I found this dscription at LoonSong :
"The crown, located between the roots and the foliage, is the heart of the daylily, functioning as its essential growth center. Most daylilies must have a piece of the crown (along with some roots and foliage) to grow; a daylily does not naturally grow from a piece of true root or from a leaf cutting. Daylilies do not grow from bulbs. Some daylilies (typically species or “wild” types) form rhizomes that can produce a new plant. Rhizomes have scales and internodes, while true roots do not. Most modern cultivars do not form rhizomes.
Roots vary in shape and thickness, and they generally grow more downward than out. Enlarged or thickened parts of the roots are thought to be for water storage.
A daylily's strap-like leaves emerge directly from the crown and grow in an arching or fountain-shape clump. (This is one way to distinguish a daylily from a “true” lily, i.e., Lilium, which has whorls of stemmed foliage at intervals on a stalk.)
Scapes (flowering stems), initiate from the crown and form branches and buds for flowering. Scape heights range from 12" to 60" or taller.
Modern daylilies do not grow true from seed. The offspring from seeds will usually look quite different from either of the parent plants.
To be true to name, a daylily needs to be grown from a piece of the original plant. The usual process is to dig a mature plant and make divisions. To be viable, a division must include part of the crown, part of the root system, and part of the upper foliage. (Note that a piece of rhizome may also produce a new daylily plant for those types that produce rhizomes)."
Maybe both rhizome and stolon are both names for the same thing? The bulby - thingys at the end of the roots are called "tubers" in one drawing I found.
