205] FLORA OF COLUMBIA AND VICINITY 63 



Ceanothus pubescens Heliopsis scabra 



Hypericum pseudomacu- Rudbeckia purpurea 



latum R. pinnata 



Taenidia integerrima Helianthus hirsutus 



Koellia Virginica Krigia amplexicaulis 

 Gerardia grandiflora 



C. Steriles. Plants of barrens. 



Barrens in the vicinity of Columbia are in the main re- 

 stricted to a few red clay hills, which lie near the cliffs. Upon 

 them grow a typical xerophytic vegetation. A like flora is 

 found also on certain hilltops with a rocky soil. Besides the red 

 clay barrens there are a few sterile tracts along roads and rail- 

 roads, especially where the surface soil has been removed. 



a. Steriles lecheoides. The pinweed association of 

 plants upon sterile red clay hills lies mainly next the cliffs. The 

 two best examples are found, the one immediately south of the 

 Hinkson ford on the Black's Mill road, the other near the Hink- 

 son bridge on the Ashland road. Portions of Pansy Hill have 

 a similar flora. The turf of these barrens is composed mainly 

 of Lechea tenuifolia and Cladonia (spp.), but there are also thin 

 swards of Danthonia spicata, Aristida oligantha and A. basi- 

 ramea. The bird's-foot violet {Viola pedata), the violet wood 

 sorrel {Oxalis violacea), and the hoary puccoon {Lithospermum 

 canescens), are the commonest vernal plants. In summer 

 Stylosanthes hiflora, Poly gala verticillata, Ruellia ciliosa, Liatris 

 intertnedia, Cassia Chamaecrista, and Phaseolus helvolus are 

 abundant. The autumnal plants comprise the bush-clovers {Les- 

 pedeza spp.), Gerardia asperula, G. Besseyana, and Solidago 

 longipetiolata. There is often a marked mixture of prairie 

 elements. Bouteloua racemosa has become established in a few 



