202 Part III. Chapter 2. 
areas in other parts. of Florida and the adjoining States. There are high river 
bluffs and deep ravines with steep slopes. In these ravines, and especially on 
the north facing slopes, is to be found a mesophytic association of plants that 
is abundant farther north, but which reaches its southern limit here. Amon 
the plants of this association are beech, mapel (Acer floridanum), Mitchella, 
Hepatica, Sanguinarıa, Epigaea, Anemonella (Syndesmon) and many other 
species that dominate in mesophytic northern woods. In this association one 
finds two of our most notable endemic plants-Torreya and Croomia‘). They 
presumably are preserved here perhaps because of exceptionally favorable 
topographic conditions, while in other places which represent their distribution 
in the great Miocene forest they have become extinct because of unfavorable 
conditions. 
Contrast of Mountain and Coastal Floras. The presence of the following 
on the Pocono plateau and the coastal plain is thus accounted for: 
Woodwardia virginica L. Scirpus Torreyi Olney. 
Lygodium palmatum Bernh. Scirpus subterminalis Torr. 
Lycopodium inundatum L. Carex Collinsii Nutt. 
Eleocharis olivacea Torr. Carex albolutescens Schwein 
(C. subulata Michx.). 
Orontium aquaticum L. Polygonum Careyi Olney. 
Eriocaulon septangulare With. Myriophyllum tenellum Bigel. 
Peltandra virginica L. Rhexia virginica L. 
Pontederia cordata L. Proserpinaca palustris L. 
Juncus pelocarpus E. Mey. Limnanthemum lacunosum Vent. 
»  militaris Bigel. Utricularia purpurea Walt. 
Aletris farinosa L. » cornuta Michx. 
Amianthium (Chrosperma) muscae- Habenaria (Blephariglottis) blephari- 
toxicum Walt. glottis Willd. 
Originally developed as mountain or plateau forms, they spread down to 
the coastal plain, where by mutation they were augmented undoubtediy by 
new forms. After the ice sheet had moved off from the Pocono plateau, which 
suffered glaciation many of the old plateau forms returned from glaciated 
mountain crests to reclothe the table land left bare by the retreat of the 
glacial ice‘). On the unglaciated mountain crests south of the terminal moraine 
of New Jersey, which represent a former peneplain, exist plants referred to 
above found in great numbers in sandy soil along the Atlantic coast. Ac- 
cording to N. L. BRITTON the most noteworthy are Juncus Greenii, Solidago 
Puberula, Orontium aquaticum, Tephrosia (Cracca) virginiana, Lespedesa larta, 
ı) Cowıes, H. C.: Colony of northern Plants along the Appalachicola River, Florida. Read 
at Eight International Geographic Congress, Sept. 10. 1904. 
2) HARSHBERGER, J. W.: An ecologie Study of the Flora of mountainons North Carolina. 
Botanical Gazette XXXVI: 247 and 379. 
