402 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



KEY TO THE SPECIES. 



Plants hirsute 1. D. neomexicana. 



Plants glabrous. 



Stems slender, much branched; leaves petiolate 2. D. laevis. 



Stems stout, simple; leaves sessile ?>. D. cyanophylla. 



1. Ditaxis neomexicana (Muell. Arg.) Heller, Cat. N. Amer. PI. 5. 1898. 

 Argyrothainnia neonwxicana Muell. Arg. Linnaea 34: 19. 1865. 



Type locality: "In Novo-Mexico." The types are Wright's 643 and 1797. The 

 first of these is certainly Texau, but the second may have come from New Mexico. 

 Range: Western Texas to Arizona and adjacent Mexico. 

 New Mexico: South of Hillsboro (J/etoZ/e 1287). 



2. Ditaxis laevis (Torr.) Heller, Cat. N. Amer. PI. 5. 1898. 

 Aphora laevis Torr. U. S. & Mex. Bound. Bot. 196. 1859. 

 Argyrothamnia laevis Muell. Arg. Linnaea 34: 147. 1865. 

 Type locality: Western Texas. 



Range: Western Texas and southern New Mexican. 



New Mexico: Roswell and vicinity. Dry plains, in the Lower Sonoran Zone. 



3. Ditaxis cyanophylla Woot. & Standi. Bull. Torrey Club 36: 106. 1909. 



Type locality: Kingston, Sierra County, New Mexico. Type collected by 

 Metcalfe, May 25, 1904. 

 Range: Western New Mexico and adjacent Arizona. 

 New Mexico: Kingston; south of Rito Quemado. 



11. CROTON L. 



Herbaceous or woody annuals or perennials, more or less stellate-pubescent, with 

 alternate simple entire leaves and inconspicuous monoecious or dioecious flowers, 

 these in axillary or terminal, spicate or racemose clusters, sometimes crowded; stami- 

 nate flowers uppermost; sepals 4 to 6, usually 5; petals mostly present but small, 

 alternating with glands; stamens 5 or more; pistillate flowers usually loosely clustered ; 

 their sepals 5 to 10, the petals usually wanting; stigmas much divided; capsule 

 3-celled, splitting into 2-valved carpels each containing 1 seed. 



key to the species 

 Annuals. 



Plants stellate-pubescent throughout, grayish 1. C. texensis. 



Plants glabrous, bright yellowish green 2. C. luteovirens. 



Perennials. 



Low shrub with cordate or subcordate leaves 3. C. fruticulostis. 



Herbs, sometimes suffrutescent near the base, the leaves 

 never cordate, mbstly oval or oblong, rounded at the 

 base. 

 Stami nate flowers petaliferous. 



Leaves gray on both surfaces, the upper ones obtuse . 4. C. corymb ulosus. 



Leaves green above, the upper ones acute 5. C. eremophilus. 



Staminate flowers apetalous. 



Plants loosely stellate-pubescent, not silvery 6. C. tenuis. 



Plants densely lepidote-stellate, silvery 7. C. neomexicanus. 



1. Croton texensis (Klotzsch) Muell. Arg. in DC. Prodr. IS^: 692. 1866. 

 Hendecandra texensis Klotzsch in "Wiegmann, Archiv Naturg. 7: 252. 1841. 

 Hendecandra multifiora Torr. in Frem. Rep. Exped. Rocky Mount. 96. 1845. 

 Type locality: Texas. 

 Range: Wyoming and Illinois to Arizona and Texas, south into Mexico. 



