Gymnanthemum myrianthum | Plantz Africa about:reader?url=http://pza.sanbi.org/gymnanthemum-myrianthum
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Gymnanthemum myrianthum | Plantz Africa
Introduction
An unusual, striking, robust shrub or small tree that is suddenly beautiful when in flower in late autumn, with eye-catching clumps of mauve to white to deep purple flowers at the ends of its branches.
Description
Description
A soft-wooded tree or a large spreading shrub, 2–6 m tall, with robust, angular, upright stems, that all arise from the base of the plant, sparsely branched. The large, elliptical, 300 × 120 mm, grey-green leaves are attached with long stalks and taper to a pointy tip. The leaves have serrated edges and alternate with each other along the stems. The underside of the leaves are covered in a downy layer of small hairs.
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The ‘flowers’, as with all the members of the daisy family, are actually flower heads composed of many tiny florets, clustered together in a dome-shaped inflorescence, in winter, from June to August. The flower heads clump together at the tips of the stems and each exhibits a range of colours from magenta to purple, and occasionally pink or white.
Seeds form soon after flowering and turn the flower heads into bundles of attractive, fluffy white seed heads.
Conservation Status
Status
Gymnanthemum myrianthum is not threatened in its natural habitat and is assessed as
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Least Concern (LC) on the Red List of South African plants.
Distribution and habitat
Distribution description
Gymnanthemum myrianthum occurs naturally in South Africa, where it is found in riverine vegetation, on forest margins and bushy places in KwaZulu-Natal, Limpopo and Mpumalanga, as well as in Swaziland and northwards to tropical Africa, in Tanzania and also Kenya, usually as a secondary pioneer in disturbed ground.
Derivation of name and historical aspects
History
Gymnanthemum means ‘naked flower’, from the Greek gymnos . meaning ‘naked’ and anthemon meaning ‘flower’. The specific epithet, myrianthum , is derived from Greek murioi , meaning ‘many’ and anthemon , ‘a flower’, referring to the multitude of flowers this plant bears.
Gymnanthemum myrianthum was until recently known as Vernonia myriantha . Vernonia was a very large genus of over 1 000 species of annuals, perennials, shrubs and trees. Occurring in America, Africa, Asia, Madagascar and Australia, with approximately 40 species in southern Africa, widespread throughout South African provinces, but absent in the Western Cape. Some of these species are edible and have economic value, and they are all known for their deep purple flowers. This genus is named for the English botanist, William Vernon, who collected many plants in America and who died in 1711. There were numerous distinct subgenera and subsections in Vernonia , which led botanists to divide this large genus into several distinct genera. Most of the South African vernonias are now classified in the genera Gymnanthemum , Hillardiella , Linzia , Vernonella , Vernoniastrum , Baccharoides , Distephanus , Orbivestus , Cyanthillium , Pegolettia , Erlangea , Pleiotaxus and Polydora , but many are still known as ‘vernonia’ and keep their
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former botanical name in their common names.
There are many other very attractive South African vernonias which deserve more horticultural attention, including the silvery leaved Hilliardiella aristata (= Vernonia natalensis) , Hilliardiella oligocephala (= Vernonia oligocephala) with bicoloured leaves, the climbing and scrambling Gymnanthemum mespilifolium (= Vernonia mespilifolia) and the upright perennial Linzia glabra (= Vernonia glabra), which is widely used in the mixed herbaceous borders in Kirstenbosch National Botanical Garden.
Ecology
Ecology
Gymnanthemum myrianthum flower heads are visited by butterflies, beetles and bees, and Charaxes butterflies breed on them, although the leaves are poisonous to stock.
The seeds are enclosed in lightweight hairy fruits and these are dispersed by the wind with the help of a ‘parachute’ of bristly hairs.
The alien invasive Solanum mauritianum (Bugweed) resembles Gymnanthemum myrianthum , as both are tall, softwood shrubs with prominent false stipules, but on closer inspection, it is quite easy to tell them apart. The flowers and fruit are completely different, and if these are present, the species are easily distinguished and when not in flower or fruit, the main differences are that Solanum mauritianum has a light grey-green appearance with leaves that have entire, smooth margins, whereas Gymnanthemum myrianthum is dark green and has serrated edges to its leaves.
Uses
Use
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There are no recorded medicinal uses for Gymnanthemum myrianthum , and its leaves are toxic to stock. It has use as an ornamental in horticulture.
Growing Gymnanthemum myrianthum
Grow
This plant makes a bold statement, with its size and large leaves, but is easy to miss until it flowers, when it is becomes strikingly eye catching. It is relatively fast growing and, it doesn’t take long before it flowers. Grow Gymnanthemum myrianthum in a warm sunny position where it can get plenty of space, but also have its somewhat unattractive, slightly untidy, multi-stemmed base hidden behind denser and slightly shorter plantings.
Plants are best pruned back by a third each year after flowering and seeding, to encourage a more compact shape, but at Kirstenbosch we just leave the plants to robustly stretch up as far as they would like to. Requiring only this minimal annual maintenance, with regular applications of compost, although it needs water in spring and summer, it grows well with moderate to low watering in summer, once it is established, so it is useful for water-wise gardening in a larger space.
Gymnanthemum myrianthum can be propagated by seed sown in spring or early summer. The large quantities of small, fluffy fruits germinate well if sown immediately. The seeds are not long-lived and do not keep well if not refrigerated for storage.
New plants are easy to propagate from cuttings, which can be done throughout the year, with best results obtained in autumn. The roots form easily on semi-hard stem cuttings and on slightly softer tip cuttings, after treatment with rooting hormone powder. Cuttings usually root within a month and are ready to be planted out into the garden within 3 to 4 months.
References
Boon, R. 2010. Pooley's trees of eastern South Africa, a complete guide. Flora & Fauna Publications Trust, Durban.
Germishuizen, G. & Clarke, C. 2003. Illustrated guide to the wildflowers of northern South Africa. Briza Publications, Pretoria.
Hutchings, A., Scott, A.H., Lewis, G. & Cunningham, A.B. 1996. Zulu medicinal plants: an inventory. University of Natal Press, Pietermaritzburg.
Leistner, O.A. (ed.). 2000. Seed plants of southern Africa: families and genera.
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Strelitzia 10. National Botanical Institute, Pretoria.
Manning, J. 2003. Photographic guide to the wildflowers of South Africa. Briza Publications, Pretoria.
Pooley, E. 1993. The complete field guide to trees of Natal, Zululand and Transkei. Natal Flora Publication Trust, Durban.
Raimondo, D., Von Staden, L., Foden, W., Victor, J.E., Helme, N.A., Turner, R.C., Kamundi, D.A. & Manyama, P.A. (eds) 2009. Red list of South African plants 2009. Strelitzia 25. South African National Biodiversity Institute, Pretoria.
Credits
Cherise Viljoen and Alice Notten Kirstenbosch National Botanical Garden December 2016
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