* SALT-MARSH VEGETATION. 273 



grass. 1 Distichlis spicata (Z). maritima) usually accompanies this 

 association, but is not of primary importance. 



JUNCUS ROEMERIANUS ASSOCIATION. 



The Juncus roemerianus association occupies much more ground 

 than that of Spartina, and comprises a much larger number of species. 

 It is best developed on land that is merely wet a great part of the time, 

 and covered with, at most, only a few centimeters of water at high 

 tide. The Juncus is of a dark-green color, and usually reaches a 

 height of about 1 meter, making a dense growth of stiff, sharp- 

 pointed stems and leaves. Among the secondary members of this 

 association certain grass-like plants occur locally in some quantity. 

 Notable are Chaetochloa imberbis perennis, with weak, slender culms 

 from short, knotted rootstocks, preferring the borders of the marsh, 

 and Typha latifolia, usually standing in water of some depth. Spar- 

 tina patens (S. juncea) is occasional, the salt-marsh form being smaller 

 and more slender than that which grows upon the sand strand. Pas- 

 palum distichum and Distichlis spicata are also met with in more open 

 places among the Juncus. 



Conipositae, with mostly rather succulent leaves, are conspicuous, 

 especially near the margin of this association. Aster tenuifolius, a 

 slender rush-like perennial species whose few branches terminate in 

 solitary, rather large heads with showy white rays, is less abundant 

 than the related Aster subulatus, a much-branched, often rather stout 

 annual with numerous inconspicuous heads. Solidago sempervirens 

 and Baccharis halimifoliaura most at home on the edge of the Juncus 

 growth. Both are showy plants, the latter with bright white pappus, 

 the former with a golden-yellow panicle. Borrichia frutescens, one of 

 the most characteristic plants of the strand, prefers comparatively 

 open spots where the ground is merely wet. It has a stout stem, 

 usually 3 to G decimeters high, thick whitish leaves, and yellow sun- 

 flower-like heads. Iva frutescens is the most abundant composite of 

 the marshes, almost always associating with the Juncus. Two climb- 

 ing plants, Galactia volubilis {Q-. pilosa) and Vincetoxicum palustre, 

 a glabrous, narrow-leaved asclepiad, occur near the edges of the marsh, 

 twining around the stems of the rushes and other plants. Atriplex 

 hastata is occasional in similar situations. Even Ilex vomitoria some- 

 times strays into the marsh, growing among the Juncus as a low 

 straggling shrub. 



Somewhat different is the assemblage of species about the small 

 pools that frequently interrupt the growth of Juncus roemerianus. 



1 Likewise in southwestern France, Spartina stricta and Salicornia herbacea 

 form the outermost association in soil that is submerged at high tide. (Conte- 

 jean, Geogr. Eot. , p. 56.) According to Warming (Lehrbuch, p. 307) Salicornia 

 herbacea grows unmixed with other species as the outermost embryophylic vegeta- 

 tion on the eastern shores of the North Sea. Spartina stricta does not range so 

 far north in Europe. 

 2<m 2 



