Vlll PREFACE. 



in question occurs in the States south of Virginia or Kentucky. Thus 

 Magnolia glauca, p. 16, a prevailingly Southern species, but which is spar- 

 ingly found as far north as Massachusetts, is recorded as growing " near 

 Cape Ann and New York southward, near the coast"; M. acuminata, 

 "W. New York, Pennsylvania, Ohio, and southward"; &c. While in 

 species of northern range, the southern limits are mentioned ; as, Nuphar 

 Kalmiana, p. 23, " New England, New York, and northward"; Cardamine 

 pratensis, p. 33, " Vermont to Wisconsin, northward," &c. And so of 

 Western plants; e.g. Isopyrum biternatum, p. 11, " Ohio, Kentucky, and 

 westward " ; Psoralea aryophylla, p. 94, " Wisconsin and westward " ; 

 Amorplia canescens, p. 95, " Michigan to Wisconsin, and south westward." 

 2. Where no habitat or range is mentioned, the species is supposed to be 

 diffused over our whole area, or nearly so, and usually beyond it. 3. When 

 the species is of local or restricted occurrence, so far as known, the special 

 habitat is given ; e. g. Vesicaria Shortii and V. Lescurii, p. 38; Sullivantia 

 Ohionis, p. 144, &c. Except in such cases, the want of space has generally 

 demanded the omission of particular localities, which are so appropriate 

 and so useful both in local Floras and in more detailed works, but for 

 which there is no room in a manual like this. 



For the same reason, I could not here undertake to specify the range of 

 those species which extend beyond the geographical limits of this work, or 

 beyond the United States. Nevertheless, to facilitate the comparison of 

 our flora with that of Europe, I have appended the mark (Eu.) to those 

 species which are indigenous to both. 



Foreign plants which have become denizens of the soil are of course enu- 

 merated and described along with the genuine indigenous members of our 

 flora ; but the introduced species are distinguished by the specific name be- 

 ing printed in a different type, namely, in small capitals (e. g. Ranunculus 

 ACEIS, p. 10), while the names of the indigenous species are in full-face 

 letter (e. g. R. repeiis). Moreover, the country from which they were 

 introduced is specified (mostly Europe), as well as the nature of the deni- 

 zenship. That is, following the suggestions of M. Alphonse De Candolle, 

 I have classified our introduced plants as well as I could into two sorts, the 

 thoroughly naturalized, and the adventive ; the first comprising those species 

 which have made themselves perfectly at home in this country, propagating 

 themselves freely by seed beyond the limits of cultivated grounds ; the sec- 

 ond, those which are only locally spontaneous, and perhaps precarious, or 

 which are spontaneous only in cultivated fields, around dwellings, or in 

 manured soil, and which, still dependent upon civilized man, would prob 

 ably soon disappear if he were to abandon the country. (I here rank with 

 the adventive plants those which De Candolle terms plants culti/ated with- 

 out or against man's will.) Accordingly the species naturalized from Europe 

 are indicated, at the close of the paragraph, by the phrase " (Nat. from 



