I9I0.] ON THE DISTRIBUTION OF PLANTS. 487 



Solidago sctnpervircns 1.00220- 



Siiaeda maritima 1.00220- 



Typlia angustifolia i. 001 60-1. 001 10 



Panicurn virgatiim 1.00140- 



Scirpiis laciistris 1.00140-1.00050 



Scirpus fluz'iafilis i.ooi 10- 



Zizania aquatica i. 001 lo-i. 00000 



All of the plants above the line are able to withstand a maximum 

 of over I per cent, of sodium chloride in the salt water, and may be 

 reckoned as the true salt marsh species, while J'allisneria spiralis, 

 Hibiscus moscheittos, Phragmites communis, and Peltandra virginica 

 are excluded, because their habitat is frequently an inland, not a 

 salt marsh one. All below the line, according to the accurate data 

 presented for the first time, are not able to grow in salt water the 

 sodium chloride content of which approximates i per cent.'' 



By this arrangement we are able to segregate the plants found on 

 the Xew Jersey salt marshes, for although apparently occupying the 

 same geographic position and growing under similar conditions of 

 environment, yet we can divide them into salt marsh species, those 

 that are adapted to a saline soil with from 1-4 per cent, of sodium 

 chloride, and those less well adapted to a saline soil, but which are 

 to be classed among the plants found in fresh-water swamps. Oc- 

 casionally, as the list shows, we will meet with such non-saline plants 

 in a typic saline environment. This is to be explained as in the cases 

 of Vallisneria spiralis, Hibiscus moscheutos, Phragmites com- 

 munis, and Peltandra virginica by their adaptation to more saline 

 conditions. Again there are fresh-water marsh species found on 

 salt marshes, but their presence is to be explained by the fact 

 revealed by the hydrometer, that while the surface marsh soil 

 may be strongly saline, the subsoil is controlled by fresh water 

 which flows outward from the higher ground under the salt marsh 

 sod. Into the subsoil controlled by fresh water the roots of a num- 

 ber of plants of fresh-water habitat grow, notwithstanding the fact 

 that they are growing in the middle of a salt marsh. Appearances 

 here are deceptive and the peculiar behavior of these plants per- 

 plexed me until the hydrometer showed the reason for the presence 



^ See preceding table of percentages and specific gravities with which the 

 above figure may be compared. 



