20 ' PREFACE. 



vening ranges of Virginia and Pennsylvania partake 

 in part only of the same peculiarities, but the greater 

 elevation of some of our summits permits the growth 

 of some species which are unknown between them 

 and the Northern regions above mentioned. 



In the distribution of Plants over the State we 

 have three distinctly marked Districts, as well char- 

 acterized by their Flora as by their Geological feat- 

 ures. As in the Geology of the State the peculiar 

 formation of one District may penetrate, overlie, or 

 underlie that of another, yet the predominating char- 

 acters of each be sufficiently marked and striking to 

 arrest the notice of the most casual observer; so it 

 is with the vegetation of these Districts. The anal- 

 ogy of distribution between the objects of these sci- 

 ences may be extended still further. For as, in the 

 one case, we often meet with misplaced Rocks, so, in 

 the other, the Botanist is sometimes surprised by 

 meeting with species of Plants quite out of tlieir 

 proper range, and for whose location it is not always 

 easy to account. Thus the Cranberry^ an inhabitant 

 of elevated regions and not uncommon in our Moun- 

 tain Marshes, is also found, to a limited extent, in 

 the low lands of the Northeastern part of the State. 

 The beautiful Calico Bush^ or Ivy^ rarely found but 

 in rocky regions, as in the mountains or along the 

 rocky banks of watercourses, occurs abundantly in 

 the Dismal Swamp, especially along the line of the 

 Canal. The pretty Roanoke Bell (Mertensia Virgin- 

 ica), a native of the Mountains, is scattered along 



