VEGETATION OF THE SANTA CATALINA MOUNTAINS. 19 
Ephemeral Summer-active Herbaceous Plants—Continued. 
Root Perennials (all facultative evergreens): Ephemeral Summer-active Herbaceaus Plants: 
** Abutilon incanum, sclerophyllous. Continued. 
** Brodiea capitata var. pauciflora, *** Pectis papposa. 
bulbous, linear leaves, *** Wedelia incarnata. 
** Cassia covesii,sclerophyllous,branched | Ephemeral Winter-active Herbaceous Plants. 
leaves. ** Actinolepis lanosa. 
* Dalea parryi, microphyllous. ** Anisolotus trispermus. 
*** Muhlenbergia porteri, semi-scandent. *** Baeria chrysostoma. 
** Pentstemon wrightii, macrophyllous. ** Chorizanthe brevicornu. 
** Perezia wrightii, macrophyllous. ** Cryptanthe intermedia. 
** Verbena ciliata, macrophyllous, hairy. * Bremocarya micrantha. 
Ephemeral Summer-active Herbaceous Plants: *** Gilia floccosa. 
** Bahia absinthifolia. ** Lepidium lasiocarpum. 
*** Baileya multiradiata. ** Lesquerella gordont. 
** Boerhaavia pterocarpa. * Menizelia albicaulis. 
* Boerhaavia watsoni. * Orthocarpus purpurascens. 
*** Bouteloua aristidoides. ** Pectocarya linearis. 
*** Cladothriz lanuginosa. *** Plantago fastigiata. 
** Huphorbia florida. *** Plantago ignota. 
* Huphorbia melanadenia. 
THE DESERT ARROYOS AND CANONS. 
In crossing the Upper Bajadas it is often possible to detect, by means 
of the vegetation, the approach to a very shallow drainageway through 
which water runs for only a few hours after the severest summer rains. 
The larger arroyos are still more conspicuous by reason of the still 
heavier stand of vegetation along their margins, and in the largest 
cafions is found the culmination of the influence of surface streams 
and underflows for the support of vegetation. The effect of the most 
transitory of the small streams is merely the raising of the moisture of 
adjacent soil to such a point that it will present favorable conditions 
for plant activity for a longer time after the close of the rainy periods 
than will the soil of the bajada in general. There is only a negligible 
and short-lived underflow in these smallest arroyos, and their only 
differences from the bajada are that in the rainy seasons they present 
slightly more favorable conditions with respect to soil moisture and 
that the effect of the rainy season is slightly prolonged in them, while 
the periods of drought are correspondingly shortened. In the larger 
arroyos there may not be a constant underflow, but there is at least a 
relatively high percentage of soil moisture for periods of sufficient length 
to greatly reduce the influence of the arid periods upon their plants. 
In the largest arroyos and in the mountain cafions themselves there is 
either a constant underflow, maintaining high moistures in the.soil of 
the banks and bed of the arroyo, or else there is constant water, either 
running or standing in pools. 
The smallest arroyos, which are very frequent on the Upper Bajada 
in the close proximity of the mountain, present no peculiar species, but 
merely a closer stand of the same plants that are to be observed 
throughout the bajada, notably Prosopis, Acacia greggii, and Momisia 
pallida. Along somewhat larger arroyos are to be found still heavier 
stands of the above species, together with Parkinsonia torreyana, Celtis 
