Lilium

The genus *Lilium* consists of herbaceous flowering plants that grow from bulbs.

These plants are famous for their large, often striking flowers. They hold a significant place in human culture and literature worldwide. Most species are native to the Northern Hemisphere. They typically thrive in temperate climates and extend into the subtropics. It is important to distinguish true lilies from other plants. Many unrelated plants use the name "lily" in their common titles. However, true lilies are highly toxic to cats.

Lilies are tall perennials that rely on underground organs for survival. They grow from bulbs, which are used for perennation, or surviving through different seasons. These bulbs can be naked or tunicless and scaly.

In some North American species, the bulb base develops into rhizomes. These rhizomes support numerous small bulbs. Some species also develop stolons to spread. Most bulbs remain buried deep in the soil. However, a few species form bulbs near the soil surface. Many species also produce stem-roots. These allow the bulb to grow naturally at a specific depth. Each year, the new stem produces adventitious roots above the bulb as it emerges. Additionally, many species have basal roots at the bulb's base. Some even produce contractile roots. These specialized roots physically move the bulbs deeper into the soil.

The flowers are often large and fragrant. They appear in colors such as white, yellow, orange, pink, red, and purple. Many display markings like spots or brush strokes. Flowers usually bloom in late spring or summer. They grow in clusters called racemes or umbels at the stem tip. Each flower features six tepals, which are segments that look like petals. These tepals may spread out or be reflexed. This creates shapes ranging from a funnel to a "Turk's cap." Each flower has a nectary at its base. The ovary is described as superior because it sits above the anther attachment point. The resulting fruit is a three-celled capsule.

The life cycles of lilies vary by climate. Most cool temperate species are deciduous. They remain dormant during the winter. However, species from areas with hot summers and mild winters follow a different pattern. This includes *Lilium candidum*, *Lilium catesbaei*, and *Lilium longiflorum*. These plants lose their leaves and enter dormancy in summer or autumn. They sprout between autumn and winter to form dwarf stems. These stems hold a basal rosette of leaves. The stems only begin to elongate once they receive sufficient chilling and warmer weather arrives. Seeds ripen in the late summer. Their germination patterns are often complex and adapted to cool climates.

Taxonomy, or the science of classification, is complex for this genus. There are 119 species currently counted. Scientists use different systems to organize them. Harold Comber provided a classical division in 1949. The genus is divided into seven main sections. These are Martagon, Pseudolirium, Liriotypus, Archelirion, Sinomartagon, Leucolirion, and Daurolirion. Different regions use different taxonomic authorities. For example, the *Flora of North America* is used for Section *Pseudolirium*. The *Flora of China* guides the taxonomy of Chinese species. Some groups, like *Sinomartagon* and *Leucolirion*, are divided into paraphyletic groups. This means the groups do not include all descendants of a common ancestor.

Lilies inhabit diverse environments across the globe. In the Old World, they range from Europe across Asia to Japan. They extend south to India and east to the Philippines. In the New World, they stretch from southern Canada through the United States. They commonly grow in woodland or grassland habitats. Some can survive in marshlands. Certain species in tropical southeast Asia are known as epiphytes.

In North America, deer populations pose a threat to wild lilies. Because large predators were eliminated, deer numbers have increased. They consume the plants, causing a downturn in wild populations. Gardeners often use fences as high as 8 feet to protect them.

Humans grow many lily species for ornamental purposes. They are popular in herbaceous borders and woodland plantings. Some species, such as *Lilium longiflorum*, are vital for the cut flower industry. These are often forced to bloom outside their normal season. For example, they are grown for the Easter trade. When grown this way, they are called Easter lilies. When planting, gardeners usually use bulbs during the dormant season. They prefer sun or partial shade with well-draining, loamy soil. Most species bloom during July or August in the northern hemisphere.