Day lily : A genus of plants (Hemerocallis) closely resembling true lilies, but having tuberous rootstocks instead of bulbs. The common species have long narrow leaves and either yellow or tawny-orange flowers.

Day lily : A genus of plants (Funkia) differing from the last in having ovate veiny leaves, and large white or blue flowers.

Example:


Taxonomy
daylily, Daylilies, flower, species, cultivars, hort, plants, Hemerocallis fulva, Hemerocallis, Nakai, hybrids, Tawny Daylily, stem, hybridizers, Traub, free encyclopedia, the roots, petals.

Defination from the web:
... It is called Roadside or Railroad Daylily, and gained the nickname Wash-house or Outhouse Lily because it was frequently planted at such buildings. ...