Canna is a genus of large tropical and subtropical herbaceous perennials in the family Cannaceae, order Zingiberales, comprising approximately 10–20 accepted wild species alongside a vast range of cultivated hybrids. Plants grow from fleshy, starch-storing rhizomes and are native to the New World, ranging from the southern United States (southern South Carolina west to southern Texas) south through Central America to northern Argentina, with introduced and naturalized populations now established on every inhabited continent.
The plants are notable for their bold, paddle-shaped leaves — up to 60 cm long — which range in colour from fresh green to glaucous, reddish-purple, and bronze, depending on the cultivar. Stems are robust and can reach 2–3 metres in wild species and up to 2.4 metres in cultivated selections. Flowers are borne on terminal spikes or panicles and are asymmetric; the three petals remain small and concealed beneath conspicuous, petal-like staminodes (modified stamens) in shades of red, orange, yellow, pink, or cream, often multi-coloured. Bloom time runs from midsummer through autumn, and the fruits are prickly, three-valved capsules containing hard, rounded seeds.
Canna × generalis — the garden canna or canna lily — encompasses the thousands of horticultural cultivars derived from various wild species; it is one of the most widely grown summer-flowering perennials in temperate gardens worldwide. The name Canna comes from the Latin word for a cane or reed, a reference to the tall, reed-like stems.
Etymology
The genus name Canna is derived from the Latin word for a cane or reed, alluding to the tall, hollow-stemmed habit of wild plants. The species epithet of the best-known wild member, Canna indica, does not denote Indian origin; the plant is American but reached Europe via East Indies trade routes, and Charles de l'Ecluse, who first described and illustrated it in the 16th century, recorded the name it bore in commerce.
Distribution
Wild Canna species are native to the tropical and subtropical New World, from the southern United States (southern South Carolina westward to southern Texas) through Mexico and Central America to northern Argentina. The genus is most diverse in the Andean foothills and the Amazon basin. Canna indica has naturalized throughout the tropics and subtropics globally — including Africa, South and South-East Asia, and Pacific islands — and is considered invasive in some regions.
Ecology
Cannas thrive in warm, humid environments with high light availability and prefer moist, nutrient-rich soils, though they tolerate pH values from 4.5 to 8.0. The genus is relatively disease-resistant; the main threats are canna rust (a fungal disease promoted by excess moisture), viral infections causing leaf spotting, and botrytis mould on senescing flowers. Common animal pests include the canna leaf roller moth, slugs, snails, red spider mites, mealybugs, scale insects, and Japanese beetles. In wetland settings, cannas are used in constructed phytoremediation systems to extract pollutants from water and soil. The flowers are visited by hummingbirds, and the plants serve as larval host plants for several moth species.
Cultivation
Cannas are grown outdoors year-round in USDA hardiness zones 7–11 and as seasonal perennials or container plants in cooler regions. They prefer a deep, organically rich, well-drained soil in full sun, though they tolerate partial shade and a range of soil textures provided moisture is adequate during the growing season. Good drainage is essential: waterlogged soil causes rhizome rot. Plants dislike strong wind, which shreds the large leaves.
In frost-prone areas (below approximately −10 °C / 14 °F), rhizomes must be lifted after the first frost, allowed to dry briefly, and stored in barely moist medium at a minimum of 4–7 °C (40–45 °F) through winter. They are replanted when frost risk has passed in spring. In zones 6a–6b, plants are cut to ground level immediately after the first frost before lifting.
Propagation
The standard propagation method for cannas is division of rhizomes in spring. Each division must include at least one viable growing point (eye). Divisions establish quickly in warm soil.
Propagation from seed is possible but less common for named cultivars (which do not come true from seed). Seeds have an exceptionally hard coat and require scarification: pre-soaking for 24 hours in warm water before sowing is standard practice. Seeds are sown in February or March in a warm greenhouse maintained at around 20 °C.
Cultural Uses
Canna has been cultivated for food, fibre, and ornament by indigenous Americans for thousands of years. Canna indica (achira) is one of the earliest domesticated plants in the Americas. The starchy rhizomes contain roughly 25% starch and are consumed cooked or, in some traditions, raw; the starch functions as an arrowroot substitute and is used in Vietnam to make cellophane noodles. Young shoots are cooked and eaten as a green vegetable, contributing meaningful protein. Immature seeds are ground into flour for inclusion in tortillas.
Beyond food, the hard seeds are strung as beads in jewellery and used as rattle elements in percussion instruments such as the kayamb and hosho. Leaf fibre can substitute for jute and has been used to make paper. The seeds yield a purple dye, and smoke from burning leaves has been used as a natural insecticide. In Thailand, cannas are a traditional Father's Day gift. In modern horticulture and ecological engineering, cannas are deployed in constructed-wetland systems for phytoremediation of agricultural and industrial runoff.
Taxonomy Notes
Canna L. was formally established by Linnaeus in Species Plantarum (1753) and is the sole genus of the family Cannaceae. It is placed in the order Zingiberales, which also contains gingers, bananas, heliconias, and bird-of-paradise plants.
Historically, botanists recognised 50–100 species; in the late 20th century taxonomists Paul Maas and Nobuyuki Tanaka substantially revised the genus downward to approximately 10–20 accepted wild species, transferring most formerly recognised entities to synonymy. GBIF currently lists 64 descendant taxa across accepted species, synonyms, and cultivars. The widespread horticultural canna is Canna × generalis, a complex hybrid group of uncertain parentage.
History
Canna indica was among the earliest plants domesticated in the Americas, cultivated by indigenous peoples in tropical America for its starchy rhizomes over millennia before European contact. The first recorded introduction into Europe was via East Indies trade routes in the 16th century; Charles de l'Ecluse (Clusius) first described and illustrated it, naming it indica after its apparent origin — reflecting its port of embarkation rather than its true American homeland.
From the 16th century onwards, cannas spread rapidly through European ornamental gardens. Intensive 19th-century hybridisation — particularly by French and Italian breeders — produced the large-flowered, colourful Canna × generalis cultivars that remain the foundation of modern garden cannas. Cannas are now widely naturalised in tropical and subtropical regions worldwide.
