Georgia Wildlife Federation

Resources < Wildlife Habitats < Guide to Native Plants of Georgia for Wildlife < Thalia dealbata

Powdery Alligator-Flag is very similar to Golden Canna in purpose, usage, and contribution to wildlife. Powdery Alligator-Flag, however, has a larger natural range up into zone 6 and therefore may be safely planted without need for digging the rhizomes. It also has a unique appearance, because Canna hybrids are fairly common in modern landscapes. It is a marginal aquatic plant that adds height without becoming as invasive as other marginal aquatics like cattails. In addition, it has much more attractive flowers.

Powdery Alligator-Flag adds a noticeable tropical touch to landscapes, ponds, swamps, and other wet places. Unlike Golden Canna, Powdery Alligator-Flag requires wetter, non-terrestrial conditions—plant in locations inundated with at least 4 inches of water, and up to as much as 2 feet. Great companion plants include other marginal aquatics like Golden Canna, Arrowhead, Juncus, Lizard’s Tail, Swamp Sunflower, Green Arrow Arum, Goldenclub, and Pickerelweed and native waterlilies (provided waters are still and there exists at least 2 feet of water to plant them in). Terrestrial companions include cold-hardy palms like Sabal species (S. minor and S. palmetto), saw palmetto, and needle palm.

Family: Marantaceae (Prayer-Plant, Arrowroot)

Description: Thick ovate to lancelolate blue green leaves dusted with white powder; edged in purple Small violet flowers on 8 inch panicle carried high above the foliage Hardy water canna (or powdery thalia) is a rhizomatous marsh or marginal aquatic perennial that features long-stalked canna-like foliage and violet blue flowers. It is a tall plant (to 6-10’) that lends a tropical flavor to ponds and water gardens. It is native to swamps and ponds from South Carolina to Florida west to Missouri and Texas. It is rare to Missouri, its distribution being limited to swampy areas in the southeastern lowlands region. Thalia features paddle-shaped to lanceolate-elliptic blue-green canna-like leaves (to 18” long) on petioles to 24” long. Foliage is dusted with white powder. Violet flowers appear in branched open panicles (to 8” long) atop scapes typically rising well above the foliage to 6’ (less frequently to 10’) tall. Blooms July and August. Genus name honors 16th century German physician and naturalist Johann Thal.

Size: 6-8 feet tall and 3-4 foot wide (per stem)

Habit: Upright, herbaceous perennial marginal aquatic plant

Growth Rate: Fast to moderate

Light: Full sun preferred, but tolerant of partial shade

Planting and Care: Unlike Golden Canna, Powdery Alligator-Flag requires wetter, non-terrestrial conditions—plant in locations inundated with at least 4 inches of water, and up to as much as 2 feet. Large undrained tubs (5-20 gallons) may also be used as containers. Plants require fertile and organically rich soils.

Ornamental Value: Assets include the tropical-looking foliage, Powdery Alligator-Flag’s height compared to many marginal aquatics, and of course its elaborate flowers which superficially resemble those of irises. It is also markedly less aggressive than other marginal aquatics like cattails.

Landscape Use: Powdery Alligator-Flag is useful for moist areas. These include near gutters, ponds, lakes, streams, creeks, or in artificial water gardens. Irrigation can maintain the plant through dry spells if a dry location for the plant is preferred. It is most useful in masses or clumps.

Wildlife Benefits: Powdery Alligator-Flag provides a great deal of protection to fish, amphibians, insects, and other aquatic life. It shades and cools water also, and minimizes heating that can kill fish and lower the dissolved oxygen in smaller ponds. The foliage allows the larvae of dragonflies to have a save place to climb from ponds and metamorphose into adults. The foliage is host to the larvae of the Brazilian Skipper butterfly, while nectariferous insects feed on the pollen and nectar of its flowers.

Native Habitat: Native to wetlands across the southeastern Atlantic Coastal Plain and Mississippi River floodplains. It ranges from South Carolina west to Texas and northeast to Missouri, Illinois, and Kentucky. Favored habitats include swamps, bogs, the margins of lakes, ponds, slow-moving rivers or streams, and wet bottomlands.