Fungus & Mushrooms: An Introduction to Zimbabwean Species

Cathy Sharp is our leading guide on the very rich population of mushrooms in Zimbabwe. Here I borrow from her A Pocket Guide to Mushrooms in Zimbabwe Volume 1: Some Common Species. She begins this book with the stern warning. “The author is NOT responsible for any sickness, death or misfortune suffered by any person resulting from eating a mushroom described in this book.”

Fungi are more commonly called mushrooms, and some we like to eat and some we know are deadly poisonous. In fact the mushrooms we see are only a small part of the mushroom world. Think of the apples on an apple tree but with the apples on the ground and the tree beneath the ground. The mushrooms are the fruits (spreading spore and not seeds) and the ‘tree’ beneath the surface is a mass of living threads that attach themselves to tree roots, to the benefit of themselves and the tree. These networks of threads (or hyphae) within the soil are called mycorrhiza.  

Mycorrhizal fungi help plant roots take up nitrogen, phosphates and other nutrients and in return the plant supplies the fungus with sugars produced by photosynthesis in the leaves. That mutually beneficial relationship is called symbiosis.

Termite fungi have a special symbiotic partnership with termites where one cannot live without the other. Certain termites actively cultivate the fungus in a ‘garden’ whose walls are made of lignin and cellulose, compounds which cannot be eaten by the termite. The fungus breaks down these compounds making them available as food for worker termites.

Different from a symbiotic partnership is a parasite.      

Parasitic fungi are those infecting living plants (e.g., rusts and mildews on agricultural crops, and some bracket fungi) and animals (e.g., fungi that cause thrush, ringworm. Athlete’s foot, and bat-cave disease).

Other fungi, saprophytic fungi,  utilize dead matter as their source of nutrition and are thus essential in recycling carbon. They are responsible for wood decay and overall decomposition of plant litter e.g., mushrooms, bracket fungi and dung fungi. By infecting dead wood, plant debris, animal dung and other carbon- based materials they make sugars that can be ‘eaten’ by the fungi and nearby plants.

Most fungi use wind to disperse their spores. Stinkhorns take advantage of their disgusting smell to attract flies and other insects which either eat the spore-mass and so disperse the spores through their faeces or carry the spores on their bodies and disperse spores that way. The ‘truffle’ matifi (Karanga) smells of ripe peaches and this is surely to attract duiker and other small animals, which find the truffle just beneath the surface by scuffing them out of the litter.

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Miombo woodland is characterized by having many mycorrhizal trees, Brachystegia and Afzelia, and Monotes are examples, and during the rainy season their fungi produce a vast array of colourful mushrooms (e.g., Cantharellus, Lactarius, Russula and boletes or ‘sponge fungi’).

For the rest of the year these fungi exist as mycellum beneath the surface.

Bio-luminescent fungi that glow in the dark are found in the montane forests of eastern Zimbabwe. Their light is a by-product of chemical processes within the mushroom and within the decaying substrate. This light may have an ecological advantage in attracting nocturnal insects which then disperse the mushroom’s spores.

The largest fungus found in Zimbabwe to date is a bracket fungus (Lenziles elegans) measuring almost 1.6 metres across.

Zimbabwe’s largest gilled fungus is Termitomyces  titanicus , known as makhowa in Shona or ikhowa elimhlope in Ndebele.  According to the Guinness Book of Records this is the largest mushroom in the world. It has a cap up to one metre across and weighs several kilograms.

The largest tubed fungus (bolete) in this country is Phlebopus colossus which is called dindini mupfura in Karanga, which can weigh up to 2.5kg and measures more than 35cm in diameter.

The smallest macrofungi are the Myxomycetes (slime moulds).

– Robin Wild –

Slime moulds are a fascinating life form in themselves. Look at this video of a TED talk by Heather Barnett about them.