Explanation of the Plan of the Catalogue. 



In the arrangement of orders Gray's Manual is followed, with one or 

 two exceptions for which the reason will be readily seen. The names of 

 the plants with their authorities are also from the same Manual as far 

 as they occur in that work, but when a name has been changed and the 

 new one has been accepted by botanists, that is used whenever such a 

 decision has come to the compiler's knowledge, and the Manual name is 

 added in parenthesis as a synonym. 



The names of species introduced into the United States are printed in 

 full-face type; some true natives of this country have evidently been in- 

 troduced into Nantucket, but that fact is indicated by some remark, and 

 not by change of type. 



Whatever is to be said of the nomenclature and classification of the 

 algse and the few other cryptogamous plants, will be found with those 

 orders in the body of the catalogue. 



The locality is given of species confined to a few spots or to one only; 

 when it is omitted it may be inferred that the plant is to be expected 

 wherever its natural habitat occurs. The locality of many others more 

 or less common is also mentioned for the aid of collectors. 



When no statement is made in regard to frequency of occurrence it is 

 to be understood that the plant is about as common as on the main land. 

 When "common" is added to a name, it means that the species is rather 

 prominent in the island flora. 



Localities are indicated in a general way; Bloomingdale, Hummock 

 Pond, &c., embrace the region about those places. 



Mr. Dame's discoveries are so numerous that I have marked them by 

 his initials only, "L. L. D." For the same reason those of Judge Church- 

 ill and Mr. Deane, when they have collected together, are marked "C. 

 & D." Those names without credit are of common plants, or else of 

 those which, somewhat rare, have yet been known for years and been ob- 

 served by all. 



Escapes from cultivation are very common in some of the streets of the 

 town; one may often see outside of a garden fence a petunia, a larkspur, 

 or a poppy, but these and many others are so plainly accidents of a sea- 

 son, that no record has been made of them. 



