A true lily is a flowering plant belonging to the genus Lilium. The common name “lily” is often broadly applied to many plants that share a similar flower shape, causing confusion. True lilies are distinguished by their large, prominent flowers and grow from an underground storage organ called a bulb. This group is native primarily to the temperate regions of the Northern Hemisphere, known for their dramatic height and varied summer blooms.
Defining the True Lily
True lilies are classified within the family Liliaceae, defined by their placement in the genus Lilium. All plants in this classification are herbaceous perennials, meaning the foliage dies back annually while the underground bulb survives to regrow. The bulb functions as the plant’s storage organ.
The bulb of a Lilium species is scaly and naked, lacking the papery outer protective layer, or tunic, found on other common bulbs like tulips or daffodils. These fleshy scales are modified leaves that store the starches and nutrients necessary for the plant’s survival. This structure is one of the most reliable characteristics separating a true lily from other similar-looking species.
Distinct Physical Features
A true lily plant has a tall, usually unbranched stem that can range from one to eight feet in height. Leaves typically grow in a whorled or spiraled arrangement along the stem. The flowers are the most recognizable feature, often large and borne in clusters at the stem’s tip.
The floral structure consists of six identical petal-like segments known as tepals, arranged in two whorls of three. Inside the flower, there are typically six prominent stamens, which bear pollen. Lily flowers exhibit three primary shapes: the funnel or trumpet, the open bowl or cup, and the fully recurved petals of the Turk’s cap style.
Common Lily Varieties
Horticulturists categorize Lilium hybrids into divisions based on parentage, with three groups being most common:
- Asiatic Hybrids: These are the earliest to bloom, typically in early summer, and are the shortest garden lilies. They feature a wide spectrum of colors, are often unscented, and have upward-facing flowers.
- Oriental Hybrids: Prized for their large, showy blooms and intense, sweet fragrance, they flower later in mid-to-late summer. These varieties are taller and exhibit colors in the pink, red, and white range, often with speckled patterns.
- Trumpet Hybrids: Including Aurelian types, these are characterized by deeply elongated, trumpet-shaped flowers and strong fragrance. They are among the tallest varieties and provide summer color after the Asiatic types have finished blooming.
Clarifying Common Misnomers
Many plants named “lily” are not true members of the genus Lilium, belonging instead to different plant families. The Calla Lily (Zantedeschia) grows from rhizomes, not scaly bulbs. Similarly, the Day Lily (Hemerocallis) is a separate genus whose flowers only last for a single day, unlike the longer-lasting blooms of Lilium.
Another misnomer is the Water Lily (Nymphaea), which grows in aquatic environments from tubers. Lily of the Valley (Convallaria) is a separate perennial herb with small, bell-shaped flowers that also lacks the defining scaly bulb. The use of “lily” in these common names is based purely on a superficial resemblance to the flower shape rather than any botanical relationship.