Thalia dealbata, Alligator Flag or Powdery Alligator Flag is a stunning statuesque aquatic plant from North America and is the only member of the Marantaceae that is hardy. Its tall elegant stems give rise to elongated paddle-shaped foliage that create a dramatic and exotic atmosphere around the pond margin. In summer it produces a magnificent gem-like inflorescence of tightly clustered purple flowers and whitish bracts encrusted with a waxy powdery bloom giving it the appearance of a frosted art nouveau brooch or the jeweled sceptre of some underwater being.

For such a visually impressive plant, Thalia dealbata is surprisingly easy to cultivate. The only member of the Marantaceae that is aquatic in habit it requires a moist substrate and a pond margin is ideal although it is possible to grow it in other situations as long as there is constant moisture. A herbaceous perennial, it dies down to its rhizome in the winter months and it should be planted with its crown at least 30 cm beneath layes of sand, silt or mud to ensure it is insulated from winter freezes.