48 I'l.ANT lAVK OF AI,.\I'. AMA. 



OI'KN-I.AND <>i; < AMri.Slia AN II.OKA ( \ I. K( »l'l I I 1 ,1 : I'l.AN'r ASSOCIATIONS.) 



Uiulcr :i iliiiiMtf so liit.'-lily t';i\ ()r:il>lr to t n-c u row t li and with soil 

 conditioiis which in ^^cncral present no ol)staclcs to the (ic\ clopincnt 

 of an arltorcal \c^'-clation, thci-c is in Alal)ania. as in the a<ljoinin<4" 

 States and the correspondinu- reL;i"iis ot' the Southei-n Athmtic St}it(\s, 

 hut litth' room hd't for the chai'acleiistic vegetation of open-phiin or 

 trtMdess mountain and hill coiuiti'v. es|)ecially if we exclude the vej^e- 

 tation of heili^ and luidershi'ulis of the open rolline- pine l)arfens. of 

 the pine Hats of the coast with their scattei'ed tree erowth, and of the 

 scantily shaded rocky crests of the, uiountains. It is only on the. coin- 

 parali\ely small tracts of the Cretaceous ])lain when*, the undorlying 

 limestone strata couie lu'ar tho surfaci' and tln^ coverin<r of the rich 

 black calcareous soil hecoiuos too shallow to pcu'mit the roots of tlie 

 trees to uain a linn hold, that arboreal vegetation is completely 

 (wcluded. In these localities — the so-called bald ]>rairies, low knolls, 

 or lu'oad swells of limited extent, with the soil not deep enoueh to be 

 plowed — many of the typical plants of the eastern North American 

 prairie have found a refuge, from which they have spread over the 

 bordei's of fields. o})en w^aysides, pasture^ and waste grounds, and worn- 

 out and abandoned lands. In such localities the ovioinal types have 

 to contend for the possession of the ground with many inti'oduced 

 and ad\entive weeds, the hardy oti'spring of species originating in the 

 exposed plain. Most of the native typical plants of these remnants 

 of the prairies, and of the open in general, are also common to the 

 prairies of the Mississippi Valley from the Wabash to the vallc}' of 

 the Colorado River in Texas. Most of the rosin weeds {SUphlum 

 laciniatum ^ etc.), species of sunflower {ILJianfJiKs)^ fleabanes {Kri- 

 geron)^ lludbeckias, and other tall, coarse composites are character- 

 istic of the prairie flora; most of the species of the pea family and 

 most of the umbellifers and grasses inhal)iting the prairies, open 

 borders of flelds, and pasture grounds in the central and northern 

 part of the State, have also their home on the prairies of Illinois, 

 Missouri, southern Ai'kansas, and eastern Texas. 



WATKIi AND SWAMl' FLORA (lIYDKOPHYTIC I'LANT ASSOCIATIONS). 



I'lantsof these associations are most prominently represented in the 

 lower ])ine region of the Coast plain. Among the 227 species of vas- 

 cular hydrophytes so far observed in Alabama 11 are pteridophytes, 

 139 species are monocotyledons, and 77 dicotyledons. 



HYDROCHAKIDKAX CLASS. 



Of hydrophytes floating free in w'ater. '.> species are known in the 

 State. They are kept afloat by their thallus or thallus-like stems, as 

 in AzoUa and duckweeds {Lemiia irdnm^ L. trlsulcata^ Spirodela)^ or 



