n6 



FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



Hab. Tizimin, March 28, 1866. Schott sine num.; "herb 5 feet 

 high among the shrubbery of the brushlands and forests near Izamal, 

 Oct. to Jan." Gaumer 976, 2507, March n, 1903, Ccec. et Ed. 

 Seler 3920; Chichankanab Gaumer 1425, 2Opo, 2113, Calotmul 2110, 

 2 399, San Anselmo 2114, Pocoboch 2388, 2400; woodlands about 

 Chichen Itza, Millspaugh PI. Utowana 1635 (Ageratum paleaceum? 

 Field Col. Mus. Bot. 2:106). 



Called by the Mayas CHABANKAN, "A plant upon which ants 

 collect in great numbers." 



BORRICHIA Adans. Fam., 2:130. 



Heads heterogamous, radiate, ray flowers pistillate, fertile, ligu- 

 late; disk flowers perfect, fertile, tubular. Involucre hemispheric of 

 somewhat fleshy bracts imbricated in 3 series. Receptacle plane or 

 convex, chaffy; scales, concave, rigid, loosely embracing the achenes 

 and deciduous with them. Achene acutely 4 angled or in the rays 3 

 angled; pappus a thick, toothed crown. Rather fleshy, usually silvery 

 canescent, sea-coast shrubs. 



Achene 2.8 mm., obovoid-oblong 

 Achene 3.6-4 mm., oblong 



argentea 

 a,} borescens 



Borrichia argentea (H. B. K.) DC. Prod., 5:489. 

 Diomedea argentea H. B. K. \ 



A low shrub with pale stem and slender branches and opposite, 



sessile, linear-oblanceolate, mu- 

 cronate, canescent or glabrate 

 leaves. Inflorescence of solitary, 

 peduncled heads, terminal and 

 axillary; peduncles stout, rigid, 

 striate, silvery canescent. Heads 

 8-9 mm. high, 15 mm. broad; 

 ray flowers 12-15, disk flowers 

 numerous. Involucral bracts 

 shorter than the disk, ovate, ab- 

 ruptly acuminate, with spreading, 

 mucronate tips, the outer shorter, 

 silvery canescent, the inner cilio- 

 late. Corollas yellow, ray with a 

 short tube, ligule oval, 5 mm. 

 long, minutely tridentate, spread- 

 ing; disk corollas cylindrical, 5 lobed. Receptacle flat or slightly 

 convex; scales obovate, spinose tipped, indurated at maturity, falling 

 from the receptacle lightly clasping the achen'e. Achene black, 1.3 

 x 2.8 mm., obovoid-oblong, abruptly tapering at the base; in section 

 lozenge shaped, the angles acute, the facets plane or little concave; 

 glabrous; pappus a thickened 4-toothed crown, .8-. 9 mm. high. 



Hab. "Shrub, 2 feet high, abundant on the coast. Progreso," 

 Gaumer 1161, Chichankanab 2209. 



No. 2209 Gaumer shows two leaves toothed at the base as in 

 Borrichia frutescens (L.) DC., and in general our specimens show B. 



