Lilium is a genus of herbaceous flowering plants growing from bulbs, all with large, prominent flowers. They comprise a genus of about 110 species in the lily family Liliaceae. Most species are native to the temperate northern hemisphere, though their range extends into the northern subtropics.
Lilies form an important group of flowering garden plants and are important in culture and literature in much of the world. A few species are sometimes grown or harvested for the edible bulbs.
The species in genus Lilium are true lilies. Many other plants have "lily" in their common names, some of which are quite unrelated to true lilies.
Lilies are leafy stemmed herbs. They form naked or tunic-less scaly underground bulbs which are their overwintering organs. In some North American species the base of the bulb develops into rhizomes, on which numerous small bulbs are found. Some species develop stolons. Most bulbs are deeply buried, but a few species form bulbs near the soil surface. Many species form stem-roots. With these, the bulb grows naturally at some depth in the soil, and each year the new stem puts out adventitious roots above the bulb as it emerges from the soil. These roots are in addition to the basal roots that develop at the base of the bulb.
Most cool temperate species are dormant in winter. Most species are deciduous, but a few species (Lilium candidum, Lilium catesbaei) bear a basal rosette of leaves during dormancy.
The large flowers have six tepals. They are often fragrant, and come in a range of colours ranging through whites, yellows, oranges, pinks, reds and purples. Markings include spots and brush strokes. The plants are late spring or summer flowering.
Seeds ripen in late summer. They exhibit varying and sometimes complex germination patterns, many adapted to cool temperate climates.