CANNA TAXONOMY
| Taxonomy is the science of classifying
and naming things. Living things are classified according to the system developed by Carl Linneus in the 16th century. His system is based on presumed evolutionary relationships. His broadest classification is Kingdom, and so we have the Plant Kingdom, the Animal Kingdom, etc. (there are others, such as fungi, bacteria, viruses etc). Below Kingdom, there are a number of other broad classifications such as Class, Order, Family, Genus and Species. The species is the finest level of classification normally used to define naturally ocurring individual types of living thing. Lineaus also introduced the system where each type of naturally occurring living thing is given a name in 2 parts. So we have, for example, Canna indica. The first part Canna, refers to the genus, and the second part indica refers to the species. Maybe I should mention something about which botanists are quite picky, and where non-experts can and often do make a mistake. Note that the genus always begins with a capital letter, and the species always begins with a lower case letter. So, writing Canna indica is correct. Writing Canna Indica displays your ignorance. So, starting again, Cannas are members of the Plant Kingdom. Next, they are flowering plants, which differentiates them, for example, from mosses, ferns, cycads, conifers, etc, which do not produce flowers. Next, they are monocots. This is where it starts to get difficult. All flowering plants are divided into 2 groups. They are either monocots or dicots. Monocots are plants which start from the seed with a single seed leaf. Dicots start with 2 equal seed leaves. So, for example, lilies, irises, orchids, grasses, onions, bananas, gladiolus, daffodils, snowdrops, palm trees, belong to the monocots, whereas plants such as roses, cacti, apples, peas, cabbages, poppies, daisies, oak trees, waterlilies, etc belong to the dicots. As a rough generalisation, monocots have narrow leaves and leaf veins which are parallel, whereas dicots have vide leaves leaves and the leaf veins are usually branched. Another difference between monocots and dicots is that monocots have flower parts in 3's or multiples of 3. Ie they have 3 or 6 petals etc. Dicots generally have flowers with 4 or 5 petals, or multiples thereof. Next, they belong to a group of monocots known as the Zingiberales, which include the following few plant families: Zingiberaceae (the
ginger family)
Musaceae (the banana family) Strelizeaceae (bird of paradise flower family) Marantaeceae (prayer plant family) Cannaceae (canna
family).
So canna plants have their own plant Family within the plant Kingdom. It is unusual for a plant to have its own plant family. What is also unusual is that within the Canna family there is ony one genus, the Canna genus. This means that cannas are quite different from other plants, and are seperated from them by a wide gap in evolution. This is why cannas are so unusual, and so interesting. Having said just above that canna is a monocot and monocots have 3 petals, it can be seen that most cannas appear to have 4 petals. This is an optical illusion. What appears to be petals in a canna flower are not petals at all. They are actually sterile stamens called staminodes. The true petals are much smaller and often not noticed, and there are 3 in number. Within the Canna genus there are a number of species. At one time botanists thought there were hundreds of species, and even now many canna are described in the horticultural literature as being species when the latest botanical information is that such species don't exist. A recent taxonomic study by Nobuyuki Tanaka (Makino, Japan) reduced the number of species to those listed below:
* indicates those species that are sometimes grown as garden plants. Some species make attractive and interesting garden plants, though it should be cautioned that often canna species are wrongly named in seedsmens catalogues and garden centres. Generally speaking, canna species have small flowers. The large flowered cannas that are commonly grown in gardens, and that are naturalised throughout the world in tropical countries, are hybrids that have been bred by horticulturalists. The breeding of garden hybrids began in the mid 1800's, and since that time several thousand have appeared in horticultural catalogues. |