142 



FIELD COLUMBIAN MUSEUM BOTANY, VOL. III. 



wanting, or rarely a few present; petioles slender 5 to 10 mm. long - 

 peduncles 1.3 to 1.8 cm. long, slender, scarcely thickened upward; invol- 

 ucral bracts 5, oblong linear 

 1.2 cm. long, scarious margined, 

 usually browned at the tip, gfrands 

 dark, linear, usually biseriate, 

 heads usually nodding in anthesis; 

 flowers about 18, greenish white; 

 corolla p mm. long, puberulent upon 

 the outer surface, lobes 5, acute, 

 spreading; receptacle convex, 

 pitted ; achenes purplish black, 

 somewhat attenuate and (under 

 a lens) upwardly hispid and finely 

 striate, .5x8-9 mm.; in section 

 elliptical; pappus of copious, 

 slender, pale, or tawny, hispid- 

 ulous bristles 5-7 mm. long. 



This species is obviously related 

 to P. Ervendbergii Gray and P. nummularium DC. It is distinguished, 

 however, by the absence of the irregularly distributed superficial glands 

 which are present on the leaves, of both the species mentioned. It also has 

 somewhat shorter peduncles and larger leaves. 



Hab. Merida, at the Quinta del Obispo, Nov. 15, 1864, Schott 81 

 (Porophyllum Ervendbergii Field Col. Mus. Bot. 1:396); "shrubby, 15 

 feet high, common in the brushlands about Izamal," Gaumer 523 

 (Porophyllum nummularium Ibid. 1:325); Progreso, March 5, 1899, Mills- 

 fraugh PI. Utowance. 1648 (type) ; Merida, scrubby places in old Hene- 

 quen plantations, Feb. n, 1903, Ccze. et Ed. Seler 3831, and sunny 

 places near Oitas, March 17, 3975. 



Schott 81 and Gaumer 523 have leaves with irregularly disposed 

 glands in addition to the marginal and terminal ones, and Millspaugh 

 PI. Utowance 1648, the type, shows one leaf with 3 of these smaller 

 glands. These are not, however, "superficial," but thickened like the 

 marginal glands and emit a strong smelling oil when punctured. 



Called by the Mayas XPECHUEKIL; referring to the leaf glands in 

 their fancied resemblance to the indigenous species of wood-ticks 

 when engorged with blood. 



PECTIS L. Syst. Ed., 10:1221. 



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

 late; disk flowers perfect, fertile, tubular. Involucre cylindrical or 

 campanulate, of herbaceous equal bracts in i series, free. Receptacle 

 small, naked. Achene dorsally compressed, linear, pappus various: 

 Sec. Eupectis, of few unequal scales or awns; Sec. Pectothrix, of 

 numerous capillary bristles; Sec. Pectidium, of 1-4 subulate rigid 

 corneous awns. Heavy scented herbs with small heads. 



Pappus of thin scales 



Pappus of slender erect bristles 



Pappus of rigid divergent awns 



Prostrata. 



Schottii. 



linifolia. 



