APRIL, 1904. PLANTVE YUCATAN^: MILLSPAUGH & CHASE. 117 



argentea to have a closer relationship to this species than to B. arbor- 

 escens (L.) DC. 



Borrichia arborescens (L.) DC. Prod., 5:489. 



Buphthalmum arborescens L. 



A whitish shrub with numerous short branches and opposite, 

 fleshy, oblanceolate, mucronate, white canescent or glabrate leaves, 

 tapering into a semi-clasping base. Inflorescence of solitary heads 

 terminating the numerous branches, peduncles stout, rigid, striate, 

 silvery canescent. Heads 12-15 mm - n 'g n > 22-23 mm - broad, ray 

 flowers 15-20, disk flowers numerous. Involucral bracts longer than 

 the disk, fleshy, subequal, appressed, the outer oblong-panduriform 

 acute, mucronate, canescent; the inner oblong-ovate, subacute or 

 obtuse, membranaceous at the summit. Corollas yellow, ray with 

 tube YZ the length of the ligule, 

 ligule oval 6-8 mm. long, acute, 

 entire, ascending; disk corollas 

 cylindrical, 5 lobed. Receptacle 

 flat; scales oblanceolate, acute, 

 membranaceous, falling from 

 the receptacle lightly clasping 

 the achene. Achene black, 

 1.2x3.6-4 mm., oblong, nar- 

 rowed at the base; in section 

 lozenge shaped, the angles 

 keeled, the facets plane; glab- 

 rous; pappus a thickened 4- 

 toothed crown, 1.3-1.5 mm. high. 



Hab. Seashore, Cozumel 

 1885, and Islands of Mugeres and 

 Holbox 1886, Gaumer (Oliver); 



coral rocks east shore of Cozumel, Millspaugh PL Utowana 1586 

 {Borrichia argentea Field Col. Mus. Bot. 2 :io7) this specimen being the 

 host of the type of Sorosporium Borrichise E. & E. Ibid. 2:16. 



This, the only specimen of Bonichia arborescens we have from 

 Yucatan, is the canescent form; but that this canescence has no 

 specific value is shown by specimens from Grand Cayman, Millspaugh 

 PI. Utowante 1247 (Field Col. Mus. Cat. No. 61247) and St. Croix, 

 Ricksecker 24 (Field Col. Mus. Cat. No. 70324), which have both 

 canescent and glabrate leaves on the same branches. While the 

 leaves of the canescent form of B. arborescens resemble those of B. 

 argentea, the larger heads with appressed involucre exceeding the disk 

 easily distinguish it from that species. 



TITHONIA Desf. Ann. Mus. Par., 1:46, t. 4. 



Heads heterogamous, radiate; ray flowers neutral, ligulate; disk 

 flowers perfect, fertile, tubular. Involucre hemispheric, of rigid, 

 appressed, striate bracts, with loose, foliaceous tips, imbricated in 2-3 

 series. Receptacle convex, chaffy; scales complicate, embracing the 

 achenes, persistent on the receptacle. Achene laterally compressed, 



