International Code, as what are termed nomina conservanda, of
generic names commonly used but later in date of publication
than other, relatively unfamiliar names. Thus, the water-hya-
cinth is correctly known in the genus Eichhornia, a name not
published until 1842, rather than in the genus Piaropus, which
dates from 1837. Similarly, the zephyr-lilies belong in the genus
Zephyranthes, an 1821 name, rather than in Atamosco, pub-
lished in 1763.
 Common Names
 Very often the precision of understanding that is the central
purpose of the use of scientific names is met, at least on a local
basis, equally well by a well-selected and narrowly applied com-
mon name. Many plants have such common names, and when-
ever they are known to the writer, these names have been in-
cluded in the present Checklist.
 A degree of editorial license has been applied to the selec-
tion of a "best" common name, where more than one is applied
to the same plant, or where the same common name is used
for two or more different plants. In a number of instances,
in a dilemma familiar to all writers of floristic treatments,
a widely used but scarcely printable common name has been
rejected for an innocuous synonym. Whenever two or more
common names for a plant are believed to be in widespread
use, and of equal suitability, this Checklist uses the name
that has been selected in two of the more comprehensive efforts
to establish uniformity in the application of common names.3
Since the names of these standardized lists are drawn, at least
in part, from the same sources as the names in this Checklist,
a large proportion of these common names will be found to
be identical.
 The concept is rejected, however, that there can be a single
"standardized" common name for a plant, for common names,
by the very meaning of the phrase, are of "common" origin
and are not established by the application of uniform rules
or by consistent usage in scientific publications. Naturally,
true common names often lack precision as to what plants
are referred to, but this is a function better left to the uni-
versally applicable scientific name and, in any event, is not
achieved by the standardization of common names within a

 SKelsey, H. P., & W. A. Dayton (editors). 1942. Standardized plant
 names. 2nd ed. McFarland Co., Harrisburg, Pa. 675 p.
 Darrow, R. A. (chairman). 1966. Subcommittee on standardization
 of common and botanical names of weeds. Weeds 14: 347-386.