470 PROCEEDINGS OF THE AMERICAN ACADEMY. 



420, 1111, Piaos Altos Mts., Greene, no. 145; Arizona, ravines about 

 Camp Grant, 23 April, 18G7, Palmer, no. 106, banks south of Camp 

 Apache, Hothrock, no. 271, Santa Catalina Mts., and at Ft. Bowie, 

 Lemmon, no. 127, also on Santa Catalina Mts., altitude 770 to 925 m., 

 17 April, 1881, Pringle, Lemmon^ no. 527 ; Texas, El Paso, Tliurher, 

 nos. 179, 1118, at Belknap, Sutton Hayes, no. 327 ; N. W. Mexico, 

 Seemann (without number) ; Sonora, about Hermosillo, Crawford, 1888 ; 

 S. W. Chihuahua, August to November, 1885, Palmer, no. 413; Coa- 

 huila, Mts., 14.5 km. east of Saltillo, July, 1880, Palmer (without num- 

 ber) ; region of San Luis Potosi, Schaffner, no. 842 a, and at Soledad, 40 

 km. southwest of Monclova, September, 1880, Palmer, no. 415 ; Morel os, 

 at Tres Marias near Cuernavaca, altitude 2920 m., Pringle, no. 7233, 

 A species on the one hand, through var. setulosum, approaching the 

 South American R. ciliatum, Hemsl., and on the other, through the var. 

 hispiduliim, the Mexican R. polyplocum, Hemsl. 



Var. setulosum. Leaves setulose-ciliate : fruit granulose-hispid, 

 otherwise like the species. — R. microphyllum, Hemsl. Biol. Cent.-Am. 

 Bot. ii. 63, in part. — Zimapan, Th. Coulter, no. 186; region of San 

 Luis Potosi, Parry & Palmer, nos. 309, 310. 



Var. hispidulum. Habit of the species proper : stem and leaves 

 covered with a scattered short hispidulous pubescence : fruit essentially 

 glabrous, or somewhat granulose. — R. polyplocum, Hemsl. Biol. Cent.- 

 Am. Bot. ii. 63, in part. — Valley of San Luis Potosi, Schaffner, no. 

 842; region of San Luis Potosi, altitude 1850 to 2460 m., Parry «& 

 Palmer, no. 308. Approaching the following species in the character of 

 the pubescence, but having a distinctly different habit. 



7. R. polyplocum, Hemsl. Herbaceous, closely hispidulous- 

 pilose throughout : stems much branched forming dense mats ; branches 

 very slender, obtusely tetragonal as in the pi-eceding species : leaves 

 acute or obtusish, not distinctly cuspidate-tipped : flowers solitary, sessile 

 in the small involucral bracts : fruit sessile or nearly so, small, white- 

 granulose or glabrous. — Biol. Cent.-Am. Bot. ii. 63. — Southern Mexico, 

 ]\Iirador, Liebmann, no. 244, and (according to Herasley) no. 243 ; also 

 Linden, no. 516. 



R. AscHENBORNii, Hemsl. Biol. Cent.-Am. Bot. ii. 62, is Galium 

 Aschenbornii, Schauer, treated above. 



