424 



BOTANICAL GAZETTE 



[may 



determined mainly by Festuca rubra, Danthonia spicata, Agrostis 

 maritima, and Panicum implicatum in rather open formation. 

 Lecliea intermedia, Vaccinium Vitis-Idaea, Potentilla trident ata, Fra- 

 garia virginiana terra-novae, Juniperus horizontalis , Empetrum ni- 

 grum, Barbula, and a species of moss form more or less extensive 

 mats. Other more scattered species are Campanula rotundifolia, 

 EupJirasia americana (?), Cerastium arvense (?), Solidago hicolor, 

 Plantago maritima, Iris setosa (?), Veronica serpyllifolia, Arenaria 

 lateriflora, Plantago major, and several ruderals. 



Fig. 7. — Picea canadensis showing layering; individual trees plainly seen in 

 center of fig. 5. 



A second and in some places a third series of much lower dunes 

 is met in transect to the west. At the northern end of the complex 

 practically all the white spruce is excessively infected with Ar- 

 ceuthohium pusillum, presenting the most remarkable development 

 of witches' brooms it has ever been my privilege to see. 



We have here a most remarkable physiographic condition of a 

 dune moving seaward. The trees have mostly germinated at a 

 lower level, and as the sand blows over the rounded top of the 

 "grassy foredune" it forms a gentle lee slope to the west among 

 these trees. As the trees are covered, abundant layering takes 

 place, giving a long-lived and self -perpetuating stand (fig. 7) . There 



