Perennial herb; leaves thrice pinnatiiid into narrow segments; heads 10 to 15 mm. 

 high, numerous, in corymbiform cymes; involucre turbinate, of a single series of 5 

 or 6 narrow bracts; flowers 5 or 6, with white corollas, none radiate; achenes glabrous. 



1. Mesadenia decomposita (A. Gray) Standley. 

 Cacah'o decomposite A. Gray, PI. Wright. 2: 99. 1853. 

 Type locality: Mountains east of Santa Cruz, Sonora. 



Range: Southern Arizona and southwestern New Mexico to northern Mexico. 

 New Mexico: San Luis Mountains (Mearns 2219, 527, 531). 



131. CENTAUREA L. Star thistle. 



Tall, usually simple-stemmed annual with alternate, spatulate to oblong-lanceolate, 

 entire or denticulate leaves and large showy heads of tubular flowers; involucre cam- 

 panulate. the bracts appressed in many series, pectinate; outer corollas pink or pur- 

 plish, enlarged and radiant, the inner ones ochroleucous ; achenes compressed, smooth ; 

 pappus of several series of unequal bristles. 



1. Centaurea americana Nutt. Journ. Acad. Phila. 2: 117. 1821. 



Plectoa phalua ameriexmus Don in Sweet, Brit. Flower Gard. 2: pi. 5/. 1823-29. 



Type locality: "On the banks of streams, and in denudated alluvial situations, 

 throughout the plains or prairies of the upper part of Arkansas territory." 



Range: Arkansas and Louisiana to Arizona and southward. 



New Mexico: Socorro; Mogollon Mountains; Maugas Springs; G S Ranch* 

 Mesilla; White Mountains; mountains north of Santa Rita. Moist slopes and along 

 streams, in the Upper Sonoran and Transition zones. 



132. CIRSIUM Hill. Thistle. 



Coarse biennial or perennial herbs with prickly, often pinnatind, sessile, alternate 



leaves and large heads, the latter solitary, raceino.se, or clustered at il nds of the 



branches; flowers all tubular, perfect; bracts of the involucre imbricated in many 

 ranks, mostly tipped with prickles; receptacle clothed with soft bristles; ach< 

 oblong or obovoid, compressed, smooth; pappus of numerous plumose bristles united 

 into a ring at the base, deciduous. 



KEY to THE BH I ii 3. 



Bracts deep purple, reflexed for half their length, nol arachnoid . I. C. i inaeeum. 

 Bracts nol purplish or [f so only at the very tips, when reflexed 

 more or Lee - arachnoid. 



Hani ■ acauleecenl 2. C. acaulescens. 



Plants not acaulescent. 



A i Lea i some of the bracts pectinate-ciliate with \w.ik 

 spine : flowei s greenish yellow. 



