470 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM [1885. 



The vegetation is that peculiar to the great Texano-Mexican Desert. 

 The sparse trees are confined to the alluvial bottom and dependent 

 ravines ; they are Cottonwood, Hackberry, Mesquite, Screw Bean and 

 Willow (Salix longifolia and nigra). Shrubs and bushes are common 

 enough, but in scattered thickets nowhere forming a dense chaparral ; 

 those preponderating on mesas aud hills are : 



Acacia Greggii and constricta. 



Mimosa borealis and biuncifera. 



Dalea formosa. 



Condalia obovata and spathulata. 



Zizyphus obtusifolius. 



Kceberlinia spinosa. 



Celtis pallida. 



Lycium Carolinianum, Berlandicri, puberulum. 



Mozinna spathulata. 



Ephedra antisyphilitica and trifurca. 



•Larrea Mexicana. 



Flour ensia cernua. 



Yucca angustifolia. 

 The Palmo (Yucca baccata, var. australis), with tall caudex, 10 to 20 

 feet high and 1 to 2 feet in diameter, covers the broad graded incline 

 extending from the valley to the Chenate Mountains. The obnoxious 

 Lechuguilla (Agave heteracantha) is everywhere but too common. The 

 Bear-Grass or Sotol (Dasylirion Texanum) is also conspicuous, Of the 

 abundant Cacti the most remarkable species are: Anhelonia Jissurata 

 (Pellote) bearing a beautiful flower and used medicinally by Mexicans ; 

 Anhelonia Williamsii not before observed on this side of the Rio Grande ; 

 Cereus Greggii, one of the most ornamental of its class ; ' Cereus stramineus 

 (Strawberry Cactus) with large, red, delicious fruit." 

 The bottom is covered with such weeds as — 



Nama hispidum. 



Solarium nigrum and elo3agnifolium. 



Portulaca oleracea, retusa, lanceolata. 



Petunia parviflora. 



Sida hederacea. 



Cucurbita perennis. 



Lippia nodiflora. 



Tribulus maximus. 



Rumex Berlandieri. 

 And also the following Composites : 



Helianthus lenticularis and ciliaris. 



Verbesina encelioides. 



Aster spinosus, tanacetifolius and canescens. 



Coreopsis cardaminefolia. 



Aplopappus spinulosus. 



Gutierrezia Texana. 



Helenium amphibolum. 



