This week for Flora and Fauna Friday we’re on the lookout for a rare, coastal plain endemic, backwater wildflower, Powdery Alligator-Flag (Thalia dealbata).
Powdery Alligator-Flag is one of just two species in its genus found in the United States. That genus, Thalia, is our only representative for the Arrowroot family, Marantaceae. Powdery Alligator Flag is a bona fide rare plant here in South Carolina, with only a smattering of population sites in our coastal counties. Edisto Island is notable in being a population stronghold for this rare plant.
Powdery Alligator-Flag can be found in practically all of our natural freshwater backwater wetlands around Edisto Island. It will most readily inhabit shady marshes and shallow swamps around the Island. It is even mildly salt tolerant, and can handle a touch of saltwater intrusion. Powdery Alligator-Flag is an emergent aquatic plant, growing in mucky soil in a foot or so of water along the water’s edge. It spreads laterally through rhizomes into large clumps, or along an entire shoreline in good conditions. Its foliage can reach three to five feet in height with large elliptical leaves a foot long and half as wide. It’s a perennial plant and can even be evergreen through a mild winter. All and all, it looks a lot like a taller, bulkier Canna Lily. However, the most recognizable feature of this plant is not its prominent foliage but its handsome flowers. In about June, Powdery Alligator-Flag gets into full bloom sending up thin flower stalks five to eight feet high. These are capped with a cluster of powdery platinum-white flower buds that eventually bear delicate deep-violet petals. The plant will continue to bloom until fall and the flowers will mature into a spherical nut-like fruit. These nuts are mostly hollow and float, allowing the singular seed within to journey across the water. Despite its rarity and specialized life history, Powdery Alligator-Flag is actually a very hardy plant and a perfect native addition to any wetland garden, pond edge, or detention basin. Powdery Alligator-Flag tolerates full sun, partial shade, mucky soils, fluctuating water levels, freezing, and even a dash of salt. In return it provides towering foliage, beautiful flowers, and wildlife habitat. Thanks to these traits, it’s grown and sold widely in aquatic plant nurseries. Powdery Alligator-Flag is also a host plant for the Brazilian Skipper butterfly (Calpodes ethlius), a large golden-brown skipper common in subtropical regions where Canna and Thalia plants are abundant. These butterflies are scarce in South Carolina but locally abundant where Powdery Alligator-Flag is established.
