Cannomois virgata is a fast-growing reed-like plant and is the only member of the genus to be found on the Cape Peninsula.
Cannomois virgata used to be the common scientific name for a group of three reed-like plants varying in height from 1.5–5.0 m tall. Until recently C. grandis and C. robusta were grouped within the Cannomois virgata species complex . Professor Peter Linder at the University of Zurich, Switzerland, recognised these different features and accordingly split the complex into three distinct species:
- Cannomois virgata— plants growing to a height of 1.0–1.5 m
- Cannomois robusta— plants growing to a height of 1.5–2.0 m
- Cannomois grandis— plants growing to a height of 5 m
Cannomois virgata is also distinct from the other two species in that it has a clumped growth form while the other two are tufted. Furthermore, C. virgata resprouts from its underground rhizome after fire while C. robusta and C. grandis are killed by fire and re-establish from seed.
Cannomois virgata has a vigorous spreading rhizome that can grow to have a basal diameter of 3-6m. Culm growth is mostly upright, sometimes arching. At each node lots of green growth gives the plant a full appearance.
Mass flowering is stimulated by fire and in the years following fire female plants will flower less and less eventually stopping entirely. Flowering occurs from October to January and seed is produced almost a year later. The seed is a little black nut measuring 9-12mm long.
Cannomois virgata is Red Listed as Least Concern. Current populations are widespread and stable.
Distribution and habitat
Cannomois virgata is widespread and often common in coastal areas. Inland it grows on south-facing mountain slopes at altitudes of 30–1 800 m. It is restricted to fynbos growing in sandstone or shale soils and receives an annual rainfall of 250–2 600 mm.
It occurs from the Cape Peninsula throughout the southwestern mountains to the Outeniqua Mountains in the Eastern Cape.
Plants are in cultivation in the northern hemisphere but do need to be protected against frost and cannot survive in frozen or very wet, cold soils.
Derivation of name and historical aspects
The name Cannomois is derived from the Greek, canna for cane and omoios meaning similar. The specific epithet, virgata, means twiggy or branching, alluding to the branching habit of the species.
Cannomois virgata belongs to the large southern hemisphere family of Restionaceae, which constitutes more than 400 species of about 40 genera in southern Africa, Australia, Madagascar, Indo-China and Chile. About 357 species occur in Africa, most of them in the Cape Floristic Region. Currently 13 species of Cannomois have been described.
The best known restio in South Africa is Thamnochortus insignis, which is widely used as a long-lasting thatching material.
Like all other Restionaceae, Cannomois virgata is wind pollinated. The seeds are large and have elaiosomes attached to them. Elaiosomes are protein-rich white waxy coatings on the outside of the seeds which are very attractive to ants. Once the seeds are ripe, they fall out of the inflorescence and are carried away by ants almost as soon as they hit the ground. The ants carry them to their nests, eat away the elaiosomes and leave the seed undamaged and safe from large seed-eating predators such as mice and shrews.
Uses and cultural aspects Species belonging to the genus Cannomois have been used by South Africans for hundreds of years, in the past as brooms and are now gaining popularity in the cut-flower industry. Smith (1966) writes that restios were probably used long before the first botanists saw restios being used as brooms and as thatching material.
The finely branched stems are particularly suitable for making brooms. The stems are cut and dried in the sun, the inflorescences are cut off and the stems are tied to a broomstick or strong handle. The common name besemriet refers to this.
Cannomois grandis is used widely in the cut-flower industry.
Cannomois virgata has horticultural potential as a landscaping plant. However, due to the difficulty of propagating it, it is not widely used or available in the trade.
Growing Cannomois virgata
Cannomois virgata is a resprouter and rarely produces seed, so propagation by germination is untested at Kirstenbosch.
The recommended method of propagation is through vegetative propagation which is done during winter. Dig up mature plants and divide the rhizomes into large chunks. Remove the ‘leafy' culm growth. Plant into a well-drained soil and keep moist. Treatment with a seaweed extract once a month will encourage new root and shoot growth in spring once the weather warms up.
Plant Cannomois virgata in a sunny position in well-drained soil and water regularly. Plants require a large area to grow in or an area that is able to confine roots like a planter box, as the rhizomes tend to spread out over a large area over time. Tidy up plants by removing straggly and dead culms as they appear. If plants are looking old and tired stimulate new growth by cutting the culms down to the ground in late autumn. This emulates what a fire would do in nature.
Use liberal amounts of compost to improve the soil. You can also apply an organic fertiliser low in phosphates twice a year for lush green growth, although this is not essential. Cannomois virgata is generally free from pests and diseases.
Cannomois virgata is suited to an informal garden style where the branching willowy culms will create texture and movement in the garden. Combine it with sturdy plants that will be able to grow above and through the spreading rhizomes. A few examples of planting companions are Aristea capitata , Watsonia borbonica , Berzelia abrotanoides , Leucadendron argenteum , Podalyria calyptrata and Polygala virgata.
References and further reading
- Brown, N., Jamieson, H. & Botha, P. 1998. Grow restios . Kirstenbosch Gardening Series. National Botanical Institute, Cape Town.
- Dorrat-Haaksma, E. & Linder, H.P. 2000. Restios of the Fynbos . The Botanical Society of South Africa, Cape Town.
- Dorrat-Haaksma, E. & Linder, H. P. 2012. Restios of the Fynbos . Struik Nature, Cape Town.
- Foden, W. & Potter, L. 2005. Cannomois virgata (Rottb.) Steud. National Assessment: Red List of South African Plants version 2013.1. http://redlist.sanbi.org/
- Goldblatt, P. & Manning, J. 2000. Cape Plants. A conspectus of the Cape flora of South Africa. Strelitzia 9. National Botanical Institute, Pretoria.
- Linder, H.P. 1985. Conspectus of the African species of Restionaceae. Bothalia 15: 387–503.
- Linder, H.P. 1991. A review of the southern African Restionaceae. Contributions from the Bolus Herbarium No. 13.
- Linder, H.P. 2011. African Restionaceae version 6 . CD. University of Zurich, Switzerland.
- Smith, C.A. 1966. Common names of South African plants. Memoirs of the Botanical Survey of South Africa No. 35.
Updated by Louise Nurrish