19- EAST FLORIDA FLATWOODS. 335 



ground parts too. (The percentage of annuals has not been estimated, but it 

 must be very small). Few if any of the species are confined to Florida. 



Comparing the two columns of percentages in the plant list brings out some 

 very interesting and significant facts. It is evident that Qtiercus falcata, Q. 

 laurifolia, Cornus florida, Ostrya, Betula, Ilex opaca, Sniilax laurifolia, Vitis 

 rotundifolia, Smilax Walteri, and many shrubs and herbs are more abundant 

 west of Trail Ridge than east thereof, while the reverse is true of many other 

 species. (It would take up entirely too much space to repeat their names here, 

 but they can easily be picked out from the Hst by any one who is sufficiently 

 interested). The first category includes the most shrubs, especially Ericaceous 

 shrubs, while the second includes about twice as many trees, small trees and 

 herbs as the first. If we could explain the reason for all these differences in 

 vegetation it would be an important contribution to ecological science; but the 

 problem is by no means a simple one. For the differences between the two 

 halves of the region, although mostly small in amount, are of course of every 

 conceivable kind; and any one of them might prove to be the key in some par- 

 ticular case. Just a few suggestions toward solving the problem will be given 

 here. 



From what is known of their distribution elsewhere it appears that some 

 of the species which are more abundant in the western division prefer somewhat 

 clayey soils, some acid (or non-calcareous) soils, and a few are weeds which 

 have come in with the farmers; but this leaves the majority of cases still un- 

 accounted for. Many of the species more abundant eastward are partial to the 

 low hammocks or marly spots, which are scarcely represented west of Trail 

 Ridge (or even west of the smaller ridge 15 miles east of it). The greater 

 abundance of Liquidambar (sweet gum), Quercus cinerea (turkey oak), and Q. 

 Virginiana (live oak) eastward may possibly be correlated with phosphorus in 

 the soil, for these species have been observed elsewhere to thrive in decidedly 

 phosphatic soils, and phosphorus is generally more abundant coastward. Still 

 others are confined to the sterile sands or old dunes a few miles back from the 

 coast, while a few grow in or near marshes and perhaps belong more properly 

 to the next region. 



The percentage of evergreens is about 74.7 west of the ridge and 73.9 east; 

 of Ericaceae among the shrubs 19 west and 7 east; and of Leguminosae among 

 the herbs 1.7 west and 4.4 east. If we had several chemical analyses of typical 

 soils from both halves of the region we would be in a better position to interpret 

 these figures; but a few suggestions can be made even with our present inade- 

 quate information. 



The evergreen percentages, which are both above the average for northern 

 Florida, ought to indicate soils rather low in potassium, notwithstanding the 

 chemical analysis given a few pages back (which must be abnormal in that re- 

 spect). One of the figures for Ericaceae is above the average and the other 

 below ; and the fact that the first is nearly three times as great as the second is 

 probably correlated with the fact that the western division is essantially non- 

 calcareous, while the eastern has mari near the surface in many places. For 

 the distribution of Ericaceae (particularly those that are not evergreen) seems 

 to be governed by lime more than by potash, as already intimated under the 



