104 PLANT LIFE OF ALABAMA. 



CAMPESTJRIAN PLANT ASSOCIATIONS. 



Said 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 calcare- 

 ous soil rich in humus and with a sunny exposure. Many 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. 1 Eragrostis capillaris. l 



Paspcdum distichum. Eragrostis refracta. 1 



Panicum flexile. l Eragrostis purshii. l 



Panicum autumnale. l Poa compressa. l 



Andropogon furcaius. 1 Elymus virginicus. 1 



Sieglingia seslerioides. 1 Bromus unioloidex. 



Bouteloua curtipendula. 1 Uniola latifolia. 



The following introduced and adventive weeds invade cuHivated 

 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 sphaerocarpum. ' Verbena angustifolia. l 



Kuhnistera Candida. 1 Verbena canadensis ( V. aubletia) . l 



Kuhnistera purpurea. ' Eupatorium altissimum (rare) . l 



Acuan illinoensis. 1 Eupatorium serotinum. 1 



Cassia multipinnata. 1 Silphium ladniatum. 1 



Poly gala mariana. 1 Silphium scaberrimum. 1 



Linum sulcatum. l Silphium trifoliatum . l 



Euphorbia dictyosperma. l Brauneria pallida. l 



Onagra biennis. 1 Rudbeckia trilobata. 1 



Gaura michauxii. 1 Helianthus hirsutus. 1 



Polytaenia nuttallii. 1 Helianthus divaricatus. 1 



Asckpias obovata. 1 Coreopsis lanceolata. 1 



Asclepiodora viridis. Lepachys pinnata. 1 



Heliotropium teneUum. Mesadenia plantaginifolia. 1 

 Myosotis verna. 



1 Also found north of the Central Pine belt. 



