28 Contributions from the Gray Herbarium 
which call for recognition. All the Mexican and Central American 
material examined has a pale straw-colored pappus, while most of 
the material from other localities has a pappus distinctly tinged 
with buffy or reddish-brown. Several South American specimens, 
however, even from Brazil, show a pappus identical in color with 
that of the Central American plants, which for the rest does not 
differ in number or length of setae from that of specimens from 
other localities. Much of the Central American material has dis- 
tinctly larger leaves than the other specimens, and slightly less 
hispid involucres, but these differences are by no means constant. 
These Central American specimens lead to a form, apparently most 
common in Central America but occurring also south to Brazil, 
and seemingly well worthy of recognition in nomenclature, in 
which the involucre is entirely glabrous, although in all other 
respects these specimens seem identical with the common Central 
American series. The identity and distribution of the forms here 
treated may be summarized thus. 
ERIGERON BONARIENSIS L. Sp. ii. 863 (1753), as bonariensé 
(typical form). — E. linifoliwm Willd. Sp. iii. 1955 (1804). Conyza 
ambigua DC. Fl. Fr. Suppl. vi. 468 (1815); Prod. v. 381 (1836). 
Conyza albida Willd. ex Spreng. Sys. iii. 514 (1826). Erigeron 
ambiguus (DC.) Sch. Bip. in Webb & Berth. Phyt. Canar. ii. 208 
(1836-50). E. albidwm (Willd.) Gray, Proc. Am. Acad. v. 319° 
(1861-62). Conyzella linifolia (Willd.) Greene, F\. Francis. 386 
(1897). Leptilon linifolium (Willd.) Small, Fl. 8. E. U. 8. ed. 1. 
1231 (1903). Leptilon bonariense (L.) Small, 1. ¢. (1903). — Other 
synonyms often cited are omitted as more or less doubtful. —A 
native of South America (Buenos Ayres), now spread over the Old 
World, Central America, the southeastern U. 8. (N. J. to Fla.), and 
Calif. — Primarily distinguished from E. canadense by its larger 
heads, 4.5~-6 mm. high. 
E. BONARIENSIS L. var. leiothecus, var. nov. Involucrum 
a es 3-seriatum 4-6 mm. altum., Caulis ut folia lanceo- 
— ol lanceolata quam in vulgari speciei forma multo gla- 
: Pig Peep ggg Rafael, Dept. Guatemala, 2135 m. 
heal es ; ps Holway 39 (ryen in Gray Herb.); iso 
hea isin ay a 830 m., Apr. 1892, Heyde & Lux 3371; 
Rati Alai tay 1886, Puerckheim 393. Costa Rica: pas 
ear Alajuelito, 1894, Tonduz (distr. Pitt. & Dur. 889): 

