207] FLORA OF COLUMBIA AND VICINITY 65 



D. CoLLiNAE. Plants of dry hills. * .i 



The dry hill flora has slight importance in the region. It 

 occurs on dry knolls and hillocks in the woods, and on sterile 

 hill-slopes. There are two slight associations, one the ordinary 

 sylvan, or thicket, xerophytic association, the other a solitary, 

 but interesting, one on a hillside just beyond Hinkson creek on 

 the Ashland road. 



a. CoUinae antennarioides. The cat's-foot association 

 of plants on dry knolls and hillocks consists of patches of An- 

 tennaria campestris, A. neglecta, A. plantaginifolia, Comandra 

 umbellata, Carex Leavemvorthii, C. cephalophora, C. cephaloi- 

 dea, C. Muhlenhergii Xalapensis, Panicuni depauperatum, P. 

 Enslini, P. implicatum, Danthonia spicata, Festiica Shortii, and 

 F. octoflora. 



b. Collinae opuntioides. The prickly pear association 

 of plants on dry hillsides occurs only on a hill on the Ashland 

 road between Hinkson and Grindstone creeks. It consists of 

 the prickly pear {Opuntia Rafinesquii), Verbena Aubletia, Ble- 

 philia ciliata, Teiicrium Canadense, Croton capitatus, and C. 

 monanthogynus. Besides these there is the flora usual to dry 

 open thickets. 



IV. PABASITES ET SAPROPHYTES. PARASITIC ANB 

 SAPROPHYTIC PLANTS. 



Besides the parasitic and saprophytic fungi, there are also 

 a few parasites and saprophytes among the flowering plants. 

 The most important of these parasites, ecologically, are the dod- 

 ders {Cuscuia Gro?iovn, C. tenuiflora, and C. Polygmwrimi). 

 These are common in all low grounds. Orobanche uniflora is 

 rare in thickets, and Monotropa uniflora, saprophytic on leaf- 

 mould, is scarce in rich woods. Certain other plants of ordinary 



5. 



