Lilies are usually erect leafy stemmed herbs. The majority of species form naked or tunic-less scaly underground bulbs from which they overwinter.

Lilies are usually erect leafy stemmed herbs. The majority of species form naked or tunic-less scaly underground bulbs from which they overwinter. In some North American species the base of the bulb develops into rhizomes, on which numerous small bulbs are found. Some species develop stolons. A few species form bulbs at or near the soil surface .