wherry: reactions of soils 589 



which flatten out toward tidewater. But on some of the divides 

 in St. ]VIarys County there are a few small shallow ponds, hardly 

 large enough to show on topographic maps. The highest alti- 

 tude is about 180 feet. 



About half the area is in forest, but probably not more than 

 one-fourth is original forest. About 40 per cent of the trees are 

 evergreen. The prevailing species seem to be as follows: 



E Pinus virginiana. Scrub pine. Fagus grandifolia. Beech. 



*Qrtercusfalcata. Red oak (southern). Qiiercus marylandica. Black-jack oak. 



Quercus alba. White oak. E Juniperus virginiana. Cedar. 



Liquidamhar styraciflua. Sweet gum. Quercus phellos. Willow oak. 



Castanea dentata. Chestnut. Quercus montana. Chestnut oak. 



Quercus stellata. Post oak. Pinus echinata. Short-leaf pine. 



E *Pinus taeda. Loblolly pine. Quercus coccinea. Scarlet oak. 



lAriodendron tulipifera. Poplar. Platanus occidentalis. Sycamore. 



Quercus velutina. Black oak. Betula nigra. Birch. 



Acer rubrum. Red maple. Hicoria glabra. Hickory. 



Nyssa sylvatica. Sour gum. Ulmus americana. Elm. 



*Hicoria alba. Hickory. 



Oaks here make up a little more than one-thi^d of the forest. 

 The few species starred may prefer this region to the other four 

 simply because it is the southernmost and wannest, fcr they all 

 range much farther southward than northward. Among the 

 small trees or large shrubs Ilex opaca, Aralia spinosa, and Myrica 

 cerifera are much commoner here than in the other regions, 

 probably for the same reason. The smaller shrubbery dees not 

 differ much from that in regions 1 and 4. 



PLANT PHYSIOLOGY.— r/ie reactions of the soils supporting 

 the growth of certain native orchids. Edgar T. Wherry, 

 Washington, D. C. 



That soil reaction is an important factor in connection with 

 the growth of certain plants is now thoroughly established — 

 most legumes require an alkaline soil, most heaths an acid one, 

 and so on. It has seemed to the writer a matter of interest to 

 ascertain the relations in the case of some of the less widespread 

 native plants, and during vacation trips for several years past 

 tests have been made with this end in view. The results ob- 

 tained with the Orchidaceae are here presented. 



