66 BULLETIN OF THE 



posed to exist, but which cannot be found, should stand in the cat- 

 alogue to be apologized for to those who would be.glad to obtain 

 them. A few species, however, which are positively known to have 

 once occured within our limits, but which have been obliterated 

 within the recollection of persons now living, have been retained, 

 as well as several of which only a single specimen has been found ; 

 but in all such cases the facts are fully stated in the notes accompany- 

 ing each plant. 



Range of the Local Flora. 



The extent of territory which has of late years been tacitly recog- 

 nized by botanists here as constituting the area of what has been called 

 the Flora Columbiana is limited on the north by the Great Falls of 

 the Potomac, and on the south by the Mount Vernon estate in Vir- 

 ginia, and Marshall's just opposite this on the Maryland side of the 

 river, while it may reach back from the river as far as the divide 

 to the east, and as far westward as the foot of the Blue Ridge, so as 

 not to embrace any of the peculiarly mountain forms. Practically, 

 however, the east and west range is much more restricted and only 

 extends a few miles in either direction. 



Comparison of the Flora of 1830 with that of 1880. 



Washington and its vicinity ha9 long been a field of botanical 

 research. The year 1825 witnessed the dissolution of the Washington 

 Botanical Society, which had for many years cultivated the science, 

 and the same year also saw the formation of the Botanic Club, which 

 continued the work, and in one respect, at least, excelled the former 

 in usefulness, since it has handed down to us of the present gen- 

 eration a valuable record in the form of a catalogue of the plants 

 then known to exist in this locality. This catalogue, which was 

 fittingly entitled Florae Columbiance Prodromus, and claimed to 

 exhibit " a list of all the plants which have as yet been collected," 

 though now rare, and long out of print, is still to be found in a few 

 botanical libraries. 



I have succeeded in securing a copy of this work, and have been 

 deeply interested in comparing the results then reached with those 

 which we are now able to present. A few of these comparisons are 

 well worth reproducing. 



It should be premised that the Prodromus is arranged on the 



