Published by the Lorquin Natural History Club 
(Organized— August 1913) 
Number 11 LoS AngelcS, Cal., June 1917 |i*'per Year 
THE DISCONTINUOUS DISTRIBUTION OF SOME 
PLANTS 
By Fordyce Grinnell, Jr. 
A study of the present habitats of hving things may tell us many 
facts concerning their past history and migrations. We may learn 
that the earth has undergone marked changes in its climatic or geo- 
logical history. Those plants or animals of which we have only a 
few related forms scattered at remote and restricted regions of the 
earth are especially suggestive of an old geologic history ; and a great 
change geologically or climatically to explain their present where- 
abouts. A good example of discontinuously distributed plants is 
found in the four species of the curious coniferous tree Tiimion or 
Torreya. Tumion taxifoliuiu is found in the extreme southeastern 
United States ; T. calif orniciim in the middle mountain region of 
California — the Coast Range and Sierras ; T. nudiferiim in southern 
Japan ; and T. grande in northern China or Mongolia. In past geo- 
logical time there were many species of Sequoia scattered pretty con- 
tinuously over the northern hemisphere, but now there are only two 
survivors, found each in a limited region in California ; one in the 
Coast Range and the other in the Sierras. 
Here in Southern California we have a number of isolated plants 
which we do not meet with for long distances ; they indicate, as a 
rule, a change in climatic or geologic history, or, in one, a possible 
planting of the seed by wind or birds. Of course there may be other 
and unknown factors. These discontinuously distributed plants were 
doubtless at one time continuously distributed between their present 
extreme living representatives ; and in the case of one, as the Sequoia, 
between their present survivors and their fossil remains in Alaska, 
Greenland and other regions. 
The following local plants are a few of the more interesting and 
striking examples to a student and should be made, together with other 
plants, subjects of individual thought and study. 
1. Pinus monophylla Torr. & Frem. Nut Pine or Single-leaf 
Pine. One good-sized tree is found on the summit of Mt. Lowe. It 
has been found on no other portion of the front range of the San 
Gabriel mountains, but is abundant on the desert slopes. 
