Plants Occurring on Calcareous Rock Outcrops in 

 North Carolina 



Henry J. Oosting 



The soil preferences and ranges of acid or basic tolerance of 

 many plants are well known. Those species with extreme require- 

 ments are of special interest because their distribution is frequently 

 limited and they often occur sparsely or only locally within their 

 ranges. Calcicoles, or plants which grow in calcareous habitats, 

 may be in the latter category, particularly when limestone is rare 

 or absent. 



Limestone outcrops and calcareous soils are infrequent and 

 widely isolated in North Carolina and, where they occur, are 

 limited in extent. It would thus seem of interest to know some- 

 thing of the species associated with these areas and especially to 

 determine whether calcicolous species are uniformly present when 

 the habitats are so small and widely isolated. The state has been 

 included in the reported ranges of several calcicoles but, of those 

 species which are thought to be definitely restricted to calcareous 

 habitats, there are few specimens on record. These same species 

 are far more abundant in Tennessee, often in counties contiguous 

 with the North Carolina line, for limestone is common on the Ten- 

 nessee side of the Great Smoky Mountains. 



With the objective of determining the species associated with the 

 limestone and of adding new taxonomic records for North Caro- 

 lina, as many calcareous habitats were visited as possible. Con- 

 siderable difficulty was experienced in locating the usually small 

 and isolated stations. Soil maps, available for only scattered coun- 

 ties, indicated two stations. Otherwise outcrops were located by 

 chance. Inquiries concerning the sites of old lime kilns proved most 

 fruitful although they led to several unsuccessful searches as well. 

 Old quarries are all too frequently well below ground level and are 

 today filled with water with no limestone showing at the surface 

 in the vicinity. All of the calcareous outcrops visited, as well as 

 a few rumored localities not yet seen* are in or near the mountains. 

 Visits to shell-marl deposits in different parts of the Coastal plain 

 proved fruitless. Here the calcareous material is invariably buried 

 under several feet of acid soil. A few shell-marl strata were found 



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