Lilium (members of which are the true lilies) 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 but they may be unrelated to true lilies.
The range of lilies in the Old World extends across much of Europe, across most of Asia to Japan, south to the Nilgiri mountains in India, to Indochina and to the Philippines. In the New World they extend from southern Canada through much of the United States. They are commonly adapted to either woodland habitats, often montane, or sometimes to grassland habitats. A few can survive in marshland and epiphytes are known in tropical southeast Asia. In general they prefer moderately acidic or lime-free soils.
Lilium longiflorum flower – 1. Stigma, 2. Style, 3. Stamens, 4. Filament, 5. Tepal
Lilies are tall, leafy stemmed herbs generally ranging in height from 2–6 ft (60–180 cm). 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.
The flowers are large, 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. Flowers are borne in a raceme or umbel at the tip of the stem, with six tepals spreading or reflexed, to give flowers varying from funnel shape to a Turk's-cap. The tepals are free from each other, and bear a nectary at the base of each flower. The ovary is 'superior', borne above the point of attachment of the anthers. The fruit is a three celled-capsule.
Seeds ripen in late summer. They exhibit varying and sometimes complex germination patterns, many adapted to cool temperate climates.
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.
Taxonomical division in sections follows the classical division of Comber, species acceptance follows World Checklist of Liliaceae, the taxonomy of section Pseudolirium is from the Flora of North America, the taxonomy of Section Liriotypus is given in consideration of Resetnik et al. 2007, the taxonomy of Chinese species (various sections) follows the Flora of China  and the taxonomy of Section Archelirion follows Nishikawa et al. as does the taxonomy of Section Archelirion.
Some species formerly included within this genus have now been placed in other genera. These genera include Cardiocrinum, Notholirion, Nomocharis and Fritillaria.
Many species are widely grown in the garden in temperate and sub-tropical regions. Sometimes they may also be grown as potted plants. A large number of ornamental hybrids have been developed. They can be used in herbaceous borders, woodland and shrub plantings, and as patio plants. Some lilies, especially Lilium longiflorum form important cut flower crops. These may be forced for particular markets; for instance, L. longiflorum for the Easter trade, when it may be called the Easter lily.
Lilium bulbs are starchy and edible as root vegetables, although bulbs of some species may be very bitter. The non-bitter bulbs of L. lancifolium, L. pumilum, and especially L. brownii (Chinese: ?? ?; pinyin: baihé gan) and Lilium davidii var unicolor cotton are grown on a large scale in China as a luxury or health food, and are most often sold in dry form. They are eaten especially in the summer, for their perceived ability to reduce internal heat. They may be reconstituted and stir-fried, grated and used to thicken soup, or processed to extract starch. Their texture and taste draw comparisons with the potato, although the individual bulb scales are much smaller. Yuri-ne (lily-root) is also common in Japanese cuisine, especially as an ingredient of chawan-mushi (savoury egg custard).
The "lily" flower buds known as jinzhen (??, "golden needles") in Chinese cuisine are actually from the daylily Hemerocallis fulva.
Lilies are used as food plants by the larvae of some Lepidoptera species including the Dun-bar.
Pests and diseases
Aphids may infest plants. Leatherjackets feed on the roots. Larvae of the Scarlet lily beetle can cause serious damage to the stems and leaves. Plants can suffer from damage caused by mice, deer and squirrels. Slugs, snails and millipedes attack seedlings, leaves and flowers. Brown spots on damp leaves may signal botrytis (also known as lily disease). Various fungal and viral diseases can cause mottling of leaves and stunting of growth.
Lilies are usually planted as bulbs in the dormant season. They are best planted in a south-facing, slightly sloping aspect, in sun or part shade, at a depth 2½ times the height of the bulb (except L. candidum which should be planted at the surface). Lilies have contractile roots which pull the plant down to the correct depth, therefore it is better to plant them too shallowly than too deep. A soil pH of around 6.5 is generally safe. The soil should be well-drained, and plants must be kept watered during the growing season. Some plants have strong wiry stems, but those with heavy flower heads may need staking.
The botanic name Lilium is the Latin form and is a Linnaean name. The Latin name is derived from the Greek ?e?????, leírion, generally assumed to refer to true, white lilies as exemplified by the Madonna lily. The word was borrowed from Coptic (dial. Fayyumic) hleri, from standard hreri, from Demotic hrry, from Egyptian hr?t "flower". Meillet maintains that both the Egyptian and the Greek word are possible loans from an extinct, substratum language of the Eastern Mediterranean. The Greeks also used the word ??????, krinon, albeit for non-white lilies.
The term "lily" has in the past been applied to numerous different flowering plants, often with only superficial resemblance to the true lily, including lotus, ranunculus, tulip, iris, anemone, agapanthus, zantedeschia, daylily, and others. All English translations of the bible render the Hebrew shushan, shoshan, shoshanna as "lily". For instance, the "lily among the thorns" of Song of Solomon may be the honeysuckle.
Many varieties of lily are extremely toxic to cats, causing acute renal failure even in small amounts. This is particularly true in the case of Easter lily plants, though other Lilium and the related Hemerocallis can also cause the same symptoms.