484 BOTANIGAL GAZETTE [JUNE 
pubescens, Cenchrus carolinianus, Sporobolus cryptandrus, and 
Bouteloua hirsuta, with less of Paspalum setaceum and Andropogon 
scoparius. The secondary species are not numerous, but a few 
species are so conspicuous at certain seasons of the year that they 
make distinct aspects. The Oenothera rhombipetala aspect domi- 
nated during the period in which this experiment was conducted. 
The most important secondary species are Opuntia Rafinesquit, 
Lepidium virginicum, Ambrosia psilostachya, Tephrosia virginiana, 
Chrysopsis villosa, Monarda punctata, Croton glandulosus, Oenothera 
rhombipetala, Cyperus Schweinitzii, Tradescantia reflexa, Specularia 
perfoliata, Lithospermum Gmelini, Petalostemum purpureum, Draba 
caroliniana, Euphorbia Geyeri, Lespedeza capitata, Krigia caro- 
liniana, Cassia Chamaecrista, Pentstemon hirsutus, Antennaria sp., 
and Aster sericeus. The atmometers in these two consocies were 
about 15 m. apart. 
The blowouts.—The blowouts are excavations in the mobile sand 
caused by the action of wind. In this region nearly all of them are 
surrounded by the bunch-grass prairie. The sand is virtually free 
from vegetation except for a few species, such as Acerates viridiflora, 
var. lanceolata, Cristatella Jamesti, and Aristida tuberculosa, which 
find here their preferred habitat. ‘The dry surface layers of the 
sand are blown by every wind, and become very hot on sunny days. 
One atmometer was placed in the bottom of the complex known 
as the Devil’s Hole, 3 km. east of Havana, and another half-way up 
its lee slope toward the east (fig. 3). 
The Quercus velutina association.—The first forest association 
to appear on the sand in this region is characterized by Quercus 
velutina and Q. marilandica. Of the two, the former is usually 
more abundant and better developed. In typical situations 
other species of trees are seldom present. In general, Q. marilandica 
tends to occupy the poorer soil, and is more frequently the first to 
appear on cleared or lumbered land, but Q. velutina seems to be 
more persistent and better able to hold its own. The presence of 
trees of Carya cordiformis may indicate an incipient succession of 
the mixed forest association. Actual count of the trees in the vicin- 
ity of one atmometer showed that 57 per cent of the old trees were 
Q. velutina, 42 per cent Q. marilandica, and 1 per cent Carya 
