: [Vor. 3 
352 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
character of soil and surface rock. The timbered portion 
may be divided into low woods, bluffs, upland woods, and 
copses or thickets. 
The low woods are confined to the alluvial valleys of the 
larger streams. The lower parts are subject to overflow and 
farther back from the streams a second terrace or bottom is 
often found. Characteristic species of the low woods are 
Carya illinoensis, Salix longifolia, S. nigra, Betula nigra, 
Quercus macrocarpa, Benzoin melissaefolium, Platanus occi- 
dentalis, Acer saccharinum, Adelia acuminata, Aristolochia 
tomentosa, Onoclea sensibilis, Cinna arundinacea, Carex trib- 
uloides, C. crus-corvi, C. Grayii, var. hispidula, Commelina 
hirtella, Saururus cernuus, Laportea canadensis, Pilea pu- 
mila, Polygonum virginianum, Iresine paniculata, Iodanthus 
pinnatifidus, Arabis dentata, Ranunculus septentrionalis, Ly- 
copus rubellus, Diapedium brachiatun, Galium V aillantii, Her- 
acleum lanatum, Sicyos angulatus, Lobelia cardinalis, Eupato- 
rium coelestinum, and Aster Tradescanti. Some of these spe- 
cies extend their range through the second bottoms to the 
bases of the bluffs or into low prairies where moisture is 
abundant, and mingled with them are many plants more 
common in the latter situations. 
The alluvial valleys are usually bounded by cliffs, rarely 
more than 50 or 60 feet in height, along the slopes and bases 
of which is found a very characteristic and varied flora, espe- 
cially where the face of the cliff has a north or east expo- 
sure. These bluffs are usually well wooded, affording shade 
and protection for herbaceous species; they are supplied with 
abundant seepage water, have accumulations of soil washed 
from the hills above and are enriched by the leaf mould 
and vegetable humus of ages. On account of their inaccessi- 
bility and little value for utilitarian purposes they have re- 
mained more nearly in a primitive state than any other 
portion of the area. Here are found many plants common to 
the northeastern states, most of the ferns and orchids, and 
some of our most beautiful and delicate wild flowers. The 
list of plants peculiar to this zone is a long one but the fol- 
