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which bear the leaves. The leaves of the season are more or less 

 coated with a bloom which gives them a somewhat whitish ap- 

 pearance. The tips of the runners project into the air at an angle of 

 about 25° to 30°. Should blowing sand encounter them a small ridge 

 is built. Between these runners debris accumulates fairly rapidly, and 

 as it is not blown away during the winter it contributes to the en- 

 richment of the soil. Many seeds also are retained, and when proper 

 conditions are attained they grow. Some of them may replace the 

 heath altogether. This juniper, as well as the other two heath plants, 

 has seeds which are eaten by birds, although the birds seem to prefer 

 the bright red berries of Arctoskiphylos. The latter plant, known as 

 the bearberry, is of second importance. What has been said about 

 Juniperns hori::ontalis applies here almost equally well. The develop- 

 ment of the runners is not so noticeable, however, and a greater 

 amount of debris is retained in its denser network of branches. 



The development of Juniperus communis depressa reminds one very 

 strongly of the development of conifers near the tree line in Lapland 

 (Kihlman, 1890). The truncated top of this plant is characteristic 

 of all the individuals wherever they are growing. Some of these ta- 

 bles are a little over a meter in diameter. They vary in hight from 

 about two decimeters up to nearly a meter. The explanation which 

 Kihlman found to solve the problem in Lapland has no bearing in 

 this case, however, for it seldom happens that there is sufficient snow 

 in winter to cover even the lowest of these tables. The explanation 

 lies more probably in the fact that this growth is a germ character of 

 the species, for, in so far as evidence is at hand, edaphic factors 

 merely change the amount of growth and not its manner. 



For northern Michigan, where the heath is much better repre- 

 sented than in this region, Whitford (1901:298) lists the character 

 plants as follows: Juniperus communis, J. horizontalis, Arctostaph- 

 ylos uva-ursi, bracken (Pteris aquilina), Zygadenus chloranthus, 

 Solidago nemoralis, bluebell {Campamda rotundifolia), and Couian- 

 dra nmhellata. Of the eight species, five occur in the Beach area, and 

 four of these are important members of the heath association. 



Secondary species in this association are not very numerous and 

 very few of them are typical of the association. They are either rel- 

 ics of past associations or invaders of succeeding ones. In no case do 

 they add to the general character of the vegetation, although they 

 may greatly change the appearance of individual parts. 



The health plants come in on Calamovilfa or Prunus puniila dunes, 

 which they work over into Juniperus dunes. In the meantime the 

 plants spread from the dune over the interdunal spaces. When these 



