1921] PALMER, THE FOREST FLORA OF THE OZARK REGION 223 



of trees and with a peculiar prairie flora. White Oak, Post Oak, Black 

 Jack and the Hard-shell Hickories {Carya alba K. Koch, C. Buckleyi var. 

 arhansana Sarg. and var. villosa Sarg.) are amongst the commonest trees 

 and often almost the only ones found over considerable areas. The 

 unforested openings of the Ozark plateau vary greatly in character and 

 extent; they may be conveniently classed under two heads: prairies, 

 and rocky barrens, although these sometimes intergrade and the peculiar- 

 ities of both may be present in close proximity. Some of the larger 

 prairies are several miles across, but they are usually much smaller, and 

 remnants of a typical prairie flora still cling in places to open rocky hill- 

 sides entirely surrounded by the forest. Such areas are often only a few 

 rods in extent. The term barrens is sometimes used colloquially in the 

 Ozarks to designate the larger prairies, but is here restricted to the limited 

 rocky areas with a quite distinct flora described later. The prairie open- 

 iags are so well marked and so impressed the early settlers that many of 

 them were given definite names such as "Cowman's Barrens," "Diamond 

 Frairie" and "Round Prairie," While in some of the smaller prairies 

 the sterile nature of the soil seems to have placed a check upon the ad- 

 vance of the forest, as in the rocky barrens, in many of the larger ones its 

 fertility is quite equal to that of the surrounding woodlands, and the 

 explanation of their origin or preservation must be sought elsewhere. 

 The more fertile portions of these natural "c'earings" were for obvious 

 reasons attractive to settlers, and if not too remote from a natural water 

 supply were early brought under cultivation. Consequently the prairie 

 flora has usually been preserved fully only in the smaller and more rocky 



areas. 



Glades and rocky barrens occur wherever solid strata are exposed on 



level or gently sloping surfaces. They are most abundant in the lime- 

 stone regions, but are sometimes formed upon outcrops of chert, sand- 



In extent they seldom exceed a 



stone, granite, riolite or beds of clay, 

 few acres without interruption, and are generally quite small. In such 

 places frequently a few bushes or stunted trees occur along ledges and 

 fissures or in depressions where there is some accumulation of soil and 

 moisture, and sometimes they form clumps upon mounds which are often 



a feature of the barrens. 



Q 



Muenchh. and Bumelia lanuginosa Pers. are commonly found, although 



seldom of arborescent size 



trjfoliata 



and Viburnum rufidulum Raf. are typical shrubs. But over the more 

 exposed portions the flora is entirely herbaceous, consisting of a few 

 bulbous Liliales and fleshy perennials, such as Camassia csciilenta Lindl., 

 Allium stellaiuvi Ker, Agave virginica L., Tragia ramosa Torr., species 

 of Allioma, Talinum and Opuntia, and a variety of annuals. Plants of 

 the last class are by far the most numerous and make up the bulk of the 

 floral population. Every little depression cleft or spot where there is 

 even the thinnest accumulation of soil is occupied by some, and they cling 

 tenaciously to such vantage points and struggle for their possession, 



