The Calla Lily: Structure, Growth, and Cultivation

Overview

The plant commonly known as the calla lily (Zantedeschia aethiopica) is not a true lily despite its name. Many plants are casually called “lilies,” but only members of the Liliaceae family are considered genuine lilies. The calla lily actually belongs to the arum family (Araceae), which also includes plants like jack-in-the-pulpit.

Unlike true lilies, which typically have six distinct petals, the calla lily features a single, smooth, white structure that looks like a petal. This structure, known as a spathe, curls backward to expose a yellow central spike called a spadix. The spadix contains numerous tiny, true flowers.

Native to wet, marsh-like habitats in South Africa, the calla lily may not be a “real” lily, but its elegant, trumpet-shaped white blooms make it highly admired.

Characteristics

If you examine a cluster of calla lilies, you will notice large, arrowhead-shaped leaves growing on long stalks, but no visible above-ground stem. This is because the plant develops from a rhizome, a thick, underground stem. From this fleshy structure, the leaves, roots, and bracts emerge directly.

The plant’s signature white, funnel-shaped structures are actually modified leaves called spathes. Each spathe surrounds and protects a single upright spadix, about 3 inches (7.6 cm) long, which is densely covered with tiny flowers.

The arrangement of these flowers is specialized: male flowers occupy the upper portion of the spadix and produce abundant pollen, while female flowers are located toward the lower section.

Cultivation

Calla lilies are widely grown in gardens, pots, and floral arrangements. They typically form clumps that can reach about 3 feet (roughly 1 meter) in height and spread up to 2 feet (about 60 cm) wide.

They thrive in moist, fertile soil and can grow well in either full sun or partial shade. These plants are especially suitable for water gardens, pond edges, or areas that remain consistently damp, as they can even tolerate shallow standing water.

Although they are herbaceous perennials, calla lilies will go dormant when exposed to cold temperatures or dry conditions. In regions where winter temperatures drop below about 20°F (-6.7°C), the plants should be lifted and brought indoors until warmer weather returns.

Propagation is easy: the rhizomes can be divided to produce new plants. In addition to the classic white form, there are many cultivars and related species with spathes in colors such as green, yellow, pink, and deep maroon.