Canna (plant)

The plants are large tropical and subtropical herbaceous perennials with a rhizomatous rootstock. The broad, flat, alternate leaves that are such a feature of these plants, grow out of a stem in a long, narrow roll and then unfurl. The leaves are typically solid green, but some cultivars have glaucose, brownish, maroon, or even variegated leaves. ==Taxonomy==

History The name Canna originates from the Latin word for a cane or reed. Canna indica, commonly called achira in Latin America, has been cultivated by Native Americans in tropical America for thousands of years, and was one of the earliest domesticated plants in the Americas. The starchy root is edible. The first species of Canna introduced to Europe was C. indica, which was imported from the East Indies, though the species originated from the Americas. Charles de l'Ecluse, who first described and sketched C. indica, indicated this origin, and stated that it was given the name indica, not because the plant is from India, in Asia, but because this species was originally transported from America: Quia ex America primum delata sit; and at that time, one described the tropical areas of that part of the globe as the West Indies. Much later, in 1658, Willem Piso made reference to another species that he documented under the vulgar or common name of 'Albara' and 'Pacivira', which resided, he said, in the "shaded and damp places, between the tropics"; this species is C. angustifolia L. (later reclassified as C. glauca L. by taxonomists). and Nobuyuki Tanaka from Japan. Both reduced the number of species from the 50–100 accepted previously, assigning most as synonyms. This reduction in species is also confirmed by work done by Kress and Prince at the Smithsonian Institution, but this only covers a subset of the species range. ==Distribution==

, Cuba The genus is native to tropical and subtropical regions of the New World, from the Southern United States (southern South Carolina west to southern Texas) and south to northern Argentina. Canna cultivars are grown in most countries, even those with territory above the Arctic Circle, which have short summers, but long days, and the rapid growth rate of cannas makes them a feasible gardening plant, as long as they receive 6–8 hours of sunlight each day during the growing season and are protected from the cold of winter. == Ecology ==

Pests Cannas are largely free of pests. However, in the eastern and southern United States, plants sometimes fall victim to the canna leaf roller moth, with the resultant leaf damage, while not being fatal to the plant, can be most distressing to a keen gardener's eye. These pests, while certainly able to drain a plant of its energy over time, and cause its eventual decline, are generally not lethal to the plant when dealt with immediately. The majority of insect pests on canna plants can be sprayed with a 70% isopropyl alcohol mist—diluted slightly—applied during non-sunny periods, as the alcohol may cause sunburn on the plant. Other effective options include insecticidal soap, neem and horticultural oils, and other commercially available spray treatments. Granulated systemic insecticides are also useful, and generally completely safe; when applied to the soil topically every few months, granulated or powdered systemics will prevent nearly all pest infestations (for the duration of effectiveness). Non-scented baby wipes or paper towels, moistened with rubbing alcohol or cider vinegar may be used to wipe any invisible eggs or larvae from the leaves. Disease Cannas are remarkably free of diseases, compared to many genera. However, they may fall victim to canna rust, a fungal disease resulting in orange spots on the plant's leaves, caused by over-moist soil. They are also susceptible to certain plant viruses, some of which are Canna-specific, which may result in spotted or streaked leaves, in a mild form, but can finally result in stunted growth and twisted and distorted blooms and foliage. The flowers are sometimes affected by a grey, fuzzy mold called botrytis. Under humid conditions, it is often found growing on the older flowers. Treatment is to simply remove the old flowers, so the mold does not spread to the new flowers. ==Cultivation==

Cannas grow best in full sun with moderate water in well-drained, rich or sandy soil. They grow from perennial rhizomes, but are frequently grown as annuals in temperate zones for an exotic or tropical look in the garden. In arid regions, cannas are often grown in the water garden, with the lower inch of pot submerged. In all areas, high winds tear the leaves, so shelter is advised. The rhizomes are sensitive to frost and will rot if left unprotected in freezing conditions. In areas with winter temperatures below in the winter (< USDA Zone 8b), the rhizomes can be dug up before freezing and stored (above ) for replanting in the spring. Otherwise, they should be protected by a thick layer of mulch over winter. ==Uses==

• Some species and many cultivars are widely grown in the garden in temperate and subtropical regions. Sometimes, they are also grown as potted plants. A large number of ornamental cultivars have been developed. They can be used in herbaceous borders, tropical plantings, and as a patio or decking plant. • Internationally, cannas are one of the most popular garden plants, and a large horticultural industry depends on the plant. • The rhizomes of cannas are rich in starch, and have many uses in agriculture. All of the plant material has commercial value, rhizomes for starch (consumption by humans and livestock), stems and foliage for animal fodder, young shoots as a vegetable, and young seeds as an addition to tortillas. • The seeds are used as beads in jewelry. • The seeds are used as the mobile elements of the kayamb, a musical instrument from Réunion, as well as the hosho, a gourd rattle from Zimbabwe, where the seeds are known as hota seeds. • In more remote regions of India, cannas are fermented to produce alcohol. • The plant yields a fibre from the stem, which is used as a jute substitute. • A fibre obtained from the leaves is used for making paper. The leaves are harvested in late summer after the plant has flowered, they are scraped to remove the outer skin, and are then soaked in water for two hours prior to cooking. The fibres are cooked for 24 hours with lye and then beaten in a blender. They make a light tan to brown paper. • In Thailand, cannas are a traditional gift for Father's Day. • In Vietnam, canna starch is used to make cellophane noodles known as miến dong. • Cannas attract hummingbirds, so can be part of a pollinator and wildlife habitat strategy. Horticultural varieties (cultivars) Cannas became very popular in Victorian times as garden plants, and were grown widely in France, Germany, Hungary, India, Italy, the United Kingdom, and the United States. C. × ehemannii is tall and green-leafed with terminal drooping panicles of hot pink iris-like flowers, looking somewhat like a cross between a banana and a fuchsia. As tender perennials in northern climates, they suffered severe setbacks when two world wars sent the young gardening staff off to war. The genus Canna has recently experienced a renewed interest and revival in popularity. See List of Canna hybridists for details of the people and firms that created the current Canna legacy. In the early 20th century, Professor Liberty Hyde Bailey defined, in detail, two "garden species" (C. × generalis and C. × orchiodes) to categorise the floriferous cannas being grown at that time, namely the Crozy hybrids and the orchid-like hybrids introduced by Carl Ludwig Sprenger in Italy and Luther Burbank in the U.S., at about the same time (1894). The definition was based on the genotype, rather than the phenotype, of the two cultivar groups. Inevitably over time, those two floriferous groups were interbred, the distinctions became blurred and overlapped, and the Bailey species names became redundant. Pseudo-species names are now deprecated by the International Code of Nomenclature for Cultivated Plants which, instead, provides cultivar groups for categorising cultivars (see groups at List of Canna cultivars). AGM cultivars These canna cultivars have gained the Royal Horticultural Society's Award of Garden Merit: • 'Alaska' (cream flushed yellow) • 'Annaeei' (large blue-green leaves) • C. × ehemannii (deep pink) • 'Erebus' (coral pink) • 'General Eisenhower' (bronze leaves, orange flowers) • 'Louis Cayeux' (salmon pink) • 'Musifolia' (large leaves flushed bronze) • 'Mystique' (bronze leaves) • 'Phasion' (bronze leaves, orange flowers) • 'Picasso' (yellow spotted red flowers) • 'Russian Red' (bronze leaves) • 'Shenandoah' (flesh pink) • 'Verdi' (bright orange) • 'Whithelm Pride' (bright pink) • 'Wyoming' (bright orange) Agricultural varieties The Canna Agriculture Group contains all of the varieties of Canna grown in agriculture. "Canna achira" is a generic term used in South America to describe the cannas that have been selectively bred for agricultural purposes, normally derived from C. discolor. It is grown especially for its edible rootstock from which starch is obtained, but the leaves and young seeds are also edible, and achira was once a staple food crop in Peru and Ecuador. Many more traditional kinds exist worldwide; they have all involved human selection, so are classified as agricultural cultivars. Traditionally, Canna edulis Ker Gawl. has been reputed to be the species grown for food in South America, but C. edulis probably is simply a synonym of C. discolor, which is also grown for agricultural purposes throughout Asia. Propagation Sexual propagation Seeds are produced from sexual reproduction, involving the transfer of pollen from the stamen of the pollen parent onto the stigma of the seed parent. ;Pollination The species are capable of self-pollination, but most cultivars require an outside pollinator. All cannas produce nectar, so attract nectar-consuming insects, bats, and hummingbirds, that act as the transfer agent, spreading pollen between stamens and stigmas on the same or different flowers. ;Genetic changes Since genetic recombination has occurred, a cultivar grown from seed will have different characteristics from its parent(s), thus should never be given a parent's name. The wild species have evolved in the absence of other Canna genes and are usually true to type when the parents are of the same species, but a degree of variance still occurs. The species C. indica is an aggregate species, having many different and extreme forms ranging from the giant to miniature, from large foliage to small foliage, both green and dark foliage, and many differently coloured blooms of red, orange, pink, or yellow, and combinations of those colours. Asexual propagation ;Division of plant parts Outside of a laboratory, the only effective asexual propagation method is rhizome division. This uses material from a single parent, and as no exchange of genetic material occurs, it almost always produces plants that are identical to the parent. After a summer's growth, the horticultural cultivars can be separated into typically four or five separate smaller rhizomes, each with a growing nodal point (growing eye). Without the growing point, which is composed of meristem material, the rhizome will not grow. ;Micropropagation Micropropagation, also known as tissue culture, is the practice of rapidly multiplying stock plant material to produce a large number of progeny plants. Micropropagation uses in vitro division of small pieces in a sterile environment, where they first produce proliferations of tissue, which are then separated into small pieces that are treated differently so that they produce roots and new stem tissue. The steps in the process are regulated by different ratios of plant growth regulators. Many commercial organizations have produced cannas this way, and specifically the "Island Series" of cannas was introduced by means of mass-produced plants using this technique. However, cannas have a reputation for being difficult micropropagation candidates. Micropropagation techniques can be employed to disinfest plants of a virus. In the growing tip of a plant, cell division is so rapid that the younger cells may not have had time to be infected with the virus. The rapidly growing region of meristem cells producing the shoot tip is cut off and placed in vitro, with a very high probability of being uncontaminated by virus.