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plete possession of the habitat. Shade conditions are such as to exclude 

 light-demanding forms. First attempts at photography under the arbor 

 vitaes resulted in failures, on account of uniform under exposures. The 

 vegetation of the forest floor is not abundant, except in early spring. The 

 herbs are largely shade-enduring species. The mat of roots and fallen 

 branches and leaves is another factor that deters invasion from without. 

 If the toxicity of the substratum is a factor, it exerts its maximum influence 

 here, under present conditions. Then, too, the plants of the association are 

 reproducing themselves very efficiently, all stages of seedlings and saplings 

 being found. Nearly all the Thuyas germinate on stumps and logs. A 

 specimen four or five inches in diameter and twenty-five feet in height was 

 found growing on a stump four feet high. Even the oldest trees, wbich must 

 be hundreds of years old, are still grasping in their roots the partially decayed 

 remains of the logs upon which they germinated. The fact that the logs 

 are lying in a position that subjects them to the greatest exposure to decay 

 shows the resistant qualities of arbor vitae wood. The logs shown in the 

 photograph (Fig. 4) are still fairly sound, though the trees which grew upon 

 them are two feet in diameter. 



One of the commonest undergrowth shrubs is Taxus canadensis, which is 

 here a prostrate, creeping shrub, seldom more than one or two feet in height. 

 No traces of seed formation were observed, but the plant reproduces abundantly 

 by layering. What at first glance seems to be a group of plants is found 

 to be a series of layered branches from a common central plant. This habit 

 is of considerable ecological importance here, since it seems to be the only 

 means of reproduction of the species. 



As the accompanying list shows, the arbor vitae association is the habitat 

 of a large number of species of ferns, which form a prominent part of the 

 flora of the association. Camptosorus was found in four widely-separated 

 situations, growing luxuriantly upon fallen logs. Plants of Pteris more than 

 four feet in height are rather common. Osmunda cinnamomea is common, 

 but only two specimens of O. regalis were seen. Botrychium virginianum 

 is abundant. Prothallia of O. cinnamomea are common. 



A single plant of Lycopodium lucidulum, probably the last representative 

 of its species, was found. The disappearance of this species is indicative 

 of what has occurred in the case of many other northern forms and of the 

 eventual fate of those that remain. Another disappearing species is 



