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Monday, June 01, 2020

Down in Jungleland: Fascinating Fungi

A foray into the kingdom of recyclers and decomposers.

Written by Ranjit Lal | Updated: March 17, 2019 6:30:33 am
A plant fungus has the most fascinating relationship with the root system of trees. (Source: Ranjit Lal)

Walk along a forest trail on a dim, cloudy morning, after perhaps a night of rain, and you may suddenly be brought up short, your gaze fixed at the base of a great gnarled tree or stump, or chocolate dark bough: you walked this way yesterday and there was nothing. Now, crouched around the massive trunk, is a secretive huddle of toadstools or mushrooms, beige, bright orange or deadly red; or else, as if nailed to a branch, a huge shelf-like structure, caramel brown. Mushrooms and toadstools have a way of appearing out of thin air as it were. But what you see so briefly is the tip of the iceberg. These are just the short-lived fruiting bodies of members of the third great kingdom of living creatures on earth: fungi which comprise mold, rust, and yeast.

No, they are not a part of the plant kingdom, and certainly not of the animal. For unlike plants, they do not produce their own food, but reach out with fine tentacles and secrete digestive enzymes on their food source, liquidising and only then absorbing it. Fungi have their own giant kingdom, comprising over 144,000 species that scientists know of, and perhaps 2.8 to 3.8 million in all. And they are vital to the well-being of the planet. Fungi, along with bacteria, are great recyclers and decomposers, subsisting on living and decaying organic matter and converting it back into useable inorganic elements, like carbon, nitrogen and phosphorous. They are into nutrient recycling on a massive scale: That apart, we’ve used fungi as a food source, either directly (as sautéed mushrooms on toast) or indirectly, in the making of wine, beer, soy sauce and blue cheeses. The leavening of our “dubble roti” is also due to fungi — a baker’s yeast in this case.

Perhaps, their greatest contribution has been in the medical field. In 1928, Alexander Fleming noticed that green mold Penicillium notatum, a kind of fungi, growing in a culture dish, tended to keep Staphylococcus bacteria in the same dish at arm’s length. Fleming isolated the substance in the mold that stopped the bacterial growth and announced the development of the world’s first antibiotic — penicillin — in 1929.

But fungi — mushrooms, for example — can also be highly poisonous, and possess mind-altering substances. LSD is one such drug extracted from a mushroom. You may want to pick a basketful of wild mushrooms for lunch, but for heaven’s sake, do not ever consume them. Only trained experts can tell the difference between safe and poisonous mushrooms — and mushroom poisoning can be a singularly (and sometimes terminally) unpleasant experience.

Most fungi grow filamentously from their spores, sending out very fine tendrils (hyphae), several centimeters long, from their tips and branching out, often forming a network called mycelium. These are able to take in nutrients from their living hosts, such as mold does while growing on a piece of fruit. Fungi may reproduce sexually or asexually, and spores (which form by the billion) are ejected sometimes forcibly by the mushroom, and more usually by the wind. Their relationship with members of the plant and animal kingdom are often symbiotic — either mutualistic (benefiting both) or antagonistic.

A plant fungus has the most fascinating relationship with the root system of trees. This relationship is called mycorrhizal association and 90 per cent of all plants are involved in such a relationship with fungi. The tendrils of the fungi attach themselves to the ends of roots, and extend further, forming an extensive mesh, seeking out water and inorganic compounds which the plant may need, especially in places where there is a shortage of these. In exchange, the plant provides nutrients, like carbohydrates, needed by the fungus. This network may spread over many hundreds of acres — and even enable trees to “communicate” with each other and help them “exchange” nutrients and “information”.

There are some fungi that are parasites and kill their hosts. Some 300 species have been found to be inimical to our well-being, and some of these “mycotoxins” can be lethal, like Aramita mushrooms, and the molds that spoil foodstuffs. Fungi’s main victims are plants. The potato blight, a fungus, led to mass starvation amongst the Irish in the 19th century and another fungus which attacked grapes nearly destroyed the French wine industry.

But, yes, they can be wonderful too: truffles, a kind of mushroom found underground in countries like France, are sniffed out by trained truffle hounds and pigs for our consumption. They fetch incredible prices and are stuffed into omelettes. Mushrooms and other kinds of fungi, if they are good, they are very, very good, but when they are bad, they are horrid.

Ranjit Lal is an author, environmentalist and bird watcher.

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