Introduction 



sand bars across the mouths of small streams, thus forming natural 

 dams which partially or completely impound the water. These 

 "relic ponds" may be either brackish or fresh. Several of them are 

 shown on the Betterton and Chestertown sheets of the Geological 

 Survey maps. 



Behind the coastal dunes the so-called "dune hollows" are a 

 characteristic feature. These are shallow depressions in the sand, 

 kept more or less moist by rain water, which usually sinks out of 

 sight as it falls. They furnish interesting plant habitats. 



Transition Zone. On the Peninsula a number of northern plant 

 species reach their southern limits of natural distribution, at least 

 as far as the coastal region is concerned, while a still greater number 

 of species characteristic of the South extend no farther northward 

 than our area. Thus, the southernmost Coastal Plain stations for 

 Hemlock (Tsuga canadensis) are on the Peninsula, while two mari- 

 time plants of the North, Glaux maritima and Arenaria peploides 

 var. rohusta, are to be found on our shores, the latter also at Cape 

 Henry. The large white Trillium (T. grandiflorum) , rare on the 

 Coastal Plain, is found in astonishing abundance at two stations in 

 Cecil County, Maryland. According to J. K. Small (in "Peninsula 

 Delmarva") the Peninsula is also the southern Coastal Plain limit 

 for Gaultheria procumbens and Lycopodium lucidulum. 



A few characteristically southern species have barely gained 

 foothold on the southern tip of the Peninsula, where they are 

 limited to the southern half of Northampton County, Virginia. 

 Among these are the minute floating aquatic Wolffia punctata, as 

 well as Carex arenaria, Tillandsia usneoides (Spanish Moss), Quercus 

 virginiana (the Live Oak, which, as we have it, has more the stature 

 of a shrub than that of a tree), Teesdalia nudicaulis, and Ilex 

 vomitoria. 



Other species, extending somewhat farther north but limited to 

 the two Virginia counties, are Baptisia alba and B. pinetorum, 

 which occur locally in central Accomac County, Zanthoxylum 

 Clava-Herculis (the Toothache Tree), Berchemia scandens (Supple 

 Jack), and Borrichia frutescens (Sea Ox-eye), the last three reaching 

 their northern limit at Chincotaegue Island. Of southern trees, 

 the Sweet Leaf {Symplocos tinctoria) and Bald Cypress {Taxodium 

 distichum) are not known to occur north of lower Sussex County, 

 except that the latter has one station in Cape May County, New 

 Jersey. The Muscadine Grape (Vitis rotundifolia) reaches its 



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