APRIL, 1904. PLANTS YUCATAN^: MILLSPAUGH & CHASE. 131 



stem and branches, and opposite, petioled, glabrate leaves, variously 

 3-5 parted (rarely simple) usually acuminate, serrate. Inflorescence 



a few flowered corymb, peduncles 

 striate, minutely pubescent, becom- 

 ing angled, and nearly glabrous. 

 Heads (in flower) 7 mm. high, 20-23 

 mm. broad, ray flowers about 5, 

 disk flowers numerous. Involucral 

 bracts in 2 series, outer shorter, lin- 

 ear spatulate, puberulent, ciliolate, 

 spreading at the tips; inner lanceo- 

 late, acuminate, the tips blunt and 

 densely short pilose. Ray corollas 

 white, tube short, ligule broadly 

 oblong; truncate 7 mm. long, 

 spreading; disk corollas nerved, 5 

 lobed. Receptacle convex: scales 

 linear-lanceolate, acuminate, nearly 

 equaling the disk flowers. Achene 

 dark chestnut, .7-.8x8-i3 mm.) linear oblong; in section irregularly 

 4 sided or innermost 3 sided; impressed-striate, the surface cellular 

 and sparsely covered with tawny tubercles, each bearing a spinule; 

 awns 2, retrorsely barbed, spreading in the outer, erect in the inner 

 achenes, 2 mm. long. The inner achenes longer and less spinescent 

 than the outer. 



Hab. Cozumel, 1885, Gaumer (Oliver) (Bidens pilosa L. Field 

 Col. Mus. Bot. 1:54); campo about Izamal, Jan. 23, 1895, Millspaugh 

 Armour Exped. 170 (Bidens Alausensis Ibid.}; "herb, 4 feet high, very 

 common in waste lands, flowers pure white, Izamal, Jan. to Dec." 

 Gaumer 451, "a smaller leafed form, 2 feet high, abundant at the port 

 of Silam," 6j2, Chichankanab 1469, San Anselmo 1771, Silam 1892. 



A species exceedingly variable in its leaf forms. Achenes some- 

 times merely spinulose, the tubercle obsolete or indicated by a pale 

 spot, the spinules rarely obsolete. This species is given by authors as 

 being radiate or discoid, and with achenes 2-4 awned; our specimens 

 all have conspicuous white rays and 2-awned achenes. Bidens pilosa 

 L. is given as the "discoid form" of the species named Coreopsis 

 leucantha L. Sp. PI. Ed. 2, 1282, in Kew Index and Griseb. Fl. Br. 

 W. I. 373. From the meager description given by Linnaeus and 

 uncertainty as to his type it seems best to hold our plants as B. leu- 

 cantha, with which they do agree, while they do not agree with B. pilosa. 



Bidens bipinnata L. Sp. PI., 832. 



An erect, simple, or branched annual with obtusely 4 angled, 

 glabrate stem, and opposite, long-petioled, bipinnate, thin, acuminate, 

 serrate, minutely pubescent leaves. Inflorescence of solitary, terminal, 

 and axillary long-peduncled heads, branches and peduncles glabrous, 

 striate, becoming sulcate. Heads (in flower) 9 mm. high, 12-15 mm - 

 broad, ray flowers about 5, disk flowers numerous. Involucre glan- 



