231 



Nyssa Ogeche, Acer saccharimtm, Arundinaria macrosperma, 

 Wistaria, and Brunnichia probably extend farther south on this 

 river than in any other part of their ranges; and several of these 

 are not known on any other stream in Florida.* 



Now for the interpretation of some of the returns shown in 

 the table. On comparing the two lists it will be seen that herbs 

 and evergreen trees (particularly Sahal Palmetto and Magnolia 

 glaiica) are more abundant in the lower portions of the river, and 

 species of woody plants more numerous farther up, all of which 

 seems to indicate that the vegetation near the mouth of the river 

 is farther removed from the climax condition than that higher up. 

 (Such statistics would not carry much weight if based on this one 

 day's work alone, but I have observed similar relations on several 

 other rivers.) Looking at the matter mgre closely from a floristic 

 standpoint, Fraxinus profunda, Alnus, Scirpus, Cladium, and 

 Phragmites were not seen at all after passing Owl Creek, and 

 Taxodium, Sahal Palmetto, Nyssa uniflora, and Magnolia glauca 

 were noticeably more abundant below there than above. On the 

 other hand, Platanus, Quercus nigra, Populus heterophylla, Ulmus 

 americana, Gleditschia, Hicoria aquatica, Quercus Michauxii^ 

 Carpinus, Acer saccharimtm, Arundinaria, Vitis, Wistaria,. 

 Ampelopsis, BrunnicJiia, and Itea were not identified below OwL 

 Creek, and Salix nigra, Planera, Betula, Liquidambar, Populus 

 deltoides, Fraxinus carolhiiana, Sahal glahra, and Phoradendron 

 were seen considerably oftener in the second part of the journey 

 than in the first, although the first was a little longer. 



The explanation of all these differences between the vegetation 

 near the mouth of the river and that a little farther up must be 

 sought in one or more environmental or historical factors. The 

 environmental difTerences between the two portions are of several 

 kinds, among which may be enumerated the following: — 



I. The upper reaches of the river, being farther north, pre- 

 sumably have a slightly cooler climate. But in such a short 

 distance climatic difTerences due to latitude would hardly be 



* Salix nigra, Acer saccharinum, both species of Populus, Nyssa uniflora, Quercus 

 lyrala, Betula, and Planera are not mentioned in the most complete Hst of Florida 

 plants extant, namely, that of Prof. A. S. Hitchcock in Trans. Kan. Acad. Sci. 

 i6: 108-157. 1899; 17: 79-105. 1901. 



