19] 
ormations which give it the name of “trap” rock. It is 
rich in minerals and supports a number of plants, such as the 
walking-fern, bladder-nut (Staphylea trifolia), purple clematis 
(Clematis verticillaris), and bluebells (Campanula rotundifolia), 
which are most frequently found on limestone. Neither the sand- 
stone nor the diabase is represented in the Local Flora Section, 
since their characteristic plants are found also on the limestone and 
serpentine outcrops, but enormous boulders of the diabase, trans- 
ported by glacial action, are frequent in the terminal moraine of 
_ Garden. (See Brooklyn Botanic Garden, Guide No. 7, 1932.) 
Mountain area.—North of the Carolinian (coastal-plain) and 
ae Alleghenian zone of deciduous trees is the Canadian forest of 
spruce (Picea) and fir (Abies), yellow and paper birches (Petula 
lutea and . papyrifera), and an undergrowth of small plants or 
little shrubs familiar to all vacationers in northern New England, 
the Catskill Mountains, and the Adirondacks: the bunchberry 
(Cornus canadensis, Fig. 9c), the twin-flower (Linnaca borealis), 
creeping snowberry (Chiogenes), painted trilliium (Vrillinm wn- 
dulatum), the hobble-bush (liburnum alnifolium), and rhodora 
(Rhododendron canadense). These follow, in general, the range 
of the black or bog spruce (Picea mariana), of which the eastern 
distribution is shown in Fig. 4, Map 1; but they do not extend so 
far northward. The black spruce penetrates farther into the arctic 
than any other tree of eastern America. In our area these plants 
are only rarely found below the 1000 ft. level, as shown in Fig. 3A, 
such lowland occurrences being usually in spruce bogs. 
through the red sandstone and frequently show the columnar or 
staircase f 
— 
GUIDE TO THE PLANTINGS OF THE LOCAL FLorA SECTION 
The last trace of original vegetation disappeared from the 
sotanic Garden area long ago, and all plants have been brought in 
from the outside, either by collection, gift, or purchase. Before the 
Brooklyn Botanic Garden was established, in 1910, a border mound 
had been constructed along Flatbush Avenue, and this border 
mound now cuts off much of the noise of traffic and the distracting 
ights of that thoroughfare. The border mound, as well as other 
portions, was heavily planted with privet, weigela, and other Old 
World shrubs and trees, and our reconstruction work has required 
— 
