The humble daylily, once limited to a few varieties of hybrid cultivars, now blooms in more colors and forms than could have been imagined by early hobbyists.
Spiders must have sepals and petals that grow in a length to width ratio of at least 5 to 1. Modern breeders aim for large flowers with longer, narrower segments.
Older diploid spider flowers measured from 2 to 4 inches across. Modern diploid Pink Super Spider has 10-inch flowers. Tetraploid Royal Celebration’s blooms spread 12 inches across.
Most spiders have three inner petals and three outer sepals, collectively called segments. Petit and Peat list five descriptively named shapes for daylily segments; pinched, twisted, quilled, spatulate and cascading.
Early spiders were diploids — they had a set of chromosomes from each parent. Recent emphasis is on developing tetraploids — plants which have four sets of chromosomes that allow wider variety. Diploids and tetraploids cannot cross-fertilize.
Daylilies whose flower segments have a ratio of greater than 4 to 1 but less than the requisite 5 to 1 are called "spider variants." Flowers with smaller ratios but unusual segment forms are just "unusuals."