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. 
+ Involucral bracts in 2 series. 
++ Involucral 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 José del Corral. No specimens examined, the above » 
description compiled. 
++++ Involucral bracts not recurved. 
2. Z. MONOCEPHALA, Sch. Bip. Shrub: leaves ovate-lanceolate, 2 to 
10 em. 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 on the upper? 
side: peduncles solitary, slender, monocephalous, shorter than the uppe? 
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. 1. 
173. Lipochaeta monocephala, DC. Prodr. v. 610 (1836). — Southern 
Mexico. Strate or Vera Cruz: Mirador, Sartorius. 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. scaBerrtma, Benth. & Hook. f, Shrub (?): leaves sbort- 
petioled, ovate-lanceolate, acute at the apex, cuneate at the base, remotely 
serrulate, very scabrous on both sides, 5-nerved: heads in a lax corymbs 
