16 PREFACE. 



thoroughly naturalized, and the adventive ; the first comprising those 

 species which have made themselves perfectly at home in this coun- 

 try, propagating themselves freely by seed beyond the limits of 

 cultivated grounds ; the second, those which are only locally spon- 

 taneous, and perhaps precarious, or which are spontaneous only in 

 cultivated fields, around dwellings, or in manured soil, and w r hich, 

 still directly or indirectly dependent upon civilized man, would 

 probably soon disappear if he were to abandon the country. (I 

 here rank with the adventive plants those weeds of cultivation which 

 De Candolle terms plants cultivated without or against man's will.) 

 Accordingly the species naturalized from Eiirope are indicated, at 

 the close of the paragraph, by the phrase " (Nat. from Eu.) " : those 

 adventive, or less established, by the phrase " (Adv. from Eu.)," &c. 

 Distinction of Grade of Varieties. Vain is the attempt 

 to draw an absolute line between varieties and species. Yet in sys- 

 tematic works the distinction has to be made absolute, and each par- 

 ticular form to be regarded as a species or a variety, according to 

 the botanist's best judgment. Varieties, too, exhibit all degrees of 

 distinctness. Such as are marked and definite enough to require 

 names are distinguished here into two sorts, according to their grade: 

 1. Those which, I think, cannot be doubted to be varieties of the 

 species they are referred to, have the name printed in small capi- 

 tals.* These varieties make part of the common paragraph. 2. Those 

 so distinct and peculiar that they have been, or readily may be, 

 taken for species, and are some of them not unlikely to establish the 

 claim : of these the name is printed in the same type as that of the 

 species ; and they are allowed the distinction of a separate para- 

 graph,t — except where the variety itself is the only form in the 

 country, as in the first species of Anemone. $ 



. -*. As, for instance, the three varieties of Lespedeza violacea, p. 137, viz. diver- 

 gens, sessilifolia, and angustifolia. See also, under Ranunculus Flam- 

 mula, var. intermedius, p. 41. 



t As, Var. reptans, of the above-mentioned species. 



X A. patens, L., var. Nuttalliana, p. 36. 



