color designations could ever be constructed 
that distinguish all named clones. 
The dates of cultivation or introduction are 
important in establishing the priority of a 
cultivar name used for validation. (The terms 
“cultivated” and “introduced” are synonymous.) 
The dates of publication of valid cultivar names 
are accepted when there is evidence of dissemi- 
nation of asexual propagations and subsequent 
cultivation in botanic gardens, arboretums, or 
private gardens. The acceptance of valid names 
is based on the International Code of Nomencla- 
ture for Cultivated Plants—1980 and does not 
imply any judgment regarding a cultivar’s 
horticultural superiority or distinctness. 
Supplemental and often diagnostic data are 
included here to amplify the original descrip- 
tions and have no relevance to the validation of 
names. Although many of the references to the 
cultivars consist of commercial sources, this 
list is not a buyers’ guide. No responsibility can 
be accepted for current availability of plants 
from the sources mentioned. 
A few cultivars of commercial importance are 
listed as invalid. Some of these names could be 
validated by publication of a description; others 
would require a published change of name by 
or with the permission of the originator. 
A list such as this can hardly be compiled 
without some errors and misinterpretations. 
Information that will clarify the identity of any 
of the plants will be gratefully received. 
Format 
The checklist presents information in the 
format described next. 
e Cultivar names are listed in alphabetical 
order. 
e The earliest published reference for a 
name is shown in parentheses, followed by 
the published description or by the nota- 
tion “without description” if the source 
contained no description. A second refer- 
ence, with description, is included when 
available. Subsequent references provide 
additional pertinent data. 
Important information from the original 
source follows the name and is introduced 
by acolon. Descriptive information is 
presented in the following order: habit, 
leaf characters, flower characters, fruit 
characters, and miscellaneous data such 
as hardiness and disease resistance. 
Information from sources other than the 
original one is also introduced by a colon. 
When available, the source, discoverer, 
selector, namer, and introducer, with 
significant dates, follow. Undocumented 
information is set off by periods. 
Taxa categories are differentiated by the 
following typefaces: 
‘Alba’ valid cultivar name 
‘Aurea’ invalid cultivar name 
angustifolia valid species name 
chinensis invalid species name. 
When synonyms are listed, they are 
presented under each entry and are 
preceded by an equal sign (=). The legiti- 
mate name, if there is one, appears first 
and in bold face, and then illegitimate 
synonyms follow in alphabetical order. 
Dubious, suspect, and unconfirmed 
synonyms are preceded by a question 
mark. 
Common misspellings and alternate 
listings of cultivar names are listed when 
known. 
The species identity, when determined for 
a cultivar, appears in italics. 
Color designations are included when 
available. They are differentiated by RHS 
for the RHS Colour Chart (Royal Horticul- 
tural Society 1966) or HCC for the Horti- 
cultural Colour Chart (British Colour 
Council in collaboration with the Royal 
Horticultural Society 1942). 
