187 
association with the vegetation of the West Indies. Some plants 
of the Coastal Plain are occasionally found in the interior, as for 
example Helonias bullata (Vig. 11e), at Budd’s Lake in New Jer- 
sey. And some have widespread range to the northward such as 
the ornamental Corema Conradii, which is known in our area only 
from the New Jersey pine barrens, and from exposed quartzite 
ledges on the Shawangunk Mountains of southern New York. 
Hudsonia (Fig. 8d) is distributed in sand dunes about the Great 
Lakes, as well as in our coastal dunes and sand barrens. The num- 
ber of interesting plants found in our area only in the pine barrens 
is large, and only a few can be mentioned. 
3. Limestone —Outcrops of limestone (Fig. 3C) extend from 
the Shenandoah Valley in Virginia into western New Jersey and 
across the Hudson River into western Massachusetts and western 
Connecticut. The friable texture of limestone and its attractive 
weathering make it the ideal stone for rock gardens, and provide a 
foothold for walking-fern (Camptosorus), wall-rue (Asplenium 
Ruta-muraria), and the cliff brakes (Pellaea atropurpurea and P. 
glabella) ; and for many flowering plants such as the sharp-lobed 
hepatica (Hepatica acutiloba, Fig. 13d) and the scarlet fire-pink 
(Silene virginica, Vig. 6a), which barely comes into our area. Rich 
woods and swamps bordering such limestone outcrops frequently 
have an abundance of orchids: the large and small varieties of the 
yellow lady's slipper (Cypripedium pubescens); the showy lady’s 
slipper (Cypripedium hirsutum), the most spectacular of all our 
native plants and still to be found in one or two swamps in western 
New Jersey; and the showy orchid (Orchis spectabilis). And 
scarcely a swamp can be found in this limestone area which does 
not have a supply of fringed gentian (Gentiana crinita) in the fall. 
4+. Serpentine—This is a soft greenish rock containing mag- 
nesium, Several square miles occur on Staten Island (Fig. 3C), 
and a few small lenses to the northeast, but the barrens which ex- 
tend southwest from Philadelphia to the Delaware line are by far 
— 
— 
the best representation in our area. From these barrens have come 
the well-known Phlox subulata (Fig. 6b), now cultivated in a great 
variety of forms; Cerastiuim arvense, especially the large-flowered 
var. villossissimum (Fig. 6c), known only from these barrens; a 
low clematis (C. ochroleuca) ; a small-flowered white aster (4. 
— 
ye 
