272 THE PLANT COVERING OF OCRACOKE ISLAND. 



petraea, Physalis viscosa, Diodia teres, etc., and the difference in soil 

 and light is not sufficiently great to cause any apparent modification 

 in the plants. In larger groves, where the light is more diffused and 

 some humus collects, Oplismeniis setarius ^ covers the ground with its 

 creeping stems, associated with such normally shade-loving species 

 8is Sanicula sp.y Aspleniuni platyneuron {A. ebenoides), Uniola laxa 

 (U. gracilis), Panicinn laxiflorurn and two mosses, growing on the 

 ground, Brymn argenteum and Rhynchostegium serrulatuni. 



THICKET FORMATION. 



Thickets of I/ex vomitoria, by far the most abundant woody plant 

 of Ocracoke Island, often cover the low dunes, especially near the 

 inner side of the island. The plants are here usually 10 to 20 deci- 

 meters high, with short, rigid, thorn-like branches, light-gray bark, 

 thick evergreen leaves and bright scarlet berries. The branches are 

 often shaggy with lichens, notably Ramcdina montagnei. Occasion- 

 ally the Ilex gives place to small, dense thickets of Myrica carolinen- 

 sis, sometimes 4^ meters high. This formation corresponds in a 

 measure to the "Maquis" or "Garrigues" of the western Mediter- 

 ranean region.^ The herbaceous species that have established them- 

 selves among these shrubs are chiefly such as are most abundant on 

 the beach and open dunes. Two thin-leaved, shade-loving herbs are 

 occasional, Fariefaria dehilis with weak, much-branched stems, and 

 Melotliria pendida, with twining stems. 



SALT-MARSH VEGETATION. 

 CREEK-MARSH FORMATION. 



Salt marshes fringe all the small creeks and ditches that intersect 

 the lower part of the island, and sometimes cover broader tracts imme- 

 diately bordering the sound Avith a growth that is almost everywhere 

 dense and reed-like. 'I'wo rather sharply defined belts are distinguish- 

 able along the larger creeks, an outer, covered chiefly with Spartlna 

 stricta, and an inner, where Juncus, roemerianus predominates. The 

 latter alone occupies the small creeks and ditches which are farthest 

 from the beach. 



SPARTINA STRICTA ASSOCIATION. 



The Spartina prefers the edge of open water, where it is in large 

 part submerged at high tide. It has a light, yellow-green color dur- 

 ing the growing season, but is brown and discolored much of the year. 

 The stems are usually about 6 decimeters high. Scdicornia herbacea, 

 often bright red and conspicuous, grows rather abundantly with the 



' In southern Mississippi, also, I found this species growing only in the shade of 

 Qiiercus virginiana. 

 2 Compare Grisebach, Veg, der Erde, vol. 1, pp. 294, 328, etc. 



