484 POPULAR SCIENCE MONTHLY. 



two miles long and two or three hundred yards wide, and over a still 

 smaller area a little farther south. The California fan-palm only oc- 

 curs in a few canyons of two mountain ranges in the southern part of 

 the state. The western hop hornbeam is only known to grow over a 

 few square rods of territory in the Grand Canyon of the Colorado river 

 in Northern Arizona. In eastern United States, Torreya only grows in 

 a narrow strip on the eastern bank of the Appalachicola Eiver in 

 Florida : while the Florida yew, which grows in the same region, occu- 

 pies a still less extended area. 



In such cases as these it is likely that the structural and physiologic- 

 al adaptions of the different plant organs have not kept pace with the 

 natural changes in environment. As a result, these trees are not only 

 unable to extend their present range, but are poorly fitted to persist 

 where they now grow and consequently are disappearing. These old 

 types of trees have in the course of ages become inflexible and fixed and 

 are no longer in perfect accord with their environment. More modern 

 types, as illustrated in the various genera of Cactaceae, are more general- 

 ized and very readily take on structural and physiological modifica- 

 tions which fit them better to their present environment. It is inter- 

 esting to note that many of the species which appear to be out of accord 

 with their natural environment often do well under cultivation. The 

 gardener's care in subjecting them to different environmental condi- 

 tions, particularly as regards food supply, seems to stimulate them and 

 give them new vitality, thus causing them to succeed better than more 

 modern types perfectly in accord with their natural environment. In 

 the latter case overstimulation, induced by cultivation, may from the 

 standpoint of vitality do more harm than good. 



The Monterey cypress, although now nearly extinct as a wild plant, 

 is one of the most successful and easily cultivated trees of the Southwest. 

 It appears to be far better in accord with the artificial environment in- 

 duced by cultivation than it is with its natural environment. The 

 Franklinia of our gardens, a small tree first collected by John Bartram 

 in 1765 on the banks of the Altamaha Eiver in Georgia, is successful in 

 cultivation, although as a wild plant it passed out of existence during 

 the past century. It is far more successful in cultivation than the 

 Loblolly bay, an allied species of the same genus which is now growing 

 wild from Virginia to Florida. The Ginkgo, an Asiatic tree of ancient 

 origin, grows remarkably well in cultivation, although at the present 

 time it is not known to grow as a wild plant any where. 



Modern plant types that have not yet reached the limits of their 

 distribution and variation, as illustrated in many species of the Com- 

 positae, Eosaceae and Cactaceae, are so nicely adjusted to their natural 

 environment that cultivation often tends to diminish their vitality 

 rather than improve it. 



