APRIL, 1904. PLANTS YUCATAN^E MILLSPAUGH & CHASE. 135 



Heads 10 mm. high 16 mm. broad, ray flowers 5-6; disk flowers 

 30-40. Involucral bracts in 5-6 series, the outermost foliaceous, bract- 

 like, spreading, acute, puberu- 

 lent; the inner appressed, broad, 

 / obtuse, membranaceous with 

 scarious margins. Rays yellow, 

 tube slender, ligule oblong, 3 

 dentate or subentire, 4-4.5 mm. 

 long, spreading; disk corollas 5 

 lobed. Receptacle short conoid ; 

 scales narrow, laciniate, decidu- 

 ous with the achenes, but not 

 enfolding them. Achene dark 

 brown, .6-. 7 x 2.7 mm., oblong- 

 obconoid with attenuate, sub- 

 oblique base; in section elliptic j 

 clothed, except the base, with 

 long weak hairs ; pappus of about 

 20 stramineous, narrow, acu- 

 minate, laciniate scales, 3.5-4 mm. long. 



Hab. Shrubby 5-6 feet high, flowers yellow, Tunkas, March 3, 

 1890, Stone 243, 245 (in Herb. Acad. Sci. Phil.); "shrubby 15 feet 

 high, ascending among shrubs in the brushlands near Izamal, Gaumer 

 956, Chichankanab 2096, San Anselmo 2097 ; Oitas, open sunny places, 

 Men. 17, 1903, Cac. et Ed. Seler 3960. 



TRIDAX L. Sp. PL, 900. 



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

 late; disk flowers perfect, fertile, tubular. Involucre wide-campanu- 

 late or subhemispheric, of herbaceous bracts Imbricated in few series. 

 Receptacle plane or convex, 

 chaffy; scales membranaceous, 

 subtending the disk flowers'. 

 Achene subterete; villous; pap- 

 pus of many plumose-ciliate, 



slender, acuminate awns. Per- "^WS^tf \ . ; ; 



ennial herbs with long peduncled 

 heads of medium size. 



Tridax procumbens L. Sp. 



PL, 900. 



A diffuse, branching, pubes- 

 cent herb, more or less procum- 

 bent at the base, with opposite, 

 petioled, lacerate-lobed, hirsute 

 leaves. Inflorescence of solitary, 

 long-peduncled heads, terminal 

 and axillary; peduncles slender, 

 retrorsely pubescent. Heads 10 mm. high, 12-15 mm. broad, ray 

 flowers about 5, disk flowers numerous. Involucral bracts in 2-3 



