456 Part IV. Chapter 2. 
occidentalis, Negundo aceroides, Acer rubrum of enormous size. Gleditschia 
triacanthos, Quercus aquatica, O. falcata, O. rubra are equally common '). Dense 
growfhs of cane, Arundinaria tecta (Arundinaria Association) forms in 
many places a large part of the ground cover under the large trees. 
In central Arkansas along the Arkansas River and its tributaries this plant 
formation exists in narrow belts on either side of the creeks and larger streams. 
At any con:iderable rise of the streams they are flooded and during the rainy 
season (in late winter and spring), they often remain under several feet of 
water for weeks at a time. Liguidambar and Nyssa sylvatica form here about 
a fourth of the total stand. 
West of the Mississippi River south of the Arkansas River the trees of this 
forest are Ulmus crassifolia, Fraxinus americana; Quercus Michauxii and ob- 
Zusifolia forms the post oak associations which extends westward into Texas. 
This oak is associated on the drier less sour soils with Quercus alba, Q. falcata, Celtis mis- 
sissippiensis, while the umlergroweli consists of Bumelia een eg virginiana, Crataegus 
viridis, Planera aquatica, Cornus strieta, C. sericea, Ilex d Lianes are frequent comprising 
Vitis PORNBEHSOEIR, V. aestivalis, Ampelopsis cordata, A. Aa pP. rianetelle Clematis virginiana, 
& and several species of Smilax. Sabal seen grows everywhere in the higher drier 
ground that border the morasses and swamps. The wet soil of these woods supports Carex erus- 
corvi, C. stipata var. maxima, C. decomposita, C. Freie C. Torreyi, Muhlenbergia mexicana, 
M. diffusa 
The herbaceous plants of these hardwood bottoms are Dioclea Boykinii, Amorpha fruticosa, 
Aster diffusus, Solidago (several species), Dianthera humilis, Hygrophila lacustris, Trepocarpus 
aethusae, Cynoscyadium digitata, Asclepias perennis, Feen difforme, Gratiola virginiana. 
Perhaps the most remarkable aggregation of trees in the north temperate 
zone is found in the lower Wabash Valley in Illinois where the number of 
indigenous species south of the mouth of White River is one hundred and 
seven. Our knowledge of this forest is due to two men Dr. ROBERT RIDGWAY 
and Dr. JACOB SCHNECK ’). 
The forests of this territory are emphatically of the mixed type as it is 
rare to find a single species predominating over the others though in particular 
localities Quercus alba, Acer saccharum, Liguidambar styraciflua may largely 
prevail. Usually however the 107 species of trees are mixed together indis- 
criminately the relative abundance of the component species varying with the 
location, character of soil, geologic formation and other local causes. An area 
of less than one square mile showed the following seventy five species of trees: 
Asimina triloba L. Acer dasycarpum Ehrh. (= A. saccha- 
Acer saccharum Marsh. (= A. saccha- rinum L.). 
» rubrum L. [rinum Wang.). | Gleditschia triacanthos L. 
I) SARGENT, CHARLES $.: Report on the Forests of North America. ıoth Census 1884: 535: 
2) Rınawav, ROBERT: Notes on the native Trees of the lower Wabash and White River 
Valleys in Illinois and Indiana. Proceedings U. S. National Museum 1882: 4988; Notes on the 
The Forests of the Wabash Valley. Garden and Forest VIII (1895): 101; SCHNECK, J.: C 
of the Flora of the Wabash Valley. Cox’s Geological Survey of Illinois 1875: 504—579- 
