74 • HARPER 



moist pine-barrens, are rare here, and adhesive fruits are alto- 

 gether wanting, which would seem to indicate that hairy quad- 

 rupeds do not frequent these swamps. 



The number of species, genera, and families in this list is al- 

 most the same as for the creek-swamps. The largest family is 

 Cyperaceae, with seven species, all of the genus Car ex. The 

 Ericaceae are conspicuous by their absence. Only 23.2% of the 

 angiosperms are monocotyledons. 



Probably every species in this list grows in the upper third of 

 the coastal plain, and many of them extend still farther inland- 

 Several of them are rare — and others absent — in Florida, doubt- 

 less because there is only one muddy river 1 in that state, the 

 Apalachicola. It is noteworthy how many of these plants (some- 

 thing like half of them) extend up the Mississippi valley nearly 

 or quite to the extreme edge of the coastal plain in southern 

 Illinois. This points to an exceptional development of swamp 

 vegetation along and near the Mississippi River. 



These species are all strictly American, and mostly Eastern 

 North American, probably none reaching the Pacific coast, and 

 less than half a dozen reaching the West Indies. 



Remarks on the Eight Preceding Lists. 



The eight habitat-groups thus far discussed (with the possible 

 exception of the rock outcrops) may be considered as forming 

 a linear sequence. There is an almost perfect gradation from 

 rocks through pine-barrens and branch-swamps to muddy river- 

 swamps. This is proved by the fact that as a rule any species 

 which occurs in more than one of these habitat-groups occurs 

 only in consecutive groups. The same is perhaps true to a lesser 

 extent of genera and families. For instance Aster squarrosus 

 grows on rocks and in dry and intermediate pine-barrens; 

 Gaylussacia dumosa'va. dry, intermediate, and moist pine-barrens ; 

 Erigeron vernus in intermediate and moist pine-barrens and 

 branch-swamps; Ludwigia pilosa in moist pine-barrens, branch- 

 swamps, and creek-swamps; and Acer rubrum in branch-swamps 

 and all three classes of river-swamps. It is unusual however to 



1 1, e., one which originates north of the pine-barrens and carries mineral 

 sediment. 



