16 INTRODUCTION 



have been assigned variously in accordance with the groups of fungi con- 

 cerned. Thus for the Mycetozoa and Lichens the date remains 1753; for 

 the Uredinales, Ustilaginales, and Gasteromycetes it is 1801, based on 

 Persoon's "Synopsis Methodica Fungorum"; and for all other fungi 

 1821-1832, based on the appearance of the various volumes of Fries' 

 "Systema Mycologicum." So the beginning date for the Hymenomycetes 

 is based upon Volume I of this work, part of which is said to have appeared 

 late in 1820 and the remainder in 1821. Any names given by later authors 

 are valid only if the species concerned were not included in that volume. 

 The first section of Volume II appeared in 1822 and included, and there- 

 fore is authoritative for their nomenclature, the Discomycetes and many 

 of the larger Heterobasidiae, and the sclerotioid Fungi Imperfecti. Part II 

 of this volume appeared in 1823 and contained some of the Gastero- 

 mycetes, whose basic date is Persoon's work in 1801, and the Pyreno- 

 mycetes (and Sphaeropsidales). Volume III, Section I (1829) contains 

 (in addition to the remainder of the Gasteromycetes and the Mycetozoa) 

 the Erysiphales. For this last group it is the basic work. Section II (1832) 

 consists mainly of the Fungi Imperfecti, but also Hypodermii (i.e., 

 Uredinales and Ustilaginales) for which the work of Persoon is basic. 



A generic name is always a noun in the singular number. It is always 

 written with an initial capital. The specific epithet is mostly an adjective 

 in Latin form, which must agree in gender with the generic name (e.g., 

 Lepiota procera), or it may be the genitive case of some noun (e.g., 

 Mycosphaerella fragariae), or it may be a noun in the nominative case 

 (e.g., Xylaria hypoxylon or Fomes pinicola). Mostly the specific epithet is 

 written without an initial capital, except where it is a noun in the nomi- 

 native case that was an old generic name, or where it is based upon a 

 personal name or a generic name. INIany authors prefer to decapitalize 

 all specific epithets, even when based upon personal or generic names. 

 The author attempts to follow this procedure in this book except where 

 quoting directly from another author. 



Valid publication of a hitherto undescribed plant consists of the 

 assignment of a name and the description of the organism, in proper 

 manner. After 1935 all descriptions to be valid must be in Latin aside 

 from any descriptive text in any other language. The description of a 

 species must be based upon a definite collection, specimen, or culture, 

 which is designated as the "type specimen." This should be preserved 

 and the place where it is deposited should be indicated. A genus must be 

 based upon some particular species, the "type species." A family must 

 be based upon a "type genus" and an order upon a "type family." 

 Ordinarily the familial and ordinal names are based upon the stem of the 

 name of the type genus, with the appropriate endings, -aceae or -ales, 

 respectively. If a genus, family, or order is divided into two or more parts 



