No. 400.] ZONES IN ARIZONA AND NEW MEXICO. 29I 
(2) Representative Species similar to, but not identical with, those 
of the Mesilla Valley. 
PLANTS. 
Spheralcea variabilis n. sp. — The common perennial Spheralcea of the 
alt River Valley, which at first sight might be taken for S. /oóata 
Wooton, pines common in the Mesilla Valley. The leaves vary from 
IX to over 3 inches long, and resemble in shape those of lobata, being 
quite long, with obtuse lateral lobes ; but they average broader, are some- 
what more regularly and finely crenulate, or the margins almost entire, 
and the living leaves have the surface, and especially the margins, much 
more wrinkled. The difference between the plants, as seen living, is 
sufficient to strike the eye, but it is a difference in average rather than 
absolute characters. There is, however, one character of greater value ; 
the carpels of lobata are conspicuously cuspidate, whereas in variabilis 
they are rounded at the top, and bear no cusps. It may therefore be 
said that variabilis resembles lobata in its leaves, but angustifolia rather 
in its fruit. The basal portion of the carpels is very strongly reticulated, 
as in lobata. The flowers are as in lobata. This plant is here called 
ecies, being about as distinct as the other members of its series — 
angustifolia, lobata, and fendleri; but it would be possible to regard 
variabilis as a race of lobata, or both as races of fendleri 
SS. variabilis was found freely blooming about phali in October. 
It is not so tall a plant, on the average, as S. dodata. 
Jsocoma acradenia (Greene) Greene. — This is the common Bigelovia of 
the vicinity of Phoenix, exactly occupying the place taken in the Mesilla 
Valley by Z. heterophylla wrightii. I had confused the Phoenix plant 
with Z. hartweg?, but I found the real hartwegi (certified as such by Dr. 
Greene) abundant at Tucson, taking the place of acradenia. Z. acra- 
denia has the flowers of hartwegi, with the foliage (only smaller) of 
_ heterophylla wrightii. 
Cucurbita palmata Watson.— Common in the Salt River Valley, taking 
the place of the Mesilla Valley C. fetidissima. 
Prosopis velutina Wooton. — The mesquite of Arizona, found at Phoenix, 
Mesa, Buckeye, Tucson, etc., is distinct from P. glandulosa Torrey, the 
mesquite of the Mesilla Valley. 
Acacia greggii Gray. — Abundant in the Salt River Valley ; much larger 
than the species of the Mesilla Valley. 
Echinocactus lecontei (Engelm.) Toumey. — This barrel cactus takes the 
place of the Mesilla Valley Æ. wislizeni Engelm.; the latter, however, 
occurs at Tucson. Æ. /econtei is usually considered a variety of E. 
wislizeni, but when I saw it, it seemed to me distinct, and Professor 
Toumey tells me that it is a valid species. 
