APRIL, 1904. PLANTS YUCATAN^: MILLSPAUGH & CHASE. 



89 



linear-oblong, sparsely hirsute, punctate leaves; glomerules 1-1.2 cm. 

 long. Involucral bracts. pale, with green tips, appressed, acuminate, 

 glabrous or the outer sparsely hirsute, ^ the length of the inner. Corolla 

 white, nearly regular, 5 cleft. Receptacle minute. Achene brown, 

 1-1.2x516 mm.; oblong, tapering to the base; in section elliptic; 

 strongly 10 ribbed, the ribs hirsute, interspaces dark, glandular; 

 pappus of rigid, persistent, unequal awns and denticulate scales, inter- 

 rupted on the posterior side, the lateral pair of awns elongated and 

 twice reflexed, 5-5.5 mm. long. 



Hab. "Herb 3 feet high, in moist lands, not common, Nov.," 

 Izamal, Gaumer 1015; common at Yot Oor\ot, 1324. 



VERNONIA Schreb. Gen. PI., 2:541. 



Heads homogamous, discoid, flowers perfect, fertile, tubular. 

 Involucre wide campanulate (in our species), of dry or subherbaceous 

 bracts, imbricated in several series, unequal. Receptacle naked, 

 plane. Achene subterete, 10 nerved, villous; pappus in 2 series, outer 

 of few short scales, inner of numerous slender bristles. Herbs or 

 shrubs; heads many flowered, disposed in cymes. 



Vernonia arborescens (L.) Swartz Ind. Occ., 2:132. 



Conyza arborescens L. 



An erect, divaricately branched, fruticose herb, with terete, striate 

 canescent stem and branches, and alternate, short-petioled, ovate or 

 elliptic, acuminate, entire, veiny 

 leaves pubescent above, pilose- 

 canescent below. Inflorescence 

 scirpoid-cymose, terminating the 

 branches or axillary. Heads 

 sessile, usually subtended by a 

 small leaf, 15-25 flowered, 8 

 mm. high, as broad or broader. 

 Involucral bracts in 2-3 series, 

 densely canescent, outer subu- 

 late, spreading, inner acuminate, 

 erect or appressed. Corolla regu- 

 lar, 5 cleft, purplish blue. Re- 

 ceptacle faveolate. Achene 

 ashy-brown, . 7-. 8 x 1.6-1.8 mm., 

 cuneate-oblong; in section te- 

 retopentagonal ; apex truncate, 

 densely villous except the basal callus, 10 nerved, 5 nerves prominent 

 and 5 intermediate faint; pappus tawny, outer of linear, denticulate 

 scales, .3-. 5 mm. long, inner of numerous scabrous, capillary bristles, 

 4-6 mm. long. 



Hab. "Two to three feet high, rare," Calotmul, Gaumer 1311, 

 Yot Donot /J^j, "very rare; but one plant seen." 



A variable species. Yucatan specimens have heads somewhat larger 

 than other West Indian plants, and the subtending leaf very small or 

 wanting; leaves larger than common, and little or not at all rugose. 



