2 PREFACE. 



The increasing interest that is taken in the study of the 

 Cellular Cryptogams, and the desire to encourage it, have led 

 to the inclusion again of the Hepaticse, which were omitted 

 in the last edition. These have been prepared through the 

 kindness of Prof. L. M. UNDERWOOD, though the limits of 

 the volume have necessitated somewhat briefer descriptions 

 than he considered desirable. The three fine plates illustrat- 

 ing the genera of these Orders, which were used in the early 

 editions, are also added, with a supplementary one, as well as 

 an additional one in illustration of the Grasses, thus increasing 

 the number of plates to twenty-five. A Glossary of botanical 

 terms is appended, to meet an expressed need of those who 

 use the Manual alone, and a Synopsis of the Orders in their 

 sequence is given, to contrast more clearly their characters, and 

 to show the general principles which have determined their 

 present arrangement. This should be a useful adjunct to the 

 more artificially arranged Analytical Key. 



GEOGRAPHICAL LIMITS, AND DISTRIBUTION. The southern 

 limit of the territory covered by the present work is the same 

 as in the later previous editions, viz. the southern boundary of 

 Virginia and Kentucky. This coincides better than any other 

 geographical line with the natural division between the cooler- 

 temperate and the warm-temperate vegetation of the Atlantic 

 States. The rapid increase of population west of the Missis- 

 sippi River, and the growing need of a Manual covering the 

 flora of that section, have seemed a sufficient reason for the 

 extension of the limits of the work westward to the 100th 

 meridian, thus connecting with the Manual of the Flora, of the 

 Rocky Mountain Region by Prof. Coulter. These limits, as 

 well as that upon the north, have been in general strictly 

 observed, very few species being admitted that are not known 

 with some degree of certainty to occur within them. The ex- 

 treme western flora is no doubt imperfectly represented. 



The distribution of the individual species is indicated some- 

 what more definitely than heretofore in many cases, so far as 

 it could be satisfactorily ascertained. The extralimital range 

 is also sometimes given, but the terms "northward," "south- 

 ward," and " westward " are more frequently employed, signi- 

 fying an indefinite range in those directions beyond the limits 

 of the Manual. Where no definite habitat is specified, the spe- 



