1899] DUNE FLORAS OF LAKE MICHIGAN 373 
So long as the coniferous forests remain more or less open, 
the three dominant heath plants, Arctostaphylos Uva-urst, Juniperus 
tommums, and J. Sabina procumbens, retain their prominence. Of 
these Arctostaphylos is the most persistent, and may be regarded 
a the most characteristic plant of the forest undergrowth. There 
we occasional shrubs in the open places, such as Shepherdia 
Canadensis, Diervilla trifida, Rosa Engelmann, Prunus pumila. 
Among the herbs in open places are Calamagrostis longifolia, 
Aster laevis, Smilacina stellata, Arabis lyrata, Lithospermum Iurtum. 
Many mosses occur more or less shaded by the evergreens, 
Specially Thuidium and other trailing varieties. ig. 79 shows 
4 coniferous society at the summit of a dune, The trees are 
thite pines; the shrubs in front of them, Jumiperus communis ; 
lose at the left, J. Virginiana. The grass in the foreground is 
Andropogon scoparius. Coniferous forests on exposed slopes are 
shown in figs. 6 and 21. 
The coniferous forests heretofore considered are chiefly on 
‘Xposed slopes and summits. Sometimes there are coniferous 
botests farther inland developed on older and lower dunes. The 
Motection here is greater and the air is less xerophytic. Exten- 
‘We forests of this type were found between Frankfort’ and 
mpité and on Beaver island. The trees are chiefly pines ag 
"ais just as before, but the evergreen undergrowth of ay ey 
F- bearberries is largely replaced by such plants as Vaccinium 
Si A lanicum, V. Canadense, Epigaea repens, Gaulthena sgl 
8, Linnaea borealis, Melampyrum Americanum, Plens agi 
' le 4 the more open and sterile places there is ae re 
“ n carpet, consisting largely of Cladoma rangife pe 
‘ Petia Species) or Polytrichum commune, At the are 
. = of the lake plant societies of this type become engl 
| 2 barrens, On the east coast of Beaver island there a 
| sine fe eration series from the heath on the eee te ; 
ca is est like that described in this paragraph in cagak 
there is almost no undergrowth at all. The se 
the fous or shrub vegetation is due to the dense ree 
Car : ; mit of the 
Pet of pine needles. This last type is the sum 
