1G0 PROCEEDINGS OF THE AMERICAN ACADEMY. 



somewhat exceeding the involucre: achenes 4 to G mm. long, slightly 

 rugose, those of the disk-flowers narrowly, of the ray-flowers broadly 

 winged ; squamellae well developed, usually united at the base to form 

 a short cup on the summit of the achene, the neck evident at least in the 

 achenes of the disk-flowers; awns shorter than the body, rather rigid. — 

 PI. Wright, i. 112 (1852); Hemsl. Biol. Cent. -Am. Bot. ii. 172.— 

 Southwestern United States and northern Mexico. Specimens examined, 



— Texas: hills near Eagle Pass, alt. 250 m., Pringh, no. 9089 ; Palmer 

 no. 625 (coll. of 1880) ; in the valley of the Rio Grande below Dofiana, 

 Mexican Boundary Survey, no. 591 ; limestone rocks 112 km. below El 

 Paso, Parry (coll. of 1852) ; Wright, no. 353 ; Chisos Mountains, Havard, 

 no. 10. Chihuahua : near the city, Pringh, nos. 41, 849, 998. Nuevo 

 Lkox: Soledad, Palmer, no. 625 (coll. of 1880). Coahuila : Saltillo, 

 Palmer, no. 803; Mesillas, Gregg, no. 534 (type, in herb. Gray). San 

 Luis Potosi : near the city, alt. 2000 to 2500 m., Parry & Palmer, 

 no. 451. 



* * Leaves larger, the cauline, 5 cm. or more in length (sometimes shorter in Z. 

 hispida). 



•»- Achenes angular, only slightly constricted at the summit (except in Z. virgulta) ; 

 awns generally about as long as the body (but short and toothdike in Z. yoija- 

 zensis). 



++ Awns short and tooth-like; ray-achenes scarcely 3 mm. in length. 



31. Z. goyazensis, Benth. & Hook. f. Stem woody, terete, scabrous ; 

 leaves 10 to 15 cm. long, 5 to 7 cm. broad, ovate or ovate-lanceolate, acute, 

 subcordate or cuneate-attenuate at the base, serrate-dentate, above some- 

 what scabrous, beneath sparsely tomentose ; petioles about 3 cm. long : 

 peduncles terminal, usually 2.5 cm. long; heads 1.5 cm. high; involucre 

 about 1 cm. broad, 2-seriate ; outer bracts obtuse, foliaceous, scabrous, 

 commonly equalling the disk-flowers: ray-flowers about 10; ligules ob- 

 long : achenes with short tooth-like awns and a short crown of paleaceous 

 Sfpiamellae ; achenes of the ray-flowers wingless, obpyramidal, 3-angled, 

 about 3 mm. long; those of the disk-flowers more or less winged, 4 to 

 5 mm. long, flattened. — Gen. ii. 373 (1873). Lipochaeta goyazensis, 

 Gardn. in Hook. Lond. Jour. Bot. vii. 406 (1848) ; Walp. Ann. ii. 867. 



— South America. Specimens examined, — Brazil : near San Domingos, 

 Province of Goyaz, Gardner, no. 4235 (co-type, in herb. Gray). This 

 is the most southern species of Zexmenia and its achenial characters are 

 very unlike all others. 



