THE AMERICAN BOTANIST 71 



the quality of a seed for a part of every seed may be unsound, 

 and sometimes the larger part as in the case of the tulip tree; 

 second the difficulty of disseminating, particularly of heavy 

 seeds as walnut, etc.; tliird. the carrying of seeds to surround- 

 ings detrimental to successful germination, for instance seeds 

 requiring moist soil may lodge upon dry ground, etc. ; fourth, 

 the period before a tree can produce seed, as in the case of the 

 white oak. which does not produce any until it is forty years 

 old ; and fifth, the time elapsing between seed years — trees 

 bearing seeds only e\-ery three or four years according to spe- 

 cies, habitat, etc. 



After a successful start seedlings often perish in the 

 flames of destructive fires, under the feet of grazing cattle or 

 in the litter of the forest floor, which their tender roots are un- 

 able to penetrate in their effort to gain the fertile soil beneath. 

 The infant tree, the result of a succssful seedling may decay 

 for want of proper light, watei or soil, for the trees in a forest 

 are engaged in a constant itruggle — tree against tree — for 

 these essentials and the tree that receives too little or too much 

 of any of them is bound to suffer if not to die. Each tree, 

 therefore, to gain these necessities in the proper proportions 

 adapts the manner of its growth and the shape of its branches 

 and leaves; and for this reason we never see two trees exactly 

 alike. However, it is advantageous for each tree at first, that 

 it may receive enough light, to effect by self pruning a bail 

 straight shaft, so that by dropping the lower branches it may 

 expend all its energy in the spreading of its head and trunk. 



Even if a seedling does overcome the obstacles outlined 

 in the preceding paragraph, and develops into a healthy tree 

 with a broad straight trunk and full crown, the battle is not 

 yet won for there are still many enemies to conquer. We may 

 ask : What enemies has the forest ? And the answer is the 

 physical forces of nature, plants, animals and man. Nature, 

 in the form of wind, snow, ice, floods, landslides and lightning 



