36 Botany of Mariposa. [ZOE 
Hordeum murinum L. P. C. 
_ Elymus condensatus Presl.  C. 
wimnicas LG, S, 
Sitanion Schult. P. C. 
Polypodium vulgare L. C. S. 
Gymnogramme triangularis Kaulf. C. S. 
Pellaza andromedefolia Fee. C. 
Ornithopus Hook. C. 
Pteris aquilina L. C. 
Woodwartdia radicans Sm. C. 
Aspidium rigidum Sm. C. S. 
munitum Kaulf. C. 
Cystopteris fragilis Bernhardi. C. S. 
Selaginella rupestris Spreng. C. S. 
Azolla Caroliniana Willd. P. 
This list shows that out of 318 native species common to this dis- 
trict and the coast, as above defined, only 105, or about one-third, 
are found in the intervening plain. It is possible, but not probable, 
that a more thorough exploration of the plains would add something 
to the number of the species found there, but could hardly produce 
any serious change in the ratio. On the other hand, out of the 66 
naturalized plants enumerated, 59 are pretty certainly found on the 
plains, showing that they have accompanied the successive waves of 
immigration which first swept over the foothills in the search for 
gold, but have now largely flowed back upon the plains, seeking 
the agricultural treasures of the soil, 
A further examination of the same list shows how rapidly the 
plants of the plains and lower foothills disappear as we ascend into 
mountains. Of the 105 plants of the plains found in this zone, only 
37 reach the coniferous belt and only three the subalpine district. 
Probably there are really only two of these, as Achillea millefolium 
is pretty certainly naturalized on the plains, having been introduced 
with grass seed. Out of the 21 3 remaining species 115 extend into 
the coniferous belt, of which 27 reach the subalpine region. Two 
of these, Dodecatheon Meadia and LEviophyllum cespitosum, attain 
the alpine summits in some of their varieties which, however, may 
yet be specifically distinguished from the lower forms. 
: Coming now to the species really characteristic of or limited to 
