298 



white flowers considerably lighten the general dull gray tone of the 

 dead leaves of the Andropogon. This is the vernal aspect. Next to 

 secure color prominence is Lifliospeninuii giucUni, which blooms dur- 

 ing June and July. This plant is not actually abundant in the typical 

 part of the association, but its manner of growing and the abundance 

 of its brilliant orange flowers are easily misleading in determining 

 the importance of the species in the association. It is most abundant 

 near the tension line, towards the outside of the association. Al- 

 though this plant has neither dune- forming nor dune-fixing abilities, 

 it seems most at home where this association is invading the lower 

 parts of the dune-complex near Beach. There it occurs at frequent 

 intervals, without apparent discrimination between the lower places 

 and the sides of the dunes. Occasionally it is present on the tops of 

 some of the smaller dunes. Seedlings of this species can be found in 

 various situations, although they are most frequent in depressions. 

 The root system of Lithospeniium gmclini can withstand a moderate 

 amount of either burying or uncovering, so that the plant can easily 

 tenant the dune-complexes of the region which are protected from 

 the westerly winds by the area of the pines. It seems to fulfill the 

 position of pioneer to the Andropogon scoparius consocies of the 

 bunch-grass association. Cycloloma atriplicij olium , Petalosteinum 

 piirpnreum f. arenarium, and Arcnaria sfricta play the same role, but 

 to a less marked degree. 



The estival aspect of this consocies is characterized by the bloom- 

 ing of the Andropogon scoparius itself, and of the interstitial Pctalos- 

 temiwi piirpnreum f. arenarium (sand-prairie clover). The latter 

 species, which is typically a prairie plant, exhibits marked xerophytic 

 adaptations in several particulars — so much so that a detailed de- 

 scription is necessary, and it is here given in the form of a table.* 



PETALOSTEMUM PURPUREUM f. arenarium FORMA NOVA. 



*This table is taken from the original description of this new form, m 

 Torreya, 11:125-128, June, 1911. 



