Alligator Flag, Water Canna

Native to tropical America, the Water Canna or Alligator Flag is a perennial, aquatic plant for shallow water or the margins of ponds and lakes. An emergent, broad-leaved plant with rosettes of leaves on narrow stems, T. dealbata can reach a height of 2 metres. The large, long-petioled leaves, as wide as 45 cm, are alternate and sheathed with broad, lance-shaped, and veined leaf blades. The bold, dramatic foliage is reminiscent of Bird of Paradise leaves. The lavender-purple flowers are gracefully borne on open, bracteate, dangling clusters on very long, thin stems throughout the summer. All parts of the plant are covered with a white, powdery coating. A further species, Thalia geniculata, is slightly smaller, and has characteristic red stems at the base. The Water Canna is best in full sun; in Arriyadh, a position in partial shade is better. Plants are not frost-hardy, so that the plant will die back in very cold weather, and re-emerge in the spring. Propagation is by seed or root division. Pests include aphids. A robust, tropical plant, its natural habitats are lakes, swamps, and rivers. T. dealbata is most commonly cultivated for large ponds or the edges of lakes. It will also look well in a large water jar. Maintenance and fertilising are necessary to keep the plant in good condition.