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Sifelani Tsiko

Agric, Environment & Innovations Editor

Plants, health and medicine share a long history together. Today, the use of herbal medicine is increasing in Zimbabwe and most other African countries as many people strive to fight the Covid-19 pandemic. In this report, Sifelani Tsiko (ST), Agric, Environment & Innovations speaks to Christopher Chapano (CC), head of the National Herbarium and Botanic Garden, on local plant species and what role the institution plays in providing valuable and useful information on herbal plants.

ST: In brief, what is the role of the National Herbarium and Botanical Gardens?

CC: The National Herbarium and Botanic Garden falls under the Agricultural Research, Innovation and Development in the Ministry of Lands, Agriculture, Water and Rural Resettlement. It is a centre of taxonomic (science of classification of things) research and information on the plants of Zimbabwe and beyond its borders in order to promote their conservation, development and sustainable use. It is responsible for the study of Zimbabwean plants in relation to their identity, names, geographical distribution and uses in order to promote a scientific understanding of how plant diversity can be conserved and utilised sustainably in accordance with national, regional and international management principles that support agricultural productivity and enhance socio-economic development.

ST: What does your day-to-day work involve?

CC: Our work covers a lot of areas at the Herbarium. We conduct research on the flora of Zimbabwe and beyond its borders, conserve dried plant materials and at present, we have more than 500 000 dried plant specimens in our Herbariums. We also keep archival records of the region’s flora covering Botswana, Malawi, Zambia, Caprivi Strip and Mozambique.

The herbarium provides botanical information and diversity stored in a computerised database, plant names, offer support service to the research community — plant identification, information and education, collecting services for bio-prospecting or other specialised projects. Our Botanic Garden conducts research on living plants, does conservation both in-situ and ex-situ, does seed collection and preservation as well as offer recreational facilities to the public.

We also have a nursery where we propagate plants. The Garden comprises plant collections in Zimbabwe, African, systematic section devoted to one or more genera like Acacia, Ficus and Combretaceae. We also have other plant collections covering central and south America, Australia, India and the Far East. The economic section is devoted to plants of economic importance such as coffee, tea, rubber while the Desert House has plants from arid areas of Zimbabwe and Namib desert.

ST: Some herbal plants are toxic and others are not. How can you help the public to distinguish between useful herbs and toxic herbs, for example the Zumbani herb and the Lantana Camara plant which are almost similar?

CC: The National Herbarium and Botanic Garden as I have mentioned above, provides information on plants, we have a rich collection of plants that can provide necessary information required by the public. The information that we provide to the public include: plant identification (provide information on how to properly identify plants), distribution (where they are found), uses (medicine, edible, wild fruits and vegetables, culinary herbs), toxic to both humans and livestock), alien and invasive plants and growing and their conservation status.

ST: Is herbal medicine safe and effective? What is your general comment on this?

CC: In Zimbabwe, herbal medicine has been used by our forefathers for their health before the introduction of conventional medicine. Some of the conventional medicine in use today is coming from plants. It is always good to know the plant that you want to use first before anything else and this information is provided by the National Herbarium and Botanic Garden.

Most of the pharmacy students from tertiary institutions in Zimbabwe get their recommendations on the names of plants they want to use for research from the National Herbarium and Botanic Garden. Herbal medicine to me is effective, I work with plants on a daily basis and I have seen it all. On the safety part of herbal medicine, it is safe for some people and to some they react just like what happens with conventional medicine on other people.

ST: How is herbal medicine different from conventional pharmaceuticals?

CC: A herb is a plant or its part used for its scent, flavour, or therapeutic properties. Any herb may be any part of a plant including its leaves, stem, flowers, roots, and seeds. Herbal products may be raw or commercial preparations used to treat illnesses. Conventional medicine is focused on measurable pathology. Traditional medicine is focused on balanced functioning. This difference in focus brings them to different perspectives on cure.

Conventional cure is tied to a specific diagnosis which is tied to specific pathology, the absence of that pathology is seen as a cure. Herbal medicines each contain a combination of chemicals, as opposed to a single pharmacologically active substance.

ST: Many people, nowadays, cannot distinguish between edible and non-edible wild mushrooms. How can you help the public to understand this better to reduce the consumption of non-edible and toxic mushrooms?

CC: The National Herbarium and Botanic Garden has no specialist in mushrooms.

ST: How can herbal users balance the drug extract ratio and the extraction solvent prepared from fresh herbal plants?

CC: The use of medicinal plants is old as the existence of mankind. According to the World Health Organisation (WHO) data, about 80 percent of world population are using products based on medicinal herbs. Phytotherapy (use of plant-derived medications) is based on the use of herbal drugs and medicinal products for the purpose of prevention and treatment. Rational phytotherapy is a modern concept of herbal medicines use, which are made of standardised herbal extracts.

The quality of each final product is guaranteed by the use of raw materials of a standard quality, defined process of production, and validated equipment. Quality control of herbal drugs and herbal isolates (tinctures, extracts, and essential oils) is done according to the requirements of pharmacopoeia and other relevant regulations. The scope of phyto-preparation quality control depends on its pharmaceutical form.

ST: Which limits are acceptable for the content of active substances of the herbal plant and the shelf life?

CC: This question can best be answered by pharmacists and other clinical specialists in the country.

ST: What guidance is available from the National Herbarium and Botanical Gardens on how to prepare herbal medicines?

CC: We have no guidelines per se, we have literature that has been documented on the toxicity levels of some plant collections we have in the country. A book titled: “The Medicinal and Poisonous Plants of Southern and Eastern Africa by Watt et al, can be useful for the public and researchers.

ST: What is the number of plant collections in Zimbabwe?

CC: Zimbabwe has a total of 5 930 vascular plant taxa (large group of plants) within 1 527 genera and 231 families, according to a study by Mapaura and Timberlake in 2004 and out of these 500 plant taxa have been recorded to be used medicinally.

ST: What are some of the threats to the collections?

CC: There are several factors which are threatening our plant species. These include climate change, changing land use patterns, lack of knowledge about plant importance and conservation and many other human-induced factors.

ST: What is the National Herbarium and Botanical Gardens doing to conserve some of the plant collections in the country?

CC: The National Herbarium and Botanic Garden propagates threatened plant species that are now threatened in the wild like muranga (the pepper-bark tree — Warburgia salutaris), Cycads (Gorongowe), Encephalartos — palm like plant commonly referred to as bread palms and many others. These plants are also conserved in the National Botanic Garden for future generations. The institute also hosts various groups of learners from zero grade to tertiary level of which these groups are also imparted with knowledge on the importance of plant conservation and how to do it.