302 THE PLANT LIFE OF MAEYLAND 



istic of perhaps a hundred other species. Still other species are 

 wide-spread in occurrence but are much more abundant in certain 

 sections of the state where soils of a partcular character are pre- 

 dominant. For example, in the counties of Southern Maryland the 

 Dwarf Dandelion (Adopogon carolinianum) , the Blue Toad-flax 

 (Linaria canadensis) and the Ipecac Spurge (Euphorbia ipecacu- 

 anhae) are three native plants which are among the most charac- 

 teristic weeds in old fields with sandy or sandy loam soil. The Gum 

 Succory (Chondrilla juncea) is common in certain localities in 

 Southern Maryland and at a few places on the Eastern Shore, where 

 it grows on light soils. It is a plant which is restricted in its oc- 

 currence rather because of the recentness of its introduction than 

 because of particular life requirements. The Yellow Horned Poppy 

 (Glaucium glaucium) is an adventive plant which is confined to 

 the sandy beaches of the Chesapeake and is one of the few intro- 

 duced plants restricted to a definite natural habitat. 



Particular attention was given during the field work throughout 

 the state to the occurrence of the Viper's Bugloss (Echium vulgare ) 

 and the Great Mullein (Verbascum tliapsus). Both of these were 

 observed in every county of the state and on a wide range of soils 

 from the shale-derived loams of Allegany County and the lime- 

 stone clays of Washington County to the sandy loams and sands of 

 the Eastern Shore. Both plants were noticed to be much more com- 

 mon in fields that had lain fallow for several years, because of their 

 biennial habit. Much of the reputation that these plants have as 

 soil indicators is due to the fact that fields which have become "run 

 down" are allowed to lie in pasture for several years, these weeds 

 then have time to develop and the fact that they are not eaten by 

 the stock leaves them conspicuous over the field. 



The spontaneous occurrence throughout the Midland section of 

 the state of the Kentucky Bluegrass (Poa pratensis) and other turf- 

 forming grasses is an evidence of the freedom of soil water move- 

 ment into the surface layers of the soil occupied by the roots of 

 these grasses. Throughout the sandy soils of the Coastal Plain, as 

 in the states to the south, the maintenance of a close sod of such 

 grasses is difficult, and their occurrence indicates that the physical 

 character of the soil has been modified by artificial treatment in the 



