Plant 268

Canna indica L. (Cannaceae)

Indian shot

Indian shot plants are most familiar for their vivid yellow-, red- or orange-coloured flowers and broad, stalked leaves that bring a tropical feel to temperate planting schemes. Canna is a small genus of herbaceous plants naturally distributed through the tropical Americas. Hundreds of scientific names have been applied to a handful of species, giving an indication of their variability. The closest relatives of the canna family (which only contains the genus Canna) are the gingers, marantas and costas.

The cane-like flowering stems of Indian shot can be up to three metres tall and arise from short, distinctive, starch-rich underground stems (rhizomes). Indian shot rhizomes have been discovered in archaeological digs from numerous parts of the Americas. They have been cultivated by peoples in the Americas for thousands of years as a foodstuff. The rhizomes can readily be identified based on their starch grains; with diameters up to 0.15 mm, they are the largest known starch grains of any flowering plant. It is thought that Indian shot domestication first occurred in the northern Andes.

Indian shot is a multipurpose plant. The young leaves are edible, whilst all parts of the plant are used as animal fodder. The flowering stem produces a jute-like fibre, whilst artificial wetlands planted with Indian shot are used to clean industrial effluent.

The common name Indian shot is a reference to the more-or-less spherical, hard, black seeds that are about the size of lead shot. These seeds have been used as ammunition, beads, musical instruments, and even as a coffee substitute. In the late 1960s, an Indian shot seed, approximately 550 years old, recovered from inside a rattle buried in an Argentinian tomb, germinated and the plant went on to flower.

The intricate structure of the Indian shot flower implies there are associations with specific pollinators. Flower size and colour, together with the production of nectar and the absence of scent indicates they Indian shot is pollinated by birds, although pollinators have rarely been observed visiting the flowers.

European interest in Indian shot, as a horticultural curiosity, may extend back to the early sixteenth century and, by the end of the following century, it was recorded from southeast India. From the mid-nineteenth century, horticultural selections, made from species hybrids, produced the great range of leaf patterns and flower colours, form and sizes now seen. Today, Indian shot is naturalised across many tropical, subtropical and warm temperate regions.

Further reading

Maas-Van De Kamer H and Maas PJM 2008. The Cannaceae of the world. Blumea 53: 247-318.

National Research Council 1989. Lost crops of the Incas: little-known plants of the Andes with promise for worldwide cultivation. The National Academies Press.

Ugent D et al. 1984. New evidence for ancient cultivation of Canna edulis in Peru. Economic Botany 38: 417-432.

Stephen Harris