When the seedlings flower, the flowers are studied, and the best plants are selected. These are crossed again and again. Each time, the hybridizer must wait patiently to select the best progeny from the cross. Through hybridization, the limited gene pool of Hemerocallis species has been broken up and recombined, resulting in offspring with features not found in any species and giving modern hybrid daylilies a completely new look. Hybridization can change the genetic makeup of plants in many ways.
Tetraploid plants have double the number of chromosomes and tend to be larger and more vigorous.
Along Daylily Walk , green labels indicate tetraploid plants and brown labels indicate plants with the normal number of chromosomes. Daylily Walk features more than 400 of the best modern hybrid daylilies, demonstrating the wide range of flower color, shape, and pattern that is the result of the hybridizer's art. All daylily labels include the genus, Hemerocallis , and the cultivar name of the plant, which is always enclosed in single quotation marks. The name on the bottom of the label is the name of the hybridizer who registered the cultivar. The American Hemerocallis Society is the registration authority for all daylily cultivars.