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AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
situations, but ranged east to the Great Plains. Malva parviflora occurred 
rarely as a weed in towns. Disella lepidota was common along the Rio 
Grande in the Big Bend. Disella hederacea was common in somewhat alka- 
line soil along the Rio Grande at El Paso and at Indio in the Big Bend. 
Sida hastata occurred generally but not abundantly in valleys throughout 
the region. S. diffusa and S. filiformis were common in their usual wide 
range of habitats. Gayoides crispum was found frequently on rocky slopes 
in the Big Bend and in the Davis Mountains. Sphaeralcea cuspidata was 
found abundantly in the Rio Grande Valley from Boquillas to El Paso, 
and infrequently in the valleys to the north. S. lohata was abundant in 
rocky and sandy soil near El Paso, and rare at Ruidosa in the Big Bend. 
S. incana was rare below 4,000 feet, but it was seen in sandy soil near the 
Rio Grande at El Paso. 5. suhhastata was rare at the base of mountain 
slopes in sandy clay soil at Shafter and Sierra Blanca. 5. tenuipes was 
found in abundance on rocky mountain sides at El Paso and Sierra Blanca. 
Sida longipes was rare on rocky mountain sides near Sanderson. S. tragiae- 
folia was common in rocky valleys at Boquillas. 
IV. The Upper Sonoran 
The higher portions of the Great Plains, already discussed under the 
Lower Sonoran, are included in the Upper Sonoran. As very little of the 
Upper Sonoran plains were scouted, this area is not treated in detail. The 
Trans-Pecos Plateau and Mountains above 4,000 feet are included in the 
Upper Sonoran. The physiography, climate, and vegetation of this area 
were described in the preceding section. 
Hibiscus denudatus var. involucellatus , H. couUeri, Ahutilon incanum, A. 
malacum, A. wrightii, A. parvulum, Gayoides crispum, Sphaeralcea cuspidata, 
S. lohata, S. incana, Sida hastata, S. diffusa, and S. filiformis were found in 
this zone in locations as described in the preceding section. Wissadula 
holosericea was frequent on rocky slopes near Balmorhea, in the Davis 
Mountains, and near Alpine. Sphaeralcea tenuipes was abundant on the 
mountain sides near El Paso. S. pumila was frequent in sandy soil on 
lower mountain slopes near the lower limit of this zone at El Paso. Mai- 
vastrum elatum occurred frequently in sandy and rocky soil from Alpine and 
the Davis Mountains to El Paso. M. coccineum was rare on the sandy plain 
near Alpine. A few plants of Disella sagittaefolia were found as weeds in a 
yard at Alpine. Sida tragiaefolia was rare on rocky slopes near Alpine. 
S. longipes was rare on rocky slopes from Sanderson to Marathon. S. 
neomexicana was frequent on rocky slopes near Limpia Canyon in the 
Davis Mountains. 
