MARYLAND WEATHER SERVICE 17!) 



the role of a pioneer as do the species of Spartina, it persists after 

 the marsh has become somewhat drier, hence forming wide areas 

 toward the land side of a marsh. It is more apt to grow in mixed 

 association than are the species of Spartina, and may be accompanied 

 by Scirpus robustus, Cyperus strigosus, Acnida cannabina, Atriplex 

 hastata, Lythrum lineare, Solidago sempervirens and Plucliea cam- 

 phorata. The last named plant imparts a purple hue to this asso- 

 ciation in late summer. 



Distichlis association. — As sediment and vegetable matter accumu- 

 late, the level of the marsh rises, and the species of Spartina either 

 do not find a suitable footing, or are crowded outward (i. e. toward 

 the stream) by other grasses, chief among which is Distichlis spi- 

 cata. This is a much finer textured grass and has a lower habit 

 of growth. It grows in close mats, sometimes to the exclusion of 

 other plants, as at the mouth of Parkers Creek, Calvert County, 

 where Distichlis with a little Spartina patens occupies the fore- 

 ground, while Spartina stricta occupies a deeper region farther back. 

 Owing to the more mesophytic positions in which the Distichlis 

 grows, it is generally accompanied by a variety of dicotyledonous 

 plants such as Lythrum lineare, Ptilimnium capillaceum, Poly- 

 gonum sagittatum, Sabbatia stellaris, Gerardia maritima, Solidago 

 sempervirens, Pluchea camphorata, Aster tenuifolius. Hence it is 

 apt to present a brighter and less monotonous appearance than the 

 associations already described. This may be seen on Chaptico 

 Creek, St. Mary's County. 



Iva-Baccharis-Panicum association. — The two shrubby Compositae 

 Iva frutescens and Baccharis halimifolia with much Panicum vir- 

 gatum and a variety of other plants frequently occupy a higher 

 and drier position than the preceding, on the landward margin of 

 a marsh. Iva can apparently endure a moderately high proportion 

 of salt, for it sometimes occurs as scattered individuals in the other 

 associations, quite near the water, while Baccharis may persist after 

 the tract has become dry and meadow-like. In the more open parts 

 of this association may be found Sabbatia stellaris, Pluchea cam- 

 phorata, Strophostyles umbellata, Gerardia purpurea, while Wil- 

 lughbaea scandens clambers over the shrubs and adorns them with 



