harper: PHYTOGEOGRAPHY of southern MARYLAND 585 



de\'eloped between that and the Patuxent Ri\-er. The same or 

 similar geological formations extend northeastward nearly to 

 New York, making fairly fertile soils all the way, but east of 

 Chesapeake Bay the topography and vegetation are somewhat 

 different. 



The soils are largely, if not mostly, derived from Pleistocene 

 material, and are loamy sands, fine sandy loams, etc. In some 

 places, particularly near Upper Marlboro, the greensand comes 

 to the surface and gives the soil a decided greenish yellow tinge, 

 which is a very rare color for soils. On the whole the soils are 

 rather above the average in fertility. 



The topograph}' is a little less hilly than that of the fall-line 

 hills, and there are more flat areas, but small rounded knolls or 

 knobs averaging perhaps 500 feet in diameter and 15 or 20 feet 

 high are very characteristic, even in some of the valleys sepa- 

 rated from the main body of the greensand. 



The region has been extensively farmed for over 200 years, 

 and the forests reduced to a little less than a third of the area. 

 Xisarly all are second growth, but a few magnificent original 

 stands of yellow poplar, white oak, etc., have been preserved.^ 

 Evergreens constitute not more than 10 per cent of the total, 

 and as the prevailing evergreen is the scrub pine, which is partial 

 to worn-out fields, etc., we may infer that the original forests 

 were almost wholly deciduous. 



The commonest trees at present seem to be as follows: 



Liriodendron hdipifera. Poplar. v Quercus velutina. Black oak. 



E Pinus virginiana. Scrub pine. Nyssa sylvatica. Sour gum. 



Quercus alba. White oak. *Fraxinus americana. Ash. 



Acer rubrum. Red maple. *Quercus borealis ^naxima^ Red oak 



*Fagus grandifolia. Beech. (northern). 



*Betula nigra. Birch. Quercus palustris. Pine oak. 



Castanea dentata. Chestnut. Hicoria alba. Hickory. 



Liquidambar styracifiua. .Sweet gum. Quercus f ale al a. Red oak (southern). 



*Ulmus americana. Elm. Mor^lS rubra. Mulberry. 

 *Platanus occidenialis. Sycamore. 



Any one familiar with the habitats of these trees will notice a 

 great contrast between the starred ones in this list and the pre- 



« For the location of some of these see map of Prince Georges County in Bes- 

 ley's forest report previously mentioned. 



^ Formerly referred to Q. rubra. See Torreya 17: 135. 1917. 



