94 



The Garden Magazine, October, 1919 



WE ARE not here concerned with the theories as to 

 what particular astronomical changes induced the ice 

 age; but it is important to realize that the ice did not descend 

 to equal latitudes all round the Northern Hemisphere. 

 Japan and China proper escaped glaciation and though the 

 temperature must have been lowered, their vegetation suf- 

 fered little harm. Of course there was a migration toward 

 the south, and a reverse one at the close of the glacial epoch. 

 The net result is that the flora of the Chinese Empire, and 

 of Central Japan southward is to-day really an epitome of 

 the world's flora of the Northern Hemisphere in preglacial 

 times. 



In China and in the parts of Japan indicated are growing 

 to-day many peculiar types as well as all the principal 

 known genera of trees from the other parts of the Northern 

 Hemisphere — except Robinia, Laburnum, Platanus, True 

 Cedars (Cedrus), Sequoia and Taxodium. And of the latter 

 there are two very closely allied — Taiwania andGlyptostrobus. 

 Fossils occur in Europe of many types which grow in the 

 Orient to-day and recent dredging off the Dutch-English 

 coast has added much to prove that the past flora of Europe 

 was similiar to that of the Far East to-day. I mean, of 

 course, not specifically but that the generic types were much 

 the same. If we picture to ourselves the onward, in- 

 evitable creeping southward of the ice, we can easily under- 

 stand how trees and other forms of vegetation in its path 

 were destroyed. Only those which were able to reach places 

 of sufficient warmth to maintain 

 life, survived. The greater the 

 land extension toward the south 

 the greater chance had vegeta- 

 tion; likewise where the country 

 was broken by mountain ranges, 

 advantageous regions were more 

 easily found. 



The ice in its progress ground 

 off the tops of mountains and 

 scoured out valleys to a great 

 depth; and when it retreated 

 the face of much of the North- 

 ern Hemisphere was changed. 

 It disappeared from sea-level 

 valleys earlier than from moun- 

 tain ranges, and so isolated 

 groups of vegetation. If we pic- 

 ture this, and remember that 

 before the period of great cold 

 set in the vegetation of the 

 North was everywhere very 

 similar, we readily understand 

 how to-day are found here and 

 there, groups of trees isolated 

 by thousands of miles from their 

 kindred. It is this that explains 

 the separation of the Cedars of 

 Lebanon, of the Taurus, Cyprus, 

 the Atlas Mountains and of the 

 Western Himalayas, and also 

 the isolation of the Nettle Tree, 

 Honey-locust, Sweet Gum, 

 Walnut and others in the Cau- 



A FAMOUS SASSAFRAS AT WESTFORD, MASSACHUSETTS 

 Never so huge nor patriarchal as individuals but of pe- 

 culiar appeal as one of the two survivors of its waning 

 kind is our native "mitten-leaf." (Sassafras officinalis) 



casus region, in eastern North America and in the Orient. 

 What were temperate regions of the North during Tertiary 

 times are to-day the frozen North, and the land of this 

 region capable of growing forests is infinitely less than it 

 was then. 



Deserts, seas, lakes, high plateaux and mountain ranges 

 influence climate and therefore strongly affect plant dis- 

 tribution. Birds, animals, and air and water currents are 

 all agencies in plant dispersal. Hence to understand why 

 this tree or the next is here and not yonder, involves the 

 study of a number of cognate branches of natural history. 

 Complex indeed is the problem ; but however little it is studied 

 the marvels of the world we live in become more and more 

 apparent. 



BRIEF and fragmentary as this sketch is, it would be more 

 incomplete without mention of the influence of man. At 

 what period in the world's history he first appeared in his 

 present form is much disputed; but certain it is that as soon 

 as he became a reasoning creature, hunger led him to investi- 

 gate the vegetation and taught him to appreciate what was 

 wholesome as food. As he migrated we know that he carried 

 with him the plants that were of service to his needs — and 

 later such as were a delight to his higher being. But we 

 know so little of the early peregrinations of the human race, 

 or of where it had its cradle, that we can say nothing definite 

 of that remote and most interesting period. In the mytho- 

 logy, folk-lore, and sacred writ- 

 ings of all races of which we 

 have knowledge, frequent men- 

 tion of trees is made, and in- 

 vading armies devastated coun- 

 tries and carried off useful 

 plants, fruits, trees and the like, 

 as spoils of war. Alexander 

 the Great is himself but a 

 name in history in spite of his 

 great conquests — yet a perma- 

 nent beneficial result of these 

 conquests remaining to man- 

 kind are the Oranges his sol- 

 diers are said to have carried 

 back from India to the shores 

 of the Mediterranean. 



OF THE mighty migrations 

 across Asia we know very 

 little, though it is certain that 

 for centuries the great highways 

 of commerce of the Old World 

 were across Central Asia. That 

 the peach and the orange and 

 certain of its relatives were 

 carried from China to Persia 

 and that neighborhood is cer- 

 tain; and that the walnut and 

 grape were brought back is 

 equally true. Possibly the apri- 

 cot came with the latter. From 

 the rich and famed China of 

 old, plants useful and ornamen- 



