STANDLEY — TKEES AND SHRUBS OF MEXICO. 621 



Flowers monoecious. 



Petals of the pistillate flowers lance-linear 6. D. guatemalensis. 



Petals of the pistillate flowers ovate or rhombic-ovate. 



Leaves linear to lanceolate 7. D. sericophylla. 



Leaves mostly ovate to oval. 



Staminate petals longer than the calyx 8. D. manzanilloana. 



Staminate petals shorter than the calyx , 9. D. tinctoria. 



1. Ditaxis heterantha Zucc. Abh. Akad. Wiss. Mlinchen 15^: 735. 1829-30, 

 Argithamuia argentea T. S. Brandeg. Univ. Calif. Publ. Bot. 4: 273. 1912. 

 Sinaloa, Quer^taro, Guanajuato, Hidalgo, and San Luis Potosi ; type from 



Tollman, Queretaro. 



Shrub with thick woody stems ; leaves ovate or broadly ovate, 4 to 8 cm. 

 long, acute or acuminate, entire or nearly so, short-petiolate, whitish-sericeous 

 beneath, at least when young; inflorescence slender-pedunculate. "Azafran- 

 cillo " (Queretaro) ; " azafran de bolita " (Jalisco). 



The plant is eniployetl as a dye ; the seeds are said to be edible, with a flavor 

 like that of walnuts. 



2. Ditaxis brandegei (Millsp.) Rose & Standi. Contr. U. S. Nat. Herb. 16: 13. 



1912. 



Argithamnia hrandegei Millsp. Proc. Calif. Acad. II. 2: 220. 1889. 



Baja California and Sonora ; type from San Gregorio, Baja California. 



Shrub, 1 to 2 meters high, glabrous throughout, the stems usually purplish 

 and glaucescent ; leaves lanceolate or ovate, 2 to 7 cm. long, acute, finely ser- 

 rate, long-petiolate ; flowers in slender racemes. 



3, Ditaxis pringlei (Greenm.) Pax & Hoffm. in Engl. Pflanzenreich IV. 147^': 



66. 1912. 



Argithamnia pringlei Greenm. Proc. Amer. Acad. 41: 239. 1905. 



Known only from the vicinity of the type locality, Cuemavaca, Morelos. 



Shrub, 1 to 1.5 meters high; leaves orbicular to ovate, 3 to 8 cm. long, 

 rounded to acute at apex, short-petiolate, entire or denticulate, white-tomentose 

 beneath. 



4, Ditaxis lanceolata (Benth.) Pax & Hoffm. in Engl. Pflanzenreich IV, 147^': 



71. 1912. 

 Serophyton lanceolaium Benth. Bot. Voy. Sulph. 52. 1844. 

 Argyrotliamnia lanceolata Muell. Arg. Linnaea 34: 145. 1845. 

 Baja California and Sonora ; type from Magdalena Bay, Baja California, 

 Slender, sparsely leafy shrub ; leaves linear to lanceolate, 1.5 to 4 cm. long, 

 entire, sericeous. 



5, Ditaxis palmeri (S. Wats.) Pax & Hoffm. in Engl. Pflanzenreich IV, 147"^': 



64. 1912. 

 Argithamnia palmeri S, Wats. Proc. Amer. Acad. 24: 77. 1889. 

 Known only from the type locality, Guaymas, Sonora. 



Slender shrub ; leaves mostly lanceolate, 3 to 6 cm. long, long-acuminate, en- 

 tire or nearly so, short-petiolate, green, nearly glabrous. 



6. Ditaxis guatemalensis (Muell. Arg.) Pax & Hoffm. in Engl. Pflanzenreich 



IV, 147"': 59. 1912. 

 Argyrothamnia guatemalensis Muell. Arg, Linnaea 34: 145. 1865. 

 Jalisco to Guerrero and Puebla. Type from Guatemala. 

 Shrub, about a meter high ; leaves ovate to ovate-oval, 1.5 to 7 cm. long, 

 acute or acuminate, short-petiolate, sericeous, serrulate. 



