104 PLANT LIFE OF ALABAMA. 
CAMPESTRIAN PLANT ASSOCIATIONS. 
Bald prairies.—The eminences of the lower swells of the plain with 
the strata of the limestone near the surface and destitute of arboreal 
growth are called bald prairies. Wherever the soil is not too shallow 
to be cultivated, these open prairie lands are devoted to the produc- 
tion of corn, oats, or forage crops, and only the poorest spots remain 
in the original state. These bald prairies can be regarded as the true 
home of the original campestrian flora, which is peculiar to a caleare- 
ous soil rich in humus and with a sunny exposure. Man y of its types 
are held in common with the plant associations prevalent on the grassy 
timberless plains of eastern North America. These types have spread 
all over the cretaceous depression wherever the forest has been 
removed, and find refuge also on the borders of fields and woods, and 
in waste places and abandoned grounds. Of grasses the following are 
most common in the open, except the last two, which prefer sheltered 
borders: 
Paspalum laeve.' Eragrostis capillaris. | 
Paspaluin distichum. Eragrostis refracta.! 
Panicum flexile. Eragrostis purshii 
Panicum autumnale.' Poa compressa.! 
Andropogon furcatus.' Elymus virginicus.' 
Sieglingia seslerioides.} Bromus unioloides, 
Boutelowa curtipendula.' Uniola latifolia, 
The following introduced and adventive weeds invade cultivated 
grounds, the last two named ineradicable and seriously injurious to 
the crops: 
Paspalum dilatatum. Sorghum halepense. 
Eleusine indica.' Cyperus rotundus. 
Sorghum sativum. 
Associated with the grasses are the following species widely distrib- 
uted in the open of the Carolinian area: 
Hypericum sphaerocarpuim.' Verbena angustifolia. 
Kuhnistera candida.) Verbena canadensis (V. aubletia) 
Kuhnistera purpurea.' Eupatorium altissimum (rare) .} 
Acuan illinoensis.' Eupatorium serotinum.) 
Cassia multipinnata.! Silphium laciniatum. 
Polygala mariana.' Silphium scaberrimum.! 
Linum sulcatum.' Silphium trifoliatum.! 
Euphorbia dictyosperma.} Brauneria pallida. 
Onagra biennis.! Rudbeckia trilobata,' 
Gaura michauxii.! Helianthus hirsutus.} 
Polytaenia nuttallii.! Helianthus divaricatus.} 
Asclepias obovata.! Coreopsis lanceolata.} 
Asclepiodora viridis. Lepachys pinnata.! 
Heliotropium tenellum. Mesadenia plantaginifolia 
Myosotis verna. 
' Also found north of the Central Pine belt. 
