Canna (plant)

''Canna'' or canna lily is the only genus of flowering plants in the family Cannaceae, consisting of 10 species.The Cannaceae of the World, H. Maas-van der Kamer & P.J.M. Maas, BLUMEA 53: 247-318 Cannas are not true lilies, but have been assigned by the APG II system of 2003 to the order Zingiberales in the monocot clade Commelinids, together with their closest relatives, the gingers, spiral gingers, bananas, arrowroots, heliconias, and birds of paradise.

The plants have large foliage, so horticulturists have developed selected forms as large-flowered garden plants. Cannas are also used in agriculture as a source of starch for human and animal consumption. Khoshoo, T.N. & Guha, I. - Origin and Evolution of Cultivated Cannas. Vikas Publishing House

Although plants of the tropics, most cultivars have been developed in temperate climates and are easy to grow in most countries of the world, as long as they receive at least 6–8 hours average sunlight during the summer, and are moved to a warm location for the winter. See the ''Canna'' cultivar gallery for photographs of ''Canna'' cultivars.

The name ''Canna'' originates from the Latin word for a cane or reed.

Description

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.

The flowers are asymmetric and composed of three sepals and three petals that are small, inconspicuous, and hidden under extravagant stamens. What appear to be petals are the highly modified stamens or staminodes. The staminodes number (1–) 3 (–4) (with at least one staminodal member called the labellum, always being present. A specialized staminode, the stamen, bears pollen from a half-anther. A somewhat narrower "petal" is the pistil, which is connected down to a three-chambered ovary.

The flowers are typically red, orange, or yellow, or any combination of those colours, and are aggregated in inflorescences that are spikes or panicles (thyrses). The main pollinators of the flowers are bees, hummingbirds, sunbirds, and bats. The pollination mechanism is conspicuously specialized. Pollen is shed on the style while still in the bud, and in the species and early hybrids, some is also found on the stigma because of the high position of the anther, which means that they are self-pollinating. Later cultivars have a lower anther, and rely on pollinators alighting on the labellum and touching first the terminal stigma, and then the pollen.

The wild species often grow to at least in height, but wide variation in size exists among cultivated plants; numerous cultivars have been selected for smaller stature.

Cannas grow from swollen underground stems, correctly known as rhizomes, which store starch, and this is the main attraction of the plant to agriculture, having the largest starch grains of all plant life.

''Canna'' is the only member of the Liliopsida class (monocot group) in which hibernation of seed is known to occur, due to its hard, impenetrable seed covering.Grootjen, C. J. and F. Bouman. 1988. Seed structure in CannaceaeLerman, J. C. and E. M. Cigliano. 1971. New carbon-14 evidence for six hundred years old ''Canna compacta'' seed

Taxonomy

History

''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).

Without exception, all ''Canna'' species that have been introduced into Europe can be traced back to the Americas, and ''Canna'' definitely is solely an American genus. If Asia and Africa provided some of the early introductions, they were only varieties resulting from ''C. indica'' and ''C. glauca'' cultivars that have been grown for a long time in India and Africa, with both species imported from Central and South America. Since cannas have very hard and durable seed coverings, seed remains likely would survive in the right conditions and been found by archaeologists in the Old World if ''Canna'' had been grown there from antiquity. If the soils of India or Africa had produced some of them, they would have been imported before the 1860s into European gardens.Chaté, E. (1867).'' Le Canna, son histoire, sa culture. '' Libraire Centrale d'Agriculture et de Jardinage

Phylogeny

Species

Although most cannas grown these days are cultivars (see below), about 20 known species are of the wild form, and in the last three decades of the 20th century, ''Canna'' species have been categorized by two different taxonomists, Paul Maas, from the Netherlands Paul Maas 1985. 195. Cannaceae. & Maas, P. J. M. and H. Maas. 1988. 223. Cannaceae. and Nobuyuki Tanaka from Japan. Tanaka, N. 2001. Taxonomic revision of the family Cannaceae in the New World and Asia. Makinoa ser. 2, 1:34–43. 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

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.

''C. indica'' has become naturalized in many tropical areas around the world, is a difficult plant to remove, and is invasive in some places.

''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, but in the US, plants sometimes fall victim to the canna leaf roller moth, and the resultant leaf damage, while not fatal to the plant, can be most distressing to a keen gardener.

Slugs and snails are fond of cannas, and can leave large holes in the leaves, preferring the tender, young, unfurled leaves. Red spider mites can also be a problem for cannas grown indoors or during a very hot, long summer outdoors. Japanese beetles can also ravage the leaves if left uncontrolled.Plant Pest handbook
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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.Plants for a Future
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* 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.
* A purple dye is obtained from the seed.
* Smoke from the burning leaves is said to be insecticidal.
* Cannas are used to extract many undesirable pollutants in a wetland environment as they have a high tolerance to contaminants.
* 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. Some cultivars from this time, including a sterile hybrid, usually referred to as ''Canna'' × ''ehemannii'', are still commercially available.Canna Ehemannii
accessdate=25 July 2014 ''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. Once, hundreds of cultivars existed, but many are now extinct. In 1910, Árpäd Mühle, from Hungary, published his ''Canna'' book, written in German. It contained descriptions of over 500 cultivars.

In recent years, many new cultivars have been created, but the genus suffers severely from having many synonyms for many popular ones. Most of the synonyms were created by old varieties resurfacing without viable names, with the increase in popularity from the 1960s onwards. Research has accumulated over 2,800 ''Canna'' cultivar names, but many of these are simply synonyms. 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

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