Natural History of District of Columbia— McAtee 77 



Piedmont, in the preponderance of sandy and gravelly soils. 

 For instance, this region is the nearest to Washington, 

 where one can walk long distances in soft sandy roads— an 

 experience which on some of the hottest days makes a last- 

 ing impression concerning the geological and other peculiari- 

 ties of the Coastal Plain. 



As to the general flora of the area, the common oaks are 

 Quercus marilandica, stellata and alba. The pines include 

 Pinus rigida and virginiana, the latter more common ; chest 

 nut and chinquapin abound, as do also sweet gum, dogwood 

 and sassafras. The commonest shrubs are mountain laurel, 

 pink azalea, blueberries and huckleberries. Among the herbs, 

 Cypripedium acaule, Polygala incamata, Baptisia tinctoria, 

 Sarothra gentianoides and Ohrysopsis mariana are the most 

 characteristic of the indigenous species. The growth imme- 

 diately surrounding the Magnolia bogs includes red maple, 

 alder (Alnus rugosa), sour gum, holly (Ilex opaca) and 

 Pinus virginiana. 



The bogs are fringed, or dotted with clumps of Magnolia 

 virginiana, Myrica, swamp azalea, sheep laurel, Oaylussacia- 

 duni08a, Vaccinium corymbosum, Viburnum nudum and cas- 

 sinoides and other shrubs named in the subjoined list. 

 Around the bases of the shrub colonies are deep cushions of 

 sphagnum in which grow some of our showiest orchids as 

 Pogonia ophioglossoides and Limodorum. The open centers 

 of the bogs, or interspaces between the shrub islands give a 

 view of the surface stratum of these areas— the white gravel, 

 or gravel and sand, flush to the surface or slightly overflowed 

 with clear, cool spring water. In the water grow algae, and 

 the lycopods, Utricularia, Sundews. Xyria, Tofieldia and 

 many other of the plants mentioned below. On the slightest 

 elevations of the gravel are clumps of lichens of the genus 

 Cladonia, here growing in water, though elsewhere seen in 

 the dryest possible situations. 50 



M Bog ecologists have Invented a sublimated white ribbon conception of 

 physiologically dry water. This brand is so charged with bog extract, it 

 is alleged, that plants living in it do not imbibe so much as of the ordinary 

 kind, hence willy-nilly have a physiologically dry experience. This theory 

 will not serve to explain the presence of Cladonia in Magnolia bogs, how- 

 ever, as the water is constantly flowing and as free from matters in solu- 

 tion as is possible in natural waters. 



