The Cycad Collection of Vumba Botanical Garden, Zimbabwe
Volume 2 Number 8 - July 1997
Historically cycads were once one of the major components of the world's vegetation. They were grazed by dinosaurs, but little appears to have changed in their morphology and physiology, let alone their reproductive systems.
As of now there are 185 known species in 10 genera. The genera are, with countries of origin in brackets: Encephalartos (South Africa), Stangeria (South Africa), Bowenia (Australia), Zamia (New World), Cycas (more widespread - Asia, tropical Australia, East Africa, Madagascar and a host of western Pacific islands), Ceratozamia (Mexico), Dioon (Mexico and Honduras), Microcycas (Cuba), Macrozamia (Australia) and Lepidozamia (eastern Australia).
Cycads are toxic to both humans and livestock and have to be treated before consumption. The toxicity is due to glycosides such as cycasin, macrozamin and methylazoxmethanol which cause neurological disorders. To reduce the effects of these harmful substances, cycad seeds, leaves or stem tissues require slicing, sun-drying, fermenting or repeated steeping in bowls of water before consumption. Cycads are popular horticultural subjects, with specific links with religion (Palm Sundays). Other cycad uses include acting as windbreaks and providing fuelwood. The nitrogen-rich leaves are said to be employed as a fertilizer in rice and potato fields. Ornaments such as flasks, vases and small boxes can also be made from the caudex of this plant.
The objectives of this collection are to:
The threat to cycads is mainly from man:
Zimbabwe boasts three cycad species, these being Encephalartos manikensis, E. concinnus and E.chimanimaniensis. The E. chimanimaniensis colony used to lie on the border between Zimbabwe and Mozambique. The populations on the Zimbabwean side have been decimated. E. concinnus still exists in the wild on a private farm in the south western part of the country. We have personally visited one of the E. manikensis colonies where I estimated the standing plants to be above six hundred. Signs of vandalism were however, evident.
In so far as consumption of cycad materials by man is concerned, I have had no personal experience except what I have gleaned from the elders residing in the vicinity of the E. manikensis colony, as well as from the literature. During severe drought, the caudex of Encephalartos manikensis is trimmed of roots and leaves, pounded into pulp which is packed in hessian bags. The package is left in water for up to seven days for fermentation to occur. Thereafter the pulp is sun-dried and later ground to produce a powder that is utilised in making dough. The dough is then baked into some kind of bread that sustains the community until they can harvest other crops.
In addition, slides and photographs, ethnobotanical notes and herbarium specimens form an integral part of the project.
The Department of National Parks and Wild Life Management is responsible for the implementation of CITES and monitoring local trade. Current permits are to be more detailed to include a more intensive monitoring mechanism to protect the indigenous flora which is classified into two categories. The first group covers any indigenous vegetation whereas the second deals with, Specially Protected Indigenous Plants which includes cycads, ferns, orchids the raphia palm as well as aloes. Many people have been prosecuted for picking, possession, sale, purchase, transfer or cultivation of the latter group without the relevant permits.