CUCUMBER-TREE 



else, and so escape unfavorable conditions. There is a natu- 

 ral climatic belt to which the life of a forest is adjusted. In 

 the present instance, as the favorable conditions near the 

 poles were disturbed by the cooling influences of the glacier 

 approaching from the north, the individual trees on that side 

 of the forest belt gradually perished ; but at the same time 

 that the favorable conditions of life were contracting on the 

 north, they were expanding on the south, so that along the 

 southern belt the trees could gradually advance into new 

 territory, and so the whole forest belt move southward, fol- 

 lowing the conditions favorable to its existence. It is there- 

 fore easy to conceive how, with the slow advance of the gla- 

 cial conditions from the north, the vegetation of Greenland 

 and British America was transferred far down toward the 

 torrid zone on both the Eastern and Western continent. 

 Being thus transferred, the forest would be compelled to re- 

 main there until the retreat of the ice began again to modify 

 the conditions so as to compel a corresponding retreat of 

 plants toward their original northern habitat. Thus it is that 

 these descendants of the pre-glacial plants of Greenland, ar- 

 rested in their northward march, have remained the character- 

 istic flora of the latitudes near the glacial boundary." 



CUCUMBER-TREE. MOUNTAIN MAGNOLIA 



Magnolia acuminata. 



Acuminata refers to the pointed apex of the leaves. 



Of two forms ; in the forest it rises to the height of ninety feet 

 with sturdy unbroken trunk for two-thirds its height ; when allowed 

 sufficient space to develop, it becomes a cone with branches that 

 sweep the ground. Prefers a moist, fertile soil, but will grow on 

 rocky river-banks. Roots fleshy. Ranges from western New York 

 to southern Illinois, south through central Kentucky and Tennessee 

 to Alabama, and throughout Arkansas. 



.5ar^.— Brown, regularly furrowed and scaly. Branchlets slender, 

 red brown, downy, later becoming gray. 



9 



