104 PLANT T.IKK oK ALABAMA, 



t A.MI'RSTKIAN I'l.ANT AKSOCI ATIONS. 



Huhi jtntii'its. '\\\v ciiiinciiccs of llic lower swells of the phiin with 

 the strata of the liineslone near the sui-face and destitute, of ar))oreal 

 growth are called hald prairies. Win re\ er the soil is not too shallow 

 to he cultivat^^d, these op(Mi })i-airie lands are devoted to the i)rodu<'- 

 tion of ctjrn, oats, or forage crops, and oidy the poorest spots remain 

 in the original state. These hald prairies can he regarded as the true 

 home of the original camp(\strian flora, wiiicli is peculiai" to a calcare- 

 ous soil rich in hunuis and with a sunny I'xposure. Many of its typos 

 are hold in connnon with the plant associations prevalent on the grassy 

 timhorle.ss plains of eastern North America. Those ty])os have spread 

 all over the crot^icoous depression wherever the forest has heen 

 removed, and find I'ofuge also on the herders of fields and woods, and 

 in waste places and a])andoned grounds. Of grasses the following are 

 most common in the open, except the last two, which prefer sheltered 

 borders: 



Paspaluiii kteve.^ Eragroatis capillariit.^ 



Paspalum distlchum. Eragrostis refrarla.^ 



Panicum flexile. ' Eragrostis purxh il. ' 



Panlcum antuvmale.^ Poa compreifm.^ 



Aiidrupogon furcalu.s. ' Elymus virginicuH. ' 



SiegUngla seslerioides.^ Broinus unioloides. 



Bouteloua curtipendtda.^ l^niola latifoUu. 



The following introduced and advcntive weeds invade cultivated 

 grounds, the last two named ineradicable and seriously iniurious to 

 the crops: 



Paspalum dUatatwn. Surghutn hnleperm'. 



Eleusine indica.^ Cypeni>t ml and as. 



Sorghum sativum. 



Associated with the grasses are the following species widely distrib- 

 uted in the open of the Carolinian area: 



Hypericum sphaerocarpum.^ Verbena anguslifolia.^ 



Kuhnistera Candida.^ Verbena canadensis {V. aubfe(ia).^ 



Kuhnistera purpurea.^ Eupatoriiun altissimum (rare).^ 



Acuan illinoensis.^ Euputorium serotinum.^ 



Cassia multipinnata.^ Silphium ladniatum.^ 



Polygala mariana.^ Siiphium, scaberrirnum.^ 



Limun siUcatitm.^ Siiphium trifoUatuni.^ 



Euphorbia diclyosperma.^ Hrauneria pallida.^ 



Onagra biennis.^ Rndbeckia trilobata.^ 



Gaura michauxii.^ Helianthus hirsutus.^ 



Polytaenia nuttallii.^ Helianthus divaricatus.^ 



Asclepias obovata.^ Coreoptsis lanceolata.^ 



Asclepiodora viridis. Lepachys pinnata. ' 



Heliotropium tenellum. Mesadenia plantaginifolia.^ 

 Myosotis vema. 



^ Also found north of the Central Pine belt. 



