xii INTRODUCTION. VOL. I. 



rent English usage, as given in the chief English dictionaries from Walker's to the most 

 recent, and without reference to the supposed ancient pronunciation. 



Much diversity has been found in botanical works in the accented syllable of many 

 modern Latin adjectives ending in -inus, -ina, -inum, derived from Latin' words. As these 

 adjectives are derived from Latin roots and are regularly formed, their pronunciation should 

 properly follow classical analogies. When signifying, or referring to, time, material, or 

 inanimate substances, they should, therefore, according to Andrews & Stoddard's rule, have 

 the penult usually short, and the accent on the antepenult; as in gossipina, cannabina, secalina, 

 salicina, amygdalina, and other adjectives derived from plant names, like the classic nard- 

 inus, cyprinus, faginus. When these adjectives have other significations than those above 

 referred to, the penult under the ordinary Latin rule is usually long and accented ; as in 

 lupulina. leporina, hystricina, like the classic ursina, canina. 



The Use of Capital Letters. 



In accordance with the recommendations of the Nomenclature Commission of the 

 Botanical Club of the American Association for the Advancement of Science, specific or 

 varietal names derived from persons, or used as the genitive of generic names or as sub- 

 stantives, are printed with the initial capital letter. There is much difference of opinion 

 as to the desirability of this practice, many botanists, and almost all zoologists, following 

 the principle of writing all specific names with a small initial letter. Should this custom 

 prevail, much information concerning the history and significance of the specific names would 

 be lost. Thus in the Tulip-tree, Liriodendron Tulipifera, the specific name Tulipifera was 

 the ancient generic name; and the same with Lythrum Salicaria, L. Hyssopifolia, L. Vul- 

 neraria, and many other species. In all other forms of writing, personal adjectives such as 

 Nuttallii, Engelmanni or Torreyi are printed with capitals. We adhere to the ordinary 

 literary usage. 



Keys. 



A general Key of the Orders and Families has been prepared by Dr. Britton according 

 to the method followed in the Keys to the genera and species. This general Key has been 

 elaborated on the natural method, dividing the two subkingdoms of plants described in the 

 work into Classes, Subclasses, Orders and Families successively. The Orders are not 

 described in the work itself, but their principal distinguishing characters are given in this 

 key. The natural method adopted necessitates a considerable number of exceptions to 

 statements, owing to the varying degree of development of floral organs in the derivation 

 of plants from their ancestors ; these exceptions are either noted under the headings or indi- 

 cated by cross-references. 



In using this key, or any of the keys to genera or to species, the student will often find, 

 in the analysis of a plant that it does not provide all the information necessary for its deter- 

 mination; this is generally owing to the incomplete condition of the specimen collected; it 

 may be in flower, while the characteristic differences between it and others are only to be 

 found in the fruit, or vice versa; or the species may be dioecious, or polygamous, when its 

 other organs, perchance the characteristic ones, must be sought on another individual, and 

 there are various other causes for incompleteness. It is therefore earnestly recommended 

 that collections be carefully made, seeking to reduce as far as possible this more or less 

 necessary incompleteness. Where satisfactory material can not be obtained, it will usually be 

 found possible to reach the desired analysis by following out two or more lines of the key, 

 and by comparing the results reached with the descriptions to determine the family, genus 

 or species. The illustrations provide an almost indispensable aid in such cases. 



Assistance and Cooperation. 



In the preparation of both the first edition and of the second we have had valued 

 cooperation from many botanists, which is here gratefully acknowledged. The late Pro- 

 fessor Thomas C. Porter contributed much to the first edition by suggestion, specimens, 

 and the examination of proof sheets. Mr. Eugene P. Bicknell has contributed specimens 

 studied for both editions and read the proof sheets of the first. Dr. John K. Small has 

 assisted in the preparation of both editions, contributing the entire text of several families, 



