302 BOTANICAL GAZETTE [APRIL 
? 
needed in this connection, it seems likely that Vitis is subsequent 
to the dune. 
A little above the center to the left in fig. 76 isa young cedar, 
Juniperus Virginiana. This little plant is several meters up the 
slope and is unquestionably subsequent. In the left foreground 
of fig. ro is a shrub of the chokecherry, Prunus Virginiana, which 
is certainly subsequent to the dune. In fact this shrub is rather 
frequent in such locations. The author does not feel clear as to 
the conditions which permit the germination and development 
of these plants in such unstable situations, for it must be remem- 
bered that the advance is rather rapid in all cases. No seedlings 
of the cherry, grape, or cedar have been seen in any such loca- 
tion. It may be that the germination and early growth took 
place when there was a temporary lull in the advance or during 
extremely moist seasons. The question cannot be fully solved 
without a careful study of marked plants for several seasons. 
So far as the capture of the dune is concerned, it is a matter 
of no moment whether the vegetation is antecedent of subse- 
quent. All contribute together to the common end. Of the 
plants mentioned thus far, Corispermum (shown in the left fone 
ground of fig. 12) is of no value in dune capture, because of 
annualhabit. Prunus Virginiana and Populus monilifera ate pa 
abundant enough on lee slopes to be of much value; especia'y 
because they have little or no vegetative propagation. 
plants which seem to thrive and increase their area wish 
on rapidly advancing lee slopes are Salix adenophylla rie 
phylla, Cornus stolonifera, and Vitis cordifolia. None ot these, a 
ever, flourish except on the protected slopes. They are bese 
to grow along the crest, and hence unable to check the con 
advance of the sand. pidly 
Vegetation seems to be unable, then, to: capture 4 pik 
moving dune. No such dune has been seen where the a 
tion has secured a greater foothold than is represented ! 
zy andz6. This dune isin no sense captured; inde 
ress is scarcely checked. The more vigorous plat ed . 
an uncertain foothold for a long time, and again thee 
ed, its pros" 
ay r etaill 
a els re 
