18 VEGETATION OF A DESERT MOUNTAIN RANGE. 
Bajadas in seasons of well-distributed and copious rainfall. With less 
favorable conditions they may form a very light cover or may be almost 
absent. The total flora of root-perennials and ephemerals is large, and 
the relative abundance of the various species fluctuates tremendously 
from spot to spot, and in the same spot it is by no means the same from 
year to year. This flora is nearly identical with that of the basaltic hills 
in the vicinity of Tucson, and has been fully listed by Thornber,* with 
a subdivision of vegetation types. 
In the following list have been brought together the names of the 
most characteristic plants of the Upper Bajadas, grouped vegetistically 
and briefly described. Asterisks indicate the relative abundance of 
the species—three indicating that a plant is extremely common, two 
that it is very common, and one that it is fairly common. Figures 
follow the descriptions, indicating the average height of each species. 
A comparison of all the maximum heights given will convey an impres- 
sion of the low stature of the commonest components of the vegetation. 
Vegetistic Grouping of the Characteristic Species of the Upper Bajadas. 
Perennial Non-succulent Trees and Shrubs: 
**#* Acacia greggti, microphyllous, winter- 
deciduous. 2 to 3m. 
** Covillea tridentata, microphyllous, 
evergreen. 1 to 2.5m. 
* Crossosoma bigelovii, sclerophyllous, 
evergreen. 1 to 1.5m. 
* Ephedra trifurca, aphyllous, green- 
stemmed. 0.5 to 1m. 
*** Fouquieria splendens, macrophyllous, 
drought-deciduous. 2 to 4m. 
** Jatropha cardiophylla, macrophyllous, 
winter-deciduous. 0.5 to 1m. 
* Keberlinia spinosa, aphyllous, green- 
stemmed. 0.5 to 1m. 
** Krameria glandulosa, microphyllous, 
evergreen. 1 to 2m. 
** Tycium berlandieri, microphyllous, 
evergreen. 1 to 2m. 
* Lycium fremontii, microphyllous, 
evergreen. 1 to 2m. 
** Momisia pallida, sclerophyllous, ever- 
green. 1.5 to 2.5m. 
* Olneya tesola, microphyllous, ever- 
green (foliage occasionally winter- 
killed). 3to6m. 
*** Porkinsonia microphylla, microphyl- 
lous, drought-deciduous, green- 
stemmed. 2 to 5m. 
*** Prosopis velutina, microphyllous, 
winter-deciduous. 3 to 6m. 
** Zizyphus lycioides var. canescens, 
microphyllous, evergreen 1 to 2 m. 
Perennial Succulent Plants: 
*** Carnegiea gigantea, columnar, 
branched. 5 to 14 m. 
** Echinocactus wislizent, cylindrical. 
0.5 to 1.5 m. 
** Fchinocereus fendleri, cylindrical, cz- 
spitose. 0.1 to 0.4 m. 
** Mamillaria grahami, cylindrical, soli- 
tary or cxspitose. 0.1 to 0.2m. 
** Opuntia blakeana, flat-jointed, pro- 
cumbent. 
*** Opuntia discata, flat-jointed, pro- 
cumbent or semi-erect. 
** Opuntia fulgida, cylindrical-jointed, 
arborescent, 1 to 2 m. 
*** Opuntia mamillata, _cylindrical- 
jointed, arborescent. 1 to 2m. 
** Opuntia toumeyi, flat-jointed, pro- 
cumbent. 
*** Opuntia versicolor, cylindrical-jointed, 
arborescent. 1 to 4m. 
Perennial Shrublets (all less than 0.7 m. high): 
* Coldenia canescens, sclerophyllous. 
** Crassina pumila, dissected leaves. 
*** Encelia farinosa, macrophyllous, 
slightly drought-deciduous. 
*** Franseria deltoidea, sclerophyllous. 
*** Tsocoma hartwegi, dissected leaves. 
*** Kalliandra eriophylla, dissected leaves. 
** Psilostrophe cooperi, sclerophyllous. 
* Trizis angustifolia var. latiuscula, 
sclerophyllous, slightly drought- 
deciduous, 
* Thornber, J. J. Vegetation Groups of the Desert Laboratory Domain. Carnegie Inst. 
Wash. Pub. 113, Chapter IV, 1909. 
