May 24 ,1924 Significance of the Southwestern Desert Vegetation 
737 
Less Frequent or Rare 
Achyronychia cooperi Torr. & Gray. 
Anogra caiifornica (S. Wats.) Small. 
Aristida adscensionis L. 
Chaenactis sp. 
Chaenactis fremontii A. Gray. 
Chaenactis carphoclinia A. Gray. 
Chorizanthe corrugata (Torr.) Torr. & 
Gray. 
Chorizanthe rigida (Torr.) Torr. & Gray. 
Coreopsis douglasii (DC.) H. M. Hall. 
Cryptanthe muriculata (A. Gray) 
Greene. 
Eriogonum thurheri Torr. 
Eriogonum inflatum Torr. 
Erodium iexanum A. Gray. 
Eschscholtzia caiifornica Cham. 
Euphorbia sp. 
Hordeum murinum L. 
Layia glandulosa (Hook.) Hook. & Arn. 
Linanthus lemmoni (A. Gray) Greene. 
Lupinus sp. 
Mohavia viscida A. Gray. 
Monoptilon bellioides (A. Gray) Hall. 
Nemoseris caiifornica (Nutt.) Greene. 
Palafoxia linearis Lag. 
Parosela mollis (Benth.) Heller. 
Phacelia sp. 
Phacelia distans Benth. 
Plantago fastigiata Morris. 
Salvia columbariae Benth. 
Sphaerostigma decorticans (Hook. & 
Arn.) Small. 
ANNUAL AND BIENNIAL SPECIES IN THE CREOSOTE BUSH ASSOCIATION IN THE 
GILA VALLEY 
Common or Frequent 
Plantago erecta Morris. 
Festuca octoflora Walt. 
Lepidium lasiocarpum Nutt. 
Pectocarya penicillata (Hook. & Arn.) 
A. DC. 
Baeria chrysostoma Fisch. & Mey. 
Amsinckia menziesii (Lehm.) Nels. & 
Macbr. 
Thelypodium lasiophyllum (Hook. & 
Arn.) Greene. 
Eriodium texanum A. Gray. 
Matricaria matricarioides (Less.) Porter. 
Orthocarpus purpurascens Benth. 
Erodium cicutarium (L.) L’H4r. 
Lesquerella gordoni sessilis S. Wats. 
Allocarya sp. 
Calandrinia caulescens H. B. K. 
Lotus subpinnatus Lag? 
Baeria aristata (Nutt.) Coville. 
Filago arizonica A. Gray? 
Eschscholtzia sp. 
Less Frequent or Rare 
Bowlesia septentrionalis Coult. & Rose. 
Chylisma scapoidea (Nutt.) Small. 
Conanthus demissus (A. Gray) Heller. 
Daucus pusillus Michx.? 
Dr aba cuneifolia Nutt. 
Evax multicaulis D. C. 
Gaillardia arizonica A. Gray. 
Eschscholtzia caiifornica Cham. 
Linaria canadensis (L.) Dumort. 
Lupinus sp. 
Lupinus arizonicus S. Wats. 
Monolepis nuttaXliana (Schutt.) Greene. 
Pachylophust 
Plagiobothrys arizonicus (A. Gray) 
Greene. 
Plantago fastigiata Morris. 
Poa bigelovii Vasey & Scribn. 
Salvia columbariae Benth. 
Silene antirrhina L. 
APPEARANCE 
Normally the creosote bush is a dark brownish-green shrub about 5 feet high 
(PI. 3, B and 4, A.) It divides at the surface of the ground into several main 
branches, which branch again sparingly, giving the appearance of an open bush. 
The dark brownish-green color is due to the thick resin-covered leaves, which are 
in pairs and occur most abundantly on the young twigs. In the spring these 
twigs bear numerous small bright yellow flowers. Pure areas of creosote bush 
