hardiness, and on other important characteristics of these selections have 
been considered in deciding on introductions and in formulating the 
descriptions here presented. 
In connection with the research on the genus Hemerocallis at the 
New York Botanical Garden, which began in 1912, a total of about 70,000 
pedigreed seedlings have been grown. Some 500 of these have been 
selected for future breeding and for critical evaluation in respect to their 
value for cultivation in gardens. Beginning in 1930 and previous to the 
present publication, 28 different new horticultural clones and one species 
(Hemerocallis multiflora) have been distributed to the trade. The present 
list of introductions adds several rather distinctly new types. In at least 
one rather important horticultural feature, each of these clones is different 
from any other introduction. 
In the daylilies, selective breeding following hybridization has been 
especially effective in developing distinctly new clones in which certain 
characters are much modified or even new in expression. 
As a rule, in Hemerocallis in the first generation hybrids of species 
crosses there is some degree of dominance and recessiveness or there is an 
intermediate expression for each pair of the contrasted characters of the 
parents. But differences in the behavior of several different contrasted 
characters are responsible for hybrids that are quite distinct from either of 
the parents. This condition becomes more complex when there are 
multiple-hybrid differences and especially when three or more species 
are involved in an ancestry. 
But in these daylilies there are numerous cases of rather distinctly new 
expressions or modifications of character, and of these several classes 
are to be recognized :— 
1. The modification may be an expression that is intermediate for the contrasted 
characters of the two parents. When this involves the interaction of a particular 
pair of hereditary units (alleles) in heterozygous condition the next generation shows 
simple segregations and the new character “does not breed true.” 
2. Many cases of differences are due to developmental interferences in expres- 
sion. For example, the “twisted petal” character appears somewhat different with a 
narrow petal than with a broad petal. 
3. In more complicated cases the hereditary factors carried by two or more non- 
homologous chromosomes are involved in complementary and modifying reactions. 
Selective breeding after hybridization is especially effective in such cases. It provides 
for increased complexity in the complement of chromosomes; it develops greater 
homozygocity when this increases the intensity of expression; it accumulates 
hereditary genes that have mutated; and it continues new associations of genes that 
may result from cross-overs or other rearrangements within chromosomes, 
An example of this is the intensification of red pigments which gave the first plants 
with flowers that are dark mahogany-red. First there were hybridizations which in- 
volved yellow-flowered species and species that had fulvous flowers. The F; generation 
had pale fulvous flowers and none of the F: that were obtained had flowers that 
were darker than the more fulvous plant. Then plants that showed the greatest 
degrees of anthocyanin pigmentation were used as parents in further breeding and 
back-crossing. In the fifth generation seedlings were obtained whose flowers had 
degrees of dark red pigmentation not seen hitherto in any daylily. The various 
complementary factors which interact in these daylilies to intensify anthocyanin 
