EXPLANATIONS 



XV 



In generic names, the system of Bentham and 

 Hooker (Genera Plantarum) has been followed. 

 This system makes fewer changes in accepted 

 horticultural names than any other, and this i-s 

 considered to be a distinct merit. The chief rea- 

 son for adopting the British ideas of genera, how- 

 ever, is that Index Kewensis affords a complete 

 finding-list of species under those genera. It 

 would be impossible, in a work like the present, 

 to follow the more recent system of Engler and 

 Prantl (Die Natiirlichen Pflanzenf amilien ) , be- 

 cause there is no index or finding-list for the 

 species under those genera, and to make the 

 proper combinations of generic and specific names 

 for horticultural plants would necessitate a compi- 

 lation practically equivalent to Index Kewensis. 

 However, the various contributors have been at 

 liberty to adopt their own ideas of generic limita- 

 tions, so that the work will be found to occupy a 

 somewhat middle ground between the British and 

 German ideas of genera. 



CHIEF LITERABT AIDS. 



In the compilation of this work, the Editor has 

 had access to most of the important world-floras, 

 and to the leading geographical floras. In the 

 systematic botany, the greatest help has been 

 derived from the following great general works : 

 Bentham and Hooker, Genera Plantarum (1862- 

 1883); Hooker & Jackson, Index Kewensis (1893- 

 1895); DeCandoUe's Prodromus (1824-1873)- 

 DeCandolle's Monographiss Phanerogamarum 

 (1878-1896, and continuing); Engler and Prantl, 

 Die Natiirlichen Pflanzenfamilien (begun 1889) ; 

 Botanical Magazine (1786 to the present, and con- 

 tinuing); Botanical Register (1815-1847); Eevue 

 Horticole, Paris (1829 to the present, and continu- 

 ing) ; Gardeners' Chronicle, London (1841, and con- 

 tinuing) ; Garden, London (1871, and continuing) ; 

 Loddiges's Botanical Cabinet, London (1817-1833) ; 

 Flore des Serres, Ghent (1845-1880); L'Ulustration 

 Horticole, Ghent (1854-1896) ; Gartenflora, Berlin 

 (1852, and continuing) ; Garden and Forest, New 

 York (1888-1897); Nicholson's Illustrated Diction- 

 ary of Gardening, London (1884-1887) ; Mottet's 

 translation of Nicholson, Paris (1892-1899) ; Siebert 

 and Voss, Vilmorin's Blumengartneri (1896). 



ROW TO TJSE THE KEYS 



In order to facilitate the study of the plants, the 

 species have been arranged systematically, under 

 the genus, rather than alphabetically. However, 

 in all genera which contain 15 or more species, an 

 alphabetical index has been supplied for purposes 

 of rapid reference. The grouping of the species 

 is founded preferably on horticultural rather 



than on botanical characters, so that the ar- 

 rangement does not always express botanical re- 

 lationships. The grouping and the keys are 

 arranged primarily to aid the gardener in making 

 determinations of species. Every effort is made 

 sharply to contrast the species rather than to de- 

 scribe them. A word of explanation will facilitate 

 the use of the keys. The species are arranged in 

 coordinate groups of various ranks, and groups of 

 equal rank are marked by the same letter. Thus, 

 group A is coordinate with aa and with AAA, and 

 B with BB and bbb. Moreover, whenever possible, 

 the coordinate keys begin with the same catch- 

 word : thus, if A begins "flowers,"' so do AA and 

 AAA ; and this catchword is not used for keys of 

 other rank. As an example, refer to Acer, page 

 12. Look first at a, beginning "foliage;" then at 

 AA (p. 15), also beginning "foliage." Under a 

 are the coordinate divisions B and BB, each with 

 "bloom" for the catchword. Under B there are 

 no subdivisions, but under BB there are divisions 

 0, CO and ccc, each with "fls." for a catchword. 

 Under o there are no subdivisions, but cc has 

 four coordinate divisions, D, DD, ddd, dddd, each 

 with "Ivs." for a catchword, and so on. In other 

 words, if the plant in hand does not fall under A, 

 the inquirer goes at once to aa. If it falls under 

 A, then he determines whether it belongs to B or 

 to BB, and so on. 



A diagrammatic display of a scheme would 

 stand as follows: 



A. Leaves, etc. 



B. Flowers, etc. 



c. Fruits, etc. 

 c. Fruits, etc. 

 BB. Flowers, etc. 

 AA. Leaves, etc. 



B. Roots, etc. 



c. Flowers, etc. 



D. Margins of leaves, etc. 

 DD. Margins of leaves, etc. 

 C. Flowers, etc. 

 BB. Roots, etc. 

 BBB. Roots, etc. 

 AAA. Leaves, etc. 



PBONUNCIATION 



Accent marks are used to aid the reader in pro- 

 nouncing the name. The accent designates (1) 

 stress, or the emphatic syllable, and (2) the length 

 of the emphatic vowel. Following the American 

 custom, as established by Gray and others, a grave 

 accent ( ^ ) is employed to designate a long vowel, 

 and an acute accent (/ ) a short vowel. Thus, 

 officinale is pronounced o&ci-nay-li ; mici'ocdrpus 

 is pronounced microoarp'-us. Ordinarily in diph- 

 thongs the mark is placed over the second letter. 

 Thus, in aiirea the au is meant to have its custo- 

 mary long sound, as if written mce. Double vow- 

 els take their customary English sounds, as ee and 



