FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



duriform, the upper lanceolate, 

 peduncled heads, terminating the 



t 



Inflorescence of solitary, long- 

 branches, peduncles slender, hir- 

 sute. Heads 8 mm. high, 10-12 

 mm. broad; ray flowers 5-7 (usu- 

 ally but 5 perfecting fruit), disk 

 flowers numerous. Outer invo- 

 lucral bracts 3-5, imbricated, 

 ovate, acuminate, pubescent with 

 rigid white hairs; inner bracts 

 flattened on the back, truncate, 

 hirsute with stiff bristle-like 

 hairs which disappear at matur- 

 ity, becoming a hard, irregularly 

 trapezoid, warty, reticulate, and 

 rigid, pericarp-like covering for 

 the achene, to which it is closely 

 adherent (shown magnified 5 

 diameters in the figure). Cor- 

 ollas yellow, ligules broadly oval, 4-5 mm. long, bifid, spreading or 

 drooping; disk flowers 5 lobed. Receptacle conoid, elevated, the 

 fructiferous bracts saccate around it below their point of attachment; 

 scales fimbriate. Achene dull black, 1.5-2 x 2.1-2.5 mr n., unsymmetri- 

 cally obovoid; in section obovoid-cuneate, the dorsum truncate; 

 striate with impressed lines, glabrous. 



Hab. "Herb, 4 feet high, in the forests about Izamal," Gaumer 

 789 (Melampodium hispidum Field Col. Mus. Bot. 1:324), Progreso, 



2349- 



A species variable in the shape of its leaves and in the size of the 



fructiferous bracts; about one-tenth of a large collection (Gaumer 789) 

 having larger, more warty "pericarps" than in other specimens from 

 Yucatan and Mexico, but otherwise 

 these plants show no distinctions 

 worthy of specific or varietal rank. 



PARTHENIUM L. Sp. PL, 988. 



Heads heterogamous, radiate, 

 rays in i series, pistillate, fertile, 

 ligulate, the ligules short and broad ; 

 disk flowers perfect, sterile, tubular. 

 Involucre depressed hemispheric, of 

 herbaceous bracts imbricated in few 

 series. Receptacle chaffy, convex 

 or conic ; scales somewhat cucullate, 

 partly enclosing the sterile flowers. 

 Achene dorsally compressed, with a 

 callous margin which is firmly co- 

 herent at the base with the bases of the bracts of the contiguous pair of 

 sterile flowers and ot the subtending bract; at maturity tearing away 

 from the achene to the shoulder, carrying the empty sterile bracts and 

 the twice-split subtending bract on their basal extremities, forming a 



