Prairie- and Sand Hill District. 531 
western Louisiana to San Antonio Bay and irregularly beyond. These prairies 
are characterized by a rich growth of grass and many flowering plants and 
spreading trees of Ouercus virens (= O. virginiana) drooped with 7illandsia 
usneoides border the grassland '). 
According to BRAY*) the pronounced xerophytic aspects of this grass- 
land vegetation are due to the occurrence of summer drouths indicated by 
the occurrence of perennial roots storage tubers, bulbs etc. The associates 
of the grasses are so numerous that for some weeks during spring, these flowe- 
ring plants may quite overshadow the grasses so that the prairiers are brilliant 
with color. 
The following prairie annuals occur in great abundance: Draba cuneifolia, pn 
Nuttallianus, A. Lindheimeri, Lupinus texensis, Euphorbia ge Croton corymbulosus, C, texen 
Gaura suffulta, Monandra ceitriodora, Centaurea americana, Evax prolifera, Gaillardia Deicheile, 
Gutierrezia texana, Hymenopappus corymbosus, Babe Berge he perennials wit 
roots and tubers of various structural adaptations are Yucca rupicola, Krameria secundiflora, 
Aukragälis alleine A. mexicanus, Indigofera Ze Psoralea se ta, Stillingia sylva- 
tica, Oeno mannia) speciosa, Zee odora decumbens, Salvia farinacea, S. azurea, 
Pentstemon Fr Oeiifite foetidissima, Lygodesmia Beer kaefh with such bulb plants 
as Allium Nuttallii, Nothoscordum kn (= N. bivalve), Androstephium violaceum, Zephyranthes 
texana, Cooperia Drummondi, C. pedunculata. 
Loess Mound Formation. The loess mounds on which a peculiar flora 
grows parallel the Missouri River in Missouri and Iowa. There is a heavy 
belt of timber back of the mounds and back of this is a high rolling prairie. 
Between the mounds and the river is a fertile gumbo bottom-prairie. 
Where the south and west side are steep and a BER are found such plants as 
Yucca angustifolia, Gaura coccinea, Psoralea argophylla, Sporobolus airoides; where they descend 
gradually to the bottom are Pentstemon grandiflorus, ink Pe rus, Dalea enneandra 
(= Dalea taxiflora), while on the north are pockets running up the sides of the mounds covered 
with dwarfed trees and shrubs: Corylus virginiana, Rhus glabra, Salix humilis. The tops of te 
mounds present a denuded appearance and of considerable elevation and upon them grow Castil- 
leia BERUNOEN Psoralea argophylla, Gaura coceinea, Glyeyrrhiza lepidota, Yucca ee 
airoides, Anemone eylindrica, Liatris punctata, Bouteloua hirsuta, Dalea 
Lithospermum angustifolium (= L. linearifolium), Lygodesmia juncea, Lactuca pulchella ai ze 
modium molle3). 
b) The Sand Hill Territory. 
The sand hills extend from Nebraska into the Dakotas on the north 
Kansas, Oklahoma, Indian Territory and Texas on the south and into 
northeastern Colorado. Some sand hill species enter the level prairies: 
Aristida basiramea, A. oligantha, Carex stenophylla, C. stipata, Cyperus 
1) BaıLey, VERNON: Biological Survey of Texas. North ‘American Fauna No. 25 US. 
Biological Survey 1905, 19. 
Distribution and Adaptation of the Vegetation of Texas. Bulletin Dalversiiy of Texas 
2) 
No. 82 Scientific Series No, 10 1906: 86. 
3) Busn, B. F.: Notes on the mound Flora of Atchison County, Missouri. 6th Su Mo, 
Botanic Garden. 121. 
34* 
