555 
arundinacea. These last two species may occur as local dominants be- 
tween Scirpus fluviatilis and Spartina Michauxiana, and they may have 
been prominent in this position on the original prairies. 
The Spartina Michauxiana Association—Spartina Michauxiana, 
Elymus virginicus, Phalaris arundinacea, Leersia oryzoides, Glyceria 
nervata, Carex vulpinoidea, C. Bebbii, C. scoparia, C. lanuginosa, C. 
tribuloides, Eleocharis palustris, E. obtusa, E. intermedia, Juncus 
nodosus, J. Torreyi, J. tenuis, Cyperus strigosus, Stachys palustris, 
Lythrum alatum, Vernoma fasciculata, V. altissima, Steironema lanceola- 
tum, Lycopus americanus, Aster paniculatus, Asclepias incarnata, A pocy- 
num cannabinum var. hypericifolium, Hypericum ellipticum, Iris versi- 
color, Lippia lanceolata, Senecio aureus, and S. Balsamutae. 
Forest invasion may occur in this association by the species noted 
aboye and also by Populus deltoides, less frequently by P. grandidentata 
or P. tremuloides, and Cornus Amomum. 
The Calamagrostis canadensis Association—Calamagrostis inex- 
pansa, Aspidium Thelypteris, and Onoclea sensibiis were found to be 
more abundant in this association than elsewhere, but the remaining 
secondary species consist largely of an overlapping of the secondary 
species of the Spartina and Panicum associations. This condition agrees 
well with the fact that the Calamagrostis association is sometimes 
eliminated in the succession from Spartina to Panicum virgatum. 
The Panicum virgatum Association—Panicum virgatum, P. Lind- 
heimeri, P. huachucae, P. tennesseense, Elymus virginicus, E. canadensis, 
Ranunculus fascicularis, R. septentrionalis, Baptisia leucantha, Anemone 
canadensis, Oxalis corniculata, Cicuta maculata, Steironema ciliatum, 
Physostegia virginiana, Veronica virginica, Liatris spicata, Solidago ser- 
otina, S. Riddellii, Cacalia tuberosa, Lathyrus palustris, Rudbeckia hirta, 
Stachys palustris, and Gaura biennis. 
Forest invasion in this association on the flood-plain at Savanna was 
found occurring by three different methods: (1) by tree seedlings along 
the forest borders in the shade of overhanging branches which had elimi- 
nated the Panicum, (2) encroachment of Cornus and Crataegus by means 
of adventitious buds from the roots extending into the prairie, and (3) by 
scattered seedlings of Fraxinus americana, Ulmus americana, U. fulva, 
and Populus deltoides on the prairie. A recent fire in a small section of 
this prairie had destroyed most of the seedlings less than six feet in 
height. 
The Andropogon furcatus Association—Andropogon furcatus, Sor- 
ghastrum nutans, Panicum implicatum, P. praecocius, P. Scribnerianum, 
Sisyrinchium angustifolium, Comandra umbellata, Fragaria virginiana, 
Baptisia leucantha, Crotalaria sagittalis, Petalostemum purpureum, P. 
candidum, Desmodium illinoense, D. sessilifolium, Lespedeza capitata, 
Oxalis corniculata, Polygala sanguinea, P. verticillata, Euphorbia Preslii, 
