io6 



FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



BALTIMORA L. Mant. PL, 158. 



Heads heterogamous, radiate; rays in i series, pistillate, fertile, 

 ligulate; disk flowers, perfect, sterile, tubular. Involucre campanu- 

 late, of 2 series of imbricated bracts, rigid with herbaceous tips. 

 Receptacle plane, chaffy; scales subtending or embracing the sterile 

 flowers. Achenes 3 sided, thickened, rugose; pappus a small crateri- 

 form, deciduous disk. Annual herbs, heads in loose panicjes. 



Baltimora recta L. Mant. PL, 288. 



An erect, branching, annual, with opposite, slender petioled, 

 ovate, acuminate, serrate, hirsute leaves. Inflorescence a loose, 



cymose panicle of several to 

 many heads; branches and pe- 

 duncles slender, striate, hirsute. 

 Heads 5-6 mm. high, 12-15 mm - 

 broad, ray flowers 5-6, disk flow- 

 ers numerous. Involucral bracts 

 subequal, appressed, ovate, acu- 

 minate, hirsute, especially toward 

 t he summit, striate. Corollas 

 yellow, rays with short tube, 

 ligule oval, 6 mm. long, emargi- 

 nate, spreading; disk corollas 

 campanulate, 5 lobed, the lobes 

 hirsute within. Receptacle sub- 

 convex ; scales oblong-lanceo- 

 late, acuminate, hirsute at the 

 summit. Achene black, 2.5-2.7 

 X3-3.2 mm., irregularly cuneate ; 



in section triangular; rugose, hirsute at the summit, 3 angled, the 

 angles corky margined, the margins produced into irregularly toothed 

 wings above, those of the lateral angles more prominent than the 

 ventral; papp'us crateriform, .5 mm. high, the margin fimbriate-hirsute. 

 Hab. "Herb, 4 feet high, common at Progreso," Gaumer 1177, 

 abundant at Buena Vista Xbac, 1423; Chichen Itza, Mch. 2, 1903, 

 C<zc et Ed. Seler 4001. 



Called ZALAC-KAAT by the Mayas. "Light thatch-KAAT." 



MELAMPODIUM L. Sp. PL, 921. 



Heads heterogamous, radiate, rays in i series, pistillate, fertile, 

 ligulate; disk flowers perfect, sterile, tubular. Involucre hemispheric, 

 in 2 series, dimorphous, outer series of 4 or 5 broad foliaceous bracts, 

 often connate at the base; inner hooded, completely and permanently 

 enclosing the achene, forming a pericarp-like covering, and deciduous 

 with it. Receptacle chaffy, convex or conical; scales subtending the 

 sterile flowers. Achene laterally compressed, striate, hilum above 

 the base, apex over the ventrum; pappus none. Herbs with rather 

 showy heads of yellow flowers. 



Fruit rugose in regular ridges. 

 Fruit rugose in irregular lines. 



divaricatum 

 gracile 



