146 PROCEEDINGS OF THE AMERICAN ACADEMY. 



disk-corollas mostly exceeding the involucre, numerous : achenes smooth 

 (i. e. not warty), glabrous or glabrate, from fusiform to cuneate, those of 

 the ray-flowers 3-angled and 3-awned, of the disk-flowers strongly 

 flattened, 2-awned (in Z. aurea generally 3-awned and somewhat 3- 

 angled) ; body of the achene 3 to 6 mm. long, 1 to 2.5 mm. wide, the 

 angles never definitely winged but in several species produced into thin 

 longitudinally striate margins ; pappus of 2 to 3 short tooth-like or longer 

 rigid awns continuous with the edges of the achene, a series of very short 

 intermediate squamellae often present. 



* Intermediate scales (squamellae) of the pappus on the disk-achenes at least 

 0.5 mm. long. 



-»- Involueral bracts in 2 series. 



++ Involueral bracts recurved at tip. 



1. Z. serrata, La Llave. Shrub, 4 m. or more high, pubescent, 

 much-branched: leaves lanceolate, serrate, petiolate, stellate-pubescent 

 on both sides: heads corymbose; involucre of 10 to 12 ovate recurved 

 scales: ligules 10 to 12, ovate, emarginate. — Nov. Veg. Descript. 13 

 (1824); Hemsl. Biol. Cent.-Am. Bot. ii. 174. Lipochaeta? serrata, 

 DC. Prodr. v. 611 (1836). — Southern Mexico. Type collected by 

 La Llave at San Jose del Corral. No specimens examined, the above 

 description compiled. 



*+ ++ Involueral bracts not recurved. 



2. Z. monocephala, Sch. Bip. Shrub: leaves ovate-lanceolate, 2 to 

 10 cm. long, 0.5 to 5 cm. wide, acuminate at the apex, rounded or 

 somewhat acuminate at the base, serrate, scabrous above, very sparsely 

 strigillose beneath ; petioles 5 to 13 mm. long, very villous ou the upper 

 side : peduncles solitary, slender, monocephalous, shorter than the upper 

 leaves; heads 15 mm. high; involucre campanulate, 10 to 15 mm. broad, 

 the scales ovate, submembranaceous, about 2-seriate : ray-flowers 4 or 5: 

 achenes margined ; squamellae well developed. — Sch. Bip. in Seemann, 

 Bot. Voy. Herald, 306 (1852-57); Hemsl. Biol. Cent.-Am. Bot. ii. 

 173. Lipochaeta monocephala, DC. Prodr. v. 610(1836). — Southern 

 Mexico. State of Vera Cruz : Mirador, Sartorins. Of this rare and 

 imperfectly known species I have seen only a tracing with a leaf and 

 some immature achenes from the De Candollean Herbarium in Geneva. 



3. Z.. scaberrima, Benth. & Hook. f. Shrub (?) : leaves short- 

 petioled, ovate-lanceolate, acute at the apex, cuneate at the base, remotely 

 serrulate, very scabrous on both sides, 5-nerved: heads in a lax corymb; 



