360 BOTANICAL GAZETTE [ NOVEMBER 
much salt but little immersion, are amply explained by the 
adaptations of the members above described, notably their annual 
character and excellent mode of dissemination, their xerophytic 
structure, and the power of salt resistance possessed by their 
roots (at least in the two dominant members). 
The members of the association grow often fairly intermingled, 
but elsewhere one or the other form may predominate, even for a 
considerable area, to the exclusion of the others. This irregular- 
ity of commingling is probably due to the fact that, all of them 
being annuals, the precise place of their occurrence in any given 
year is largely a matter of accident, due to the way the seed dis- 
tributing agencies of wind and water happened to drift them the 
preceding year. Another irregularity comes from the general 
tendency for the Salicornia to be nearest the water, the Suaeda 
next, the Spergularia and Atriplex last, a distribution amply 
explained by the comparative degrees of xerophilism and air- 
storing capacity of the members, as above described. 
Since the members are all annuals, all of nearly the same size, 
and all grow in an open order interfering little with one another, 
it is possible that this association is simply a mixture of forms 
which happen to be adapted to a similar habitat, with no ecolo- 
gical bond, but only coincident interests, between the members. 
Indeed, in the present state of knowledge, it is impossible to say 
that this is not the case with the members of all associations, 
though I think not, as will later be discussed. 
Although thus very prompt to take possession of new marsh, 
this association can hold its ground only temporarily, for the 
slow-moving Spartinetum advances upon it from below, and the 
Staticetum upon it from above, until between the two it vanishes, 
and disappears as an association from old marsh, existing only 
as scattered individuals, visitors, among the other associations. 
It represents a sort of annual light infantry quick to occupy new 
territory, but easily displaced by the resistless advance of the 
heavy phalanxes of the perennial associations. 
The readiness with which this association takes possession of 
new marsh makes it the first to appear on the new surface pro- 
duced by artificial flooding. When the tide is shut out all the 
