Gulf Pine Barren-Strand District. 443 
 ded by Tarodium imbricarium. The aquatic vegetation of these consists of 
Cabomba, Brasenia, Nelumbo, Nymphaea odorata, Nuphar advena which asso- 
ciated with Zimnanthemum aquaticum cover the surface of the water very 
densely ’’). 
ie A: in the Altamaha Grit Region are characterized by a rather dense zZ of 
p cypress, Taxodium imbricarium, associated with Pinus caribaea, Nys i ‚ Dex 
mr, ee cordata, Ludwigia pilosa, Saururus cernuus, Lobelia Boykiai, een 
tinata, P. palustris, Sphagnum macrophyllum ete. Perennial herbs are here much more abun- 
Aa than woody plants and the cypress exceeds all other vegetation combined. er pilosa 
often has spongy tissue several times as thick as the rest of the stem. The number of flowers 
is greatest in midsummer. In the shallower pine barren ponds, while not de distinet 
from the cypress ponds, the number of cypress trees is very materially reduced until in some 
YP po 
places this tree entirely disappears. 
Originally many of the rivers in Florida were characterized .by floating 
masses of Pistia stratiotes, but recently the original aquatic vegetation of some 
of the principal rivers notably the St. Johns and tributaries has been almost 
exterminated by the appearance and spread of the water hyacinth Zichhornia 
crassipes (= E. speciosa), a plant introduced about 1890 at Edgewater about 
four miles above Palatka. This plant has spread so rapidly and grows in such 
dense masses, as seriously to impede the navigation of those streams where it 
is found’). 
C. Gulf Pine Barren-Strand District. 
This district includes the coastal plain from the lower course of the 
Suwannee River west and southwest to the subtropic littoral of the Texan 
coast. It merges imperceptibly into the Atlantic coast district on the one 
hand and into the subtropic Tamaulipas region in Texas and northeastern 
Mexico on the other. It is considered as distinct from either of these districts 
for purposes of convenience, and also, because there are quite a number of 
plants peculiar to the Gulf coastal plain, or which reach their most pronounced 
development or most extensive range in this portion of the continent. 
No observations are at hand concerned with the plankton and the marine 
algal associations of the Gulf coast. The strand flora, however, is compara- 
tively well known from the researches of Charles ‘Mohr °) R. S. CocKks and 
those of Francis E. Lloyd and S. M. Tracy). 
ı) Harper, RoLanp M.: Botanical Explorations in Georgia during the Summer of 1901. 
Bulletin Torrey Botanical Club 1903 XXX 
2) WERBER, HERBERT J.: The water Hyaeinth and its Relation to Navigation in Florida. 
Division Botany U. S. Department Agriculture Bulletin 18. 1897. 
3 ‚ CHArLes: Plant Life of Alabama. Contributions from U. $. National Herbarium 
V1: 139, 
cs, R. $.: The Flora of the gulf biologie Station. Bulletin 7 issued by the La. 
State Board of Agriculture and un 1907 with a short history of botany in Louisiana and 
the only complete list of La.-plan vo, Fraxcıs, E. and Tracy, S.M.: The insular Flora 
of Mississippi and Louisiana. a ya Botanical Club XXVIH: Eimseh: March 1901. 
