Carolinian Pine Barren-Strand District. / 427 
B. Carolinian Pine Barren-Strand District. 
This district includes the coastal plain east of the “fall line” between 
Chesapeake Bay and south central Florida. Its physical characters are similar 
to those of the plain in New Jersey, but more pronounced, because in the 
south the plain is wider and better developed. Floristically the district is 
richer than that north of the Chesapeake and there are many plants, such as 
Unzola paniculata, Borrichia frutescens (peculiar to it) to be mentioned sub-se- 
quently which do not extend northward. 
he Lafayette and Columbia geologic formations cover almost the entire 
surface of the coastal plain in Georgia. R. M. HARPER in a detailed account 
of this region distinguishes in addition to the Lafayette and Columbia for- 
mations the fall-line sand hills, the Altamaha Grit region and the southern 
lime-sink region, while the Cretaceous, eocene and oligocene geologic regions 
are also noteworthy. These formations may be identified by the plants growing 
upon them. Certain species of herbaceous plants occur only on the Columbia 
sands others only on the Lafayette clays’). The best indicator of the Co- 
lumbia formation is Zriogonum tomentosum which flowers in late summer 
ranging from South Carolina to Florida and Alabama. Froelichia floridana 
has a similar distribution. 
Baldwinia angustifolium, Asclepias humistrata, Baptisia perfoliata, Chrysobalanus oblongifolius, 
Calamintha Arche Croton argyranthemum, Dicerandra linearifolia, D. odoratissima, Petalostemon 
corymbosum, Nolina iin Paronychia herniarioides, Sarracenia flava, Serenoa serrulata are also 
Ekractenistie, — The Lafayette formation is easily distinguished by Berlandiera tomentosa, Crataegus 
aestivalis, Dichromena ui There are, however, quite a number of species in the coastal 
plain which seems never to occur where the Lafayette is Zeiss. but only on the Columbia or 
on outerops of the older anlerying strata. Among these are Bumelia lanuginosa, Dichromena 
leucocephala, Erythrina herbacea, Hydrangea quereifolia, alaiberi hastata, Taxodium distichum 
and Yeatesia (Justicia) laetevirens. Lastly Tiedemannia teretifolia and Taxodium imbricarium seem to 
indicate the simultaneous occurrence of both the Lafayette and the Columbia geologie formations. 
ı. Sea Coast- and Dune Formations. 
Marine Algal Formation. The nature of the bottom of the ocean and 
sounds along the southern coast of the United States is such as to provide 
few habitats ofthe sort most frequented by marine algae. There are no rocks 
whatever, except those artificially deposited for wharves and revetments. Rock 
pebbles are also wanting. It is not surprising, therefore, to find that the ma- 
rine algae are such forms which attach themselves to shells lying on the 
ı) The most detailed account of the physiography and sbils of the coastal plain with the 
best agricultural map ever published of the distriet will be found in a report by EUGENE A. 
HiLGARD entitled, “Report on cotton Production in the United States also embra acing agricultural 
and p See Descriptions of the several cotton States”. Tenth Census of the United States, 
volumes V a 1834. This is indispensable in a study of the flora 2 the Southern states 
in connection a the chapters in Hilgard's book on “Soils” concerned with the recognition 
of soils from their native vegetation, pages 487—549; Consult also MILToN WHITNEY, Soils of 
the United States. Bulletin 55 U. S. Bureau of Soils, 1909 with excellent colored map. 
