Northern Piedmont District. 469 
therefore, form a mixed vegetation which covers the ground except where the 
pure association of single species occur and give character to the herbaceous 
flora of such woodland areas. The following species may be included in this 
category. They are arranged in what follows according to the aspects i. e 
according to the months in which they appear in flower. 
Terre Knaur: Asplenium filix foemina. 
Dentaria laciniata, Viola palmata, Ranunculus abortivus, Geranium maculatum, Ari- 
saema Se ‚ Erigeron bellidifolium, Sanguinaria canadensis, Hepatica en Anemonella 
thalietroides, Keil (Panax) trifolia, Mitella diphylla, Viola labradorica (V. canina var. Muhlen- 
iR: V. ER V. villosa, V. e a, Carex pennsylvanica, Barbarea vulgaris, Teen fas- 
eicularis. 
May. ÖOsmorrhiza longistylis, Smilacina racemosa, Viola pube:cens, Aphylion (T une; uni- 
florum, Ol stricta, Oakesia Fee sessilifolia, Trientalis americana, Polygonatum giganteum, 
Medeola virginica, Orchis spectabilis, Hypoxis erecta, Tiarella cordifolia, Hydrastis ae 
Thaspium trifoliatum var. aureum, Aralia nudicaulis, Cypripedium acaule, Allium tricoccum, Ari- 
saema dracontium, Hieracium venosum, Oxalis Yoiee acea, Uvularia perfoliata, Smilax herbacea, 
Geranium maculatum, Luzula campestris, Ranunculus ficaria. 
J Pirola rotundifolia, Galium triflorum, Cynoglossum virginicum, Corallorhiza odontorhiza, 
Uvularia grandiflora, Scutellaria serrata, Liparis Hilifolia, Cypripedium pubescens, Cypripedium parvi- 
rum, Hieracium Gronovii, H. scabrum, Chimaphila maculata, Galium aparine 
July. Cimicifuga racemosa, Laportea canadensis, Chelone glabra, Prnkiaih dichotomum, 
Lilium canadense, Monotropa uniflora, Prunella vulgaris, Silene stellata, Phryma leptostachya. 
ugust. Lobelia syphilitica, Solidago bicolor, Aster Seen Panicum microcarpus. 
September. Aster laevis, Solidago caesia, Collinsonia canadens 
Hemlock Formation. This formation occurs on the sloping hillsides and 
precipitous banks of streams. The forest of hemlock consists in a few places 
of a pure growth without the admixture of any other tree species, but usually 
associated with the hemlock, 7suga canadensis, the botanist finds the beech, 
Fagus americana and red maple, Acer rubrum. These trees are tolerant of 
the dense shade of the hemlocks. Where the forest has not been disturbed, 
sapling hemlocks, beeches and red maples are present ready to replace the 
dominant trees when they have succumbed to the wind. On the floor of the 
forest we find a Lycopodium Association of /./ucidulum; the laurel, Kalımia 
latifolia, occurs in the drier soils and forms a thicket, and the Mitchella- 
Association of M. repens carpets the ground with Viola rotundifolia as a 
character-plant, with which grows Goodyera pubescens, Cinna latifolia, Hie- 
racium paniculatum, and in late summer Aster divaricatus. — In many places, 
the hemlock, forms an element in the mixed deciduous-forest formation. When 
such is the case, it is found in isolated patches usually of a few trees near 
the water-courses on steep hillsides. It forms then an association (Tsuga 
Facies) and with Zycopodium lucidulum are found three other species, viz., 
L. annotinum, L. clavatum, L. dendroideum which grow near the hemlocks 
Two alternative hypotheses may be adduced for this. Either an original hem- 
lock forest has been replaced by a deciduous one, or occasional hemloch 
trees have been under certain edaphic conditions developed amidst the com- 
ponent species of the deciduous forest. 
