266 BOTANICAL GAZETTE [OCTOBER 
pearance of species is observed, and the appearance of new ones 
in their places. 
Under the varying influences of soil, moisture, exposure, wind 
currents,?® and other subtler, and often unrecognizable, causes, 
adjoining zones interpenetrate and overlap each other in a most 
irregular manner. Nevertheless they have a real existence and 
evident boundaries, manifested by the general character of the 
vegetation. The most unobservant quickly notices the change 
from one kind of plant growth to a very different kind, as he 
passes from the Desert to the Nevadan or the Cismontane areas. 
The trained eye of the botanist notes in each the limits of several 
subareas, yet detects in each plants seen also in the others. 
The interrelation of the floras of the several areas is mani- 
fested by the numerous genera which have representative species 
in each. Most of them show, by the larger number of species 
growing in it, the area where the conditions are best suited to 
their development, and, when the preference is well marked, that 
area may be considered the one to which they specially belong. 
Some of the larger of these genera are tabulated below: 
INTERRELATIONS OF GENERA. 
SPECIES AND VARIETIES SpEciES AND VARIETIES 
GENERA 5; GENERA Pai asies hice 
Neve [Cimon Doser Neve: [Cixmor| Desert 
ROME ri paces *3 3 2 RI ea sce econ ates II 29 19 
ee ne 5 I 2 Hosackia ........ 5 19 4 
Astragalus ....... i 6 17 NGOS cise cat hes 3 6 5 : 
he Sr fo) 10 7 Krynitzkia ....... I 6 II 
Calochortus...... I 9 3 Lapis 2.42. .5.; 9 16 3 
ng: TT 23 10 I Mimulus,. <<<. iv.; 10 II = 
Chaenactis ...... 2 4 6 Ola kek cee 4 16 12 
Chorizanthe...... 2 II 6 Plagiobothrys..... I 6 A 
Eriogonum ...... 10 9 20 Pentstemon...... 5 8 6 
Erie 604 | tayo, 2 15 fe) Ranunculus ...... 5 3 0 
While most plants have a definite and often very restricted 
range, others are able to adapt themselves to such various 
environments that their limits are circumscribed by no narrower 
*° The influence of wind currents from the deserts is very potent in disturbing the 
life-zones in the narrow Nevadan belt; and in a similar manner the moist winds from 
the ocean modify the boundaries of the Interior and Coastal subareas. 
geese Een Sper .g 
