12 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 
“The leaves of the creosote bush are so wholly on its outer surface that it would be 
quite easy to shear them all off, as one shears a sheep, and leave the bush nearly full 
size but perfectly bare. The usual height of this bush is from two to three feet. The 
clumps stand about ten feet apart, and usually there are from 100 to 150 peracre. In 
a few localities we saw some very large specimens, which grew fully ten feet in height.”” 
Kallstroemia grandiflora Torr.; A. Gray, Smiths. Contr. Knowl. 3: 28. 1852. 
Type locality, ‘‘ Borders of the Gila,” New Mexico or Arizona. 
MacDougal Crater, Pinacate Mountains, November 14, 1907, MacDougal 25. 
Chamaesyce pediculifera (Engelm.) Rose & Standley. 
Euphorbia pediculifera Engelm. in Torr. Bot. Mex. Bound, 186. 1859. 
Type locality, ‘‘Sonora.” 
Quitovaquito, Sonora, November 11, 1907, MacDougal 17; MacDougal Crater, Pin- 
acate Mountains, November 14, 1907, Sykes 28. 
Croton arenicola Rose & Standley, sp. nov. 
Low shrub, less than a meter high, much branched, the stems strictly erect, whitish, 
slender, densely lepidote throughout; leaves linear to linear-oblong or lanceolate, 20 to 
35 mm. long, 2 to 6 mm. wide, rounded at the apex, attenuate to the base, densely 
lepidote-stellate on both surfaces, whitish, on slender petioles 5 to 14 mm. long; flowers 
dicecious, both kinds apetalous; staminate flowers in few-flowered racemes 15 to 30 
mm. long, naked below, the calyx lobes ovate, densely stellate and lepidote, obtuse, 
the flowers 4 mm. broad, on pedicels 5 to 8 mm. long; stamens slightly exceeding the 
sepals; pistillate raceme about 3 cm. long, sometimes less, the flowers on stout pedicels 
4 to 6 mm. long, the calyx lobes ovate, obtuse; capsule 10 or 11 mm. high, densely and 
finely stellate and somewhat lepidote; seeds oval or oblong, 7 or 8 mm. long, variegated 
with brown and gray, the caruncle stipitate, small. 
Type in the U. 8. National Herbarium, no. 574267, collected on sand hills about 
Adair Bay, Gulf of California, in northwestern Sonora, November 20, 1908, by Mr. G. 
Sykes (no. 62). , 
This is near Croton tenuis but has more abundant pubescence so that the plant 
appears silvery throughout; the leaves are also narrower, and the seeds are much 
larger with a different caruncle. 
Ditaxis odontophylla Rose & Standley, sp. nov. 
Low, 20 cm. high or less, erect or ascending; stems stout, pilose; leaves oblanceolate, 
attenuate at the base into a short petiole, rather thin, bright green, more or less pilose 
on both surfaces, broadly obtuse and coarsely dentate near the apex; staminate flowers 
with linear-oblong sepals and oval, clawed petals, the latter white tinged with purple 
near the base, the sepals pilose; pistillate flowers with linear-lanceolate, hirsute sepals, 
the style tips not enlarged; capsule strongly hirsute; seeds subspherical, smooth, 
brown. 
Type in the U. 8. National Herbarium, no. 574248, collected at the Papago Tanks, 
Sonora, November 14, 1908, by Dr. D. T. MacDougal (no. 36). 
The plant is similar to Ditaris neomexicana but has very different leaves and much 
more abundant pubescence. 
Here may be inserted a description of another apparently new 
species of Ditaxis, detected while attempting to determine Ditaxis 
odontophylla. 
Diraxis Gractuis Rose & Standley, sp. nov. 
Low, sparingly branched, slender annual, 30 to 40 cm. high; stems sparingly pilose, 
pale green; leaves lanceolate or elliptic-lanceolate, 5 to 6 cm. long and 20 to 25 mm. 
wide, acute, somewhat attenuate at the base, thin, bright green, all except the 
youngest glabrous, all on slender petioles 10 to 18 mm. long; racemes few-flowered and 
