Kanna is officially known as Sceletium tortuosum: a member of the Aizoaceae or the Ice Plant family. The genus is part of the subfamily of Mesembryanthemoideae.
Usually eight species of Sceletium are recognised, although there’s no overall consensus about the exact categorisation of this family of plants. At least one of those Sceletium species, Sceletium expansum, is also known by the popular name kanna and different Sceletium species were used by the indigenous people of South-Africa. Formerly many of the Sceletium species were classified as Mesembryanthemum.
Kanna is believed to be related to the Pokeweed and Cactus (Cactaceae) families. Its cultivation and care are similar to the Cactaceae. Seeds should be scattered onto cactus or succulent soil, pressed down subtly and watered for propagation.
The genus Sceletium tortuosum was determined by N.E. Brown in 1925, who defined the succulent plant by its characteristic skeletonised leaf venation pattern visible in the dry leaves. On the fleshy, thick leaves little ‘bladder cells’, also called ‘idioblasts’, are visible.
The flowers of Sceletium tortuosum can be recognised by their threadlike petals that are usually white to yellow, but occasionally pale orange or pink as well. The fruit capsule contains kidney-shaped seeds which are brown to black in colour.
Sceletium tortuosum is a creeper plant that reaches about 30 cm in height. Usually it’s covering the ground in the shade of larger shrubberies.
Kanna grow conditions
The succulent leaves grow in pairs during the winter. In summertime the leaves die off, thereby skeletonising the lower stem in order to protect the plant from adverse environmental conditions. As a succulent, kanna is well equipped to deal with scarce water resources. By minimizing evaporation and using an excellent water storage ability, Sceletium tortuosum is able to survive in low-rainfall areas.
Active alkaloids like mesembrine, mesembrenone and tortuosamine can be found in the entire plant: from the roots to the stem and the leaves.
Most of the approximately 1000 species of Mesembryanthemoidaey are endemic to the arid and semi-arid regions of southern Africa. Sceletium tortuosum mainly grew in one particular area in South-Africa named ‘Kannaland’. This region is situated in the Western Cape province in the south of the country. In the earliest reports by Dutch colonists these areas were known as ‘the Little Karoo’ and ‘Namaqualand’. Sceletium tortuosum was also found in other dry areas of Western, Eastern and North Cape provinces of South-Africa.
Due to overharvesting, environmental changes and diseases, Sceletium tortuosum has become a rare sight in its natural habitat. It’s been introduced to other countries but with little success, as the plant is very sensitive to soil type and temperature.
Nowadays kanna is mainly cultivated in nurseries under controlled conditions. The plant seems to thrive well in these artificial environments that make use of hydroponics. The optimal temperature for the kanna plant is at least 16°C and it should never be exposed to frost.
Mesembrine, one of the main alkaloids in Sceletium, is found in many other species of the Aizoaceae family. The Griquas, a different ethnic group in South-Africa, are reported to use a snuff mixture named ‘keng-keng’ which contains tobacco and another genus of the Mesembryanthemaceae: the Rabaiea albinota. Another family member, Mesembryanthemum crystallinum, is reported to contain a high number of alkaloids as well. However, due to its equally high level of oxalates it may cause bladder or kidney stones which makes it less suitable for use.