540 
If the soil is sandy, Aster tanacetifolius and Gaillardia pulchella are 
common. 
The Grindelia is considered by many to be a variety of G. squarrosa. 
As seen in the field it certainly seems a good species. It is a simple- 
stemmed annual, often 4 feet or more high, with larger, spinulose- 
margined leaves and larger heads of flowers which bloom earlier than 
G. squarrosa. 
On the upland there are numerous depressions known as “buffalo 
wallows.” These vary from a few feet in diameter to many acres in 
extent. They retain water some time after a rain and are therefore 
likely to present an interesting flora. Of Mr. Thompson’s collection 
the following oecur in such localities: 
Lippia cuneifolia, 
Megapterium canescens. 
Panicum crus-galli. 
The Panicum is erect, a foot or two high, with a contracted inflor- 
escence resembling that of P. colonum, and with scarcely awned flowers. 
Where the soil becomes salty or alkaline one finds Agropyron repens 
glaucum, Atriplex expansa, and Distichlis spicata. The Atriplex is a 
common weed in the Arkansas Valley. 
The stony hills occurring along the streams furnish a characteristic 
flora. Here are found— 
Aster ericwfotius. 
Atriples canescens. 
Bouteloua hirsuta, 
Casalpinia jamesii. 
Crassina grandiflora. 
Hriogonum lachnogynum. 
Euphorbia fendleri, 
Euphorbia lata. 
Euphorbia petaloidea. 
Galpinsia hartwegii. 
Melampodium cinereum, 
Mentzelia decapetala. 
Paronychia jamesii, 
Parosela enneandra. 
Ptilepida acaulis, 
Ptilepida scaposa. 
Rhus trilobata, 
Yucca glauca. 
The Mentzelia is a particularly gorgeous plant. Its numerous yellow- 
ish-white flowers, 3 or 4 inches in diameter, open toward evening. I 
observed the flowers of Galpinsia to be visited at dusk by a sphinx 
moth (apparently Detlephila lineata). 
Along the Arkansas River, on the south side, lies an extensive range 
of sand hills. A similar tract is found along the Cimarron River. These 
regions yield a greater variety of interesting plants than any of the 
others. Mr. Thompson’s collection shows the following: 
Abronia fragrans. 
Asclepias arenaria. 
Calamovilfa longifolia. 
Cenchrus tribuloides. 
Commelina virginica. 
Cristatella erosa, 
Croton texensis. 
Cycloloma atriplicifolium. 
Cyperus schweinitzii. 
Eragrostis oxrylepis. 
Eriogonum annuum. 
Eriogonum longifolium. 
Euphorbia geyeri. 
Frelichia floridana. 
Gilia aggregata. 
Heliotropium convolvulaceum. 
Hymenopappus flavescens. 
Mentzelia multiflora. 
Parosela aurea, 
Parosela lanata. 
Pentstemon albidus. 
Polanisia trachysperma. 
Polypteris hookeriana. 
Sporobolus eryptandrus. 
