INVASIVE ALIENS: CANNA INDICA

The common garden plant, Canna indica (Indian shot), has been declared as an alien invader plant in South Africa, falling into Category 1b of the National Environmental Management: Biodiversity Act which means it must be removed from your garden. To prevent these tough perennial plants from spreading, it is best to remove them carefully, ensuring that all the dense clumps of tubers have also been dug out. Unfortunately, the Canna indica has the propensity to invade stream banks, forests and other natural areas, crowding out and destroying the indigenous vegetation.

Note both the narrow leaves and the narrow red flowers.

Canna indica is a tall and vigorous grower, bearing copious small and narrow mainly red flowers. The green or bronze leaves are also narrow. The flowers are followed by fruits that are at first green and spiny. These turn brown before splitting open and releasing multitudes of black, pea-like seeds with a hard outer coating. This plant spreads by seed and underground rhizomes.

The seed pods are visible.

As with so many garden plants have proved to be invasive, Canna indica was introduced as an ornamental plant – they originate from the Caribbean and tropical America.