The term "indoor lily" encompasses several popular houseplants from different botanical families that share a common trait: their elegant, often trumpet-shaped flowers. While true lilies belong to the genus Lilium, many plants commonly called lilies, such as Peace and Calla Lilies, are not true lilies at all. This diversity leads to significant variations in their morphology, growth habits, and care requirements, making an understanding of their botanical backgrounds essential for successful indoor cultivation.
Peace Lilies are not true lilies but are members of the Araceae (Arum) family. Their botanical name, Spathiphyllum, refers to their unique flower structure. The showy white "flower" is actually a modified leaf called a spathe, which surrounds the central spike-like inflorescence, the spadix. This plant is prized for its glossy, dark green, lanceolate leaves that emerge directly from the soil in a clumping habit. Peace Lilies are known for their resilience and ability to thrive in low-light conditions, though they will bloom more profusely with bright, indirect light. They are also renowned for their air-purifying qualities, efficiently removing volatile organic compounds from the environment.
Calla Lilies, belonging to the genus Zantedeschia, are also part of the Araceae family. Like the Peace Lily, their stunning floral display is composed of a spathe and spadix. However, the Calla Lily's spathe is typically more flared and trumpet-shaped, available in a wide array of colors including white, yellow, pink, and deep purple. Their foliage is equally attractive, often being arrow or heart-shaped, and some varieties feature white speckles. Unlike the clumping Peace Lily, Calla Lilies grow from rhizomes. They prefer a period of dormancy after flowering, requiring less water. They demand bright, indirect light to perform their best indoors.
True lilies from the genus Lilium are often grown as temporary indoor plants. They grow from true bulbs, which are composed of fleshy scales. Their flowers are typically large, fragrant, and come in a vast range of colors and patterns. Asiatic hybrids are known for their upward-facing, brightly colored flowers and are generally easier to force into bloom indoors. Oriental hybrids, like the popular 'Stargazer', are famed for their intense fragrance and large, often outward-facing blooms. Both types require very bright light and cool temperatures to thrive and re-bloom indoors, making them more challenging as permanent houseplants compared to Peace or Calla Lilies.
From a botanical perspective, the differences are stark. Peace and Calla Lilies are aroids, adapted to lower light and consistent moisture, while true lilies are bulbous perennials requiring a dormancy period and high light levels. The flower morphology is a key differentiator: true lilies have true petals and sepals (tepals), whereas the showy part of Peace and Calla "flowers" is a spathe. Foliage also varies significantly, from the simple, lanceolate leaves of Peace Lilies to the speckled, sagittate leaves of some Calla Lilies and the whorled or scattered leaves on the stems of true lilies. Their root structures differ as well, with Peace Lilies having standard root systems, Calla Lilies spreading via rhizomes, and true lilies growing from bulbs.
