1921] PALMER. THE FOREST FLORA OF THE OZARK REGION 225 



mardii var. Schneckii Sarg., Celtis laevigata var. texana Sarg., Fraxinus 

 americana L., Bumelia lanuginosa Pers., Rhus trilobata Nutt., Ilex decidua 

 Walt., Rhamnus lanceolatus Pursli and Viburnum rufidulum Raf. In 

 the protection of the limestone terraces is also sometimes found Berchemia 

 scandens K. Koch, and on the more exposed ledges Salix humilis Marsh, 

 Ceanothus ovatus var. puhescens and Andrachne phyllanthoides Muell. 



Arg. 



Q 



Q 



ana Buckl. of the limestone hills of Texas, and the presence of the Celtis and 

 Andrachne, both characteristic species of the southwest, together with 

 Cotinus americanus, growing on high bluflFs in close proximity, and many 

 herbaceous species common to both regions, are certainly significant. Two 

 of the plants in the above list are so interesting, indeed, as to deserve fuller 

 mention. The occurrence of Andrachne phyllanthoides, the only woody 

 representative of the large family Euphorbiaccac, to which belong so many 

 of the shrubs and trees of the arid southwest and of the tropics, in the 

 central Mississippi Valley, is quite remarkable In the Ozark region this 

 curious and pretty little shrub is restricted to the rocky barrens and ledges 

 of the open hills and to the low bluffs and gravelly beds of the dividing 

 streams; in Texas it usually grows along small, intermittant streams, on 

 the gravel-bars and shingle, where it is occasionally swept over and 

 irrigated by freshets and floods. The American Smoke-tree {Cotinus 

 americanus) appears to be restricted to the vicinity of ^Yhite River and 

 some of its tributaries, in the Ozark region. Here it grows generally 

 along open rocky bluffs, and is sometimes truly arborescent, attaining a 

 maximum height of six or eight metres. In the dryer region of western 

 Texas it is always shrubby, and seeks the protection of steep hillsides 

 and ravines. The list of herbaceous plants common to the two regions, 

 while not very long in identical species, is,nevertheless, remarkable enough, 

 including such plants as Lesquerella gracilis S. Wats.?, Evolvulus pilosus 

 Nutt., Eriogonum hirsutum Nutt., Oenothera missouriensis Sims, Pcnt- 

 stemon Cobaea Nutt.. Stenosiphon linijolius Britt., Erythraea calycosa 

 Buckl., E. icxensis Griseb., and Marshallia caespitosa Nutt. Almost 

 equally important are many other plants of common genera and closely 

 allied species inhabiting both the Ozark barrens and the Edwards pla- 

 teau; some of them are so similar that there is some diversity of opinion 

 as to whether they are really identical or should be treated as distinct 

 species or varieties; a fact not without significance in its bearing upon the 



antiquity of the Ozark flora. 



The singular! tv of these eroded, treeless hills in the midst of a generally 

 forested region has always attracted the attention of travellers, and the 

 name of bald knobs was applied to them at an early day, a name which 

 later attained some ill fame from the deeds of certain bands of outlaws 

 which once infested the country, the members being known as "Bald- 

 knobbers" from the fact that they are said to have held their secret 

 meeting on the tops of some of the highest "balds." The country, 



