156 



The Plant World 



Pinus radiata, popularly known as the Monterey pine, is 

 a tree of considerable interest to the student of plant distribution. 

 It occurs naturally in a zone measuring at most but a few miles 

 in width and extending from near Pescadero in San Mateo 

 county down the coast to San Simeon Bay. It is not entirelv 

 confined to the mainland, for it is also found on the islands of 

 Santa Cruz and Santa Rosa of the Santa Barbaras and on the 

 Island of Guadalupe off the coast of the Peninsula of Lower 

 California. Apparently it meets with the most suitable environ- 

 ment on Monterey Peninsula, where it may be observed in its 

 greatest excellence, a few trees attaining a height of eighty to 

 one hundred feet, and a circumference of sixteen to eighteen feet 



It seems to be a tree well adapted to ornamental planting, 

 and handsome specimens are now to be found in such remote 

 parts of the world as southern Europe, Australia, and Xew Zea- 

 land. Probably no species of pine is more popular along the 

 Pacific Coast than is Pinus radiata; at any rate it has been more 

 widely planted from Vancouver to Los Angeles than has any 

 other member of the genus. 



The distribution of this pine is apparently very intimately 

 related to the influence of precipitation and atmospheric moist- 

 ure, and its adjustment to these conditions is a delicate one. 

 When the Arboretum at Stanford University was established 

 manv of the trees selected were of this species, it being supposed 

 that the conditions of soil, humidity and water supply would 

 not vary so widely from those of its natural home as to seriously 

 influence the growth of the trees in the arboretum. Time has 

 demonstrated this much at least pertaining to the life of the 

 Monterey pine, when grown in the northern part of the Santa 

 Clara valley : when the soil is cultivated and not allowed to run 

 to weeds and grass, the trees do fairly well; and if sufficient water 

 is supplied they may attain to a size and vigor rivaling that of 

 the best specimens in the natural forest. If the trees are allowed 

 to shift for themselves, as they have been largely compelled to do 

 in the arboretum, they manage to make a fair growth for a few 

 vears, but do not begin to thrive as they do under natural con- 

 ditions. 



Like the coast redwood, Pinus radiata is a tree the distribu- 

 tion of which is more or less governed by atmospheric moisture, 

 though just what factor prohibits its appearance nodrth of an 



