Case Studies

Desert truffles
- Australia and the Kalahari

Truffles are found in the dry lands of all the world's continents except Antarctica. The truffles found in such areas, often collectively called desert truffles, are not the same as the well-known gourmet truffles of Europe. Nevertheless they are eaten by various peoples. The two papers listed at the end of this page give summaries of what is known about the desert truffles of Australia and the Kalahari and this page is based on parts of those papers.

The first non-Aboriginal collected specimen of an Australian desert truffle was found in the Great Victorian Desert (western South Australia) on June 25 1891 by Richard Helms, a member of the Elder Scientific Exploration Expedition. That specimen belongs to a species now known as Elderia arenivaga (once known as Choiromyces aboriginum) and mature fruiting bodies range from 4 to 8 centimetres in diameter. Since that initial collection this species has been found in the Eastern Great Sandy Desert ( Western Australia), the Tanami Desert ( Northern Territory) and the Simpson Desert ( South Australia). In addition to this species the first paper listed in the references gives descriptions of the six other truffles known from central Australia - Horakiella watarrkana, Mattirolomyces mulpu, Mycoclelandia arenacea, Mycoclelandia bulundari, Reddellomyces westraliensis and Ulurua nonparaphysata. In size the mature specimens range from 2 to 9 centimetres in diameter, The authors note that six of those seven species are so far known only from desert areas whereas the Reddellomyces, which has been found in a swale near Alice Springs, is also widely distributed in the eucalypt forests of southern Australia and so might be looked at as not a "true" desert truffle.

In the Kalahari the species Kalaharituber pfeilii (once known as Terfezia pfeilii) is by far the best known and is sometimes referred to as the Kalahari truffle. Eremiomyces echinulatus is the only other truffle known from the Kalahari and both it and the Kalaharituber are also known from elsewhere in southern Africa. The authors of the second paper listed below also note Mattirolomyces austroafricanus, not yet found from the Kalahari but known from arid savannah in South Africa. The mature Kalaharituber truffles are up to 12 centimetres in diameter. Fruiting bodies generally weigh under 200 grams but the second paper listed below mentions 400 and 500 gram Kalaharituber truffles, with the comment that the large size of the latter was due to very good rains.

Of the three southern African species listed above only Kalaharituber pfeilii is in widespread use. The other two appear to be very rarely found and the authors of the second paper found no evidence of their being used for food, but thought they would quite likely be eaten when found. Of the Australian species at least two, namely Elderia arenivaga and Mycoclelandia bulundari, are widespread through central Australia and are known to have been widely used.

Both the Australian and Kalahari truffles can develop and mature rather quickly after good, soil-wetting rain. Unfortunately there have been no detailed studies of the correlations between rainfall patterns and truffle fruiting in either arid Australia or the Kalahari. Long-term records from weather stations in the Kalahari show an erratic rainfall, varying both between years and between areas of the Kalahari, but the heaviest falls are generally between November and April. In different parts of the Kalahari truffles have been found from April through to July and in Australia the information recorded on the relatively few herbarium collections shows that they can appear from April through to September. In both places the thin-walled cells in the immature fruiting bodies take up large amounts of water, The water held by these swollen cells probably provides the moisture needed for spore formation and the uptake of water also causes the fruiting bodies to swell and so produce tell-tale cracks in the overlying soil surface. Of course all cracks are not equal, since not all need be produced by truffles. In the Pitjantjatjara language of Australia witita, a word for truffle, is related to wititata, the grey shrike thrush (Colluricincla harmonica), it being said that the call of the bird after rain makes the truffle grow. In many parts of the world people have long observed that certain natural phenomena are linked and so traditional lore along the lines of "when the So-and-so bird calls we know that the Such-and such bush will be in fruit" has arisen. In this way you know when it is worth your while to go looking for the Such-and-such fruit. So, in central Australia, presumably the same level of rain that promotes truffle formation would also induce the shrike thrush to call more readily. By paying attention to the shrike thrush calls, the Pitjantjatjara people would avoid digging at cracks when such an activity would be largely pointless.

Once the overlying surface has been cracked, those cracks would be enlarged further by the wind's erosive action and in this way the truffles are eventually exposed to the air. The inflated, thin-walled cells dry out and collapse and the dry truffles are then abraded by wind-borne sand and the spores within the truffles can then be carried away by such winds. It is well-known that truffle spores in temperate areas are often spread by animals that are drawn to eat the truffles. In those cases the spores may be deposited in the animals' faeces but also via fragments left behind after some truffle munching. What role animals play in desert truffle spore dispersal is not known but it seems likely that they would at least sometimes help in spore dispersal. In the Kalahari hyenas (Hyaena brunnea), baboons (Papio ursinus), bat-eared foxes (Otocyon megalotis) and meerkats (Suricata suricata) have been seen digging up and eating truffles. In Australia there have been no reports of native animals eating desert truffles. However this is undoubtedly simply an absence of sighting rather than an absence of eating. The Australian fauna includes a good number of mycophagists and a number of those animals are found in the same areas as the desert truffles.

While the field notes associated with various herbarium collections of Australian desert truffles mention a variety of plants growing near the truffles, there has not yet been any research into establishing with which plants the Australian desert truffles form mycorrhizas. Research into the mycorrhizal partners of Kalaharituber pfeilii has produced evidence of its ability to form mycorrhizas with a variety of monocotyledonous and dicotyledonous plants. However, the strength of the evidence is variable and for some possible plant partners the evidence can be considered only as suggestive. On the other hand, for some plants the evidence is very strong. For example DNA extracted from fungal hyphae colonizing roots of tsamma (Citrullus lanatus) has been found to match DNA from Kalaharituber pfeilii truffles. Tsamma, native to southern Africa, is the wild ancestor of today's cultivated watermelon and is common in the Kalahari. Given the present state of knowledge it's clear that further research is necessary before we can be sure of the range of this truffle's mycorrhizal partners.

In both the Kalahari and in Australia there is undoubtedly a very long history of desert truffle usage by the indigenous peoples. What of the present and the future? The authors of the first paper write that...

Desert truffles of the Australian Outback, once a cherished food resource for diverse Aboriginal ethnic groups, currently have little or no value for contemporary Aboriginal communities either as gathered food or as a saleable or even tradeable commodity...Little is known about their biology...while Aboriginal usage and knowledge has been only sketchily recorded. Traditional knowledge is increasingly endangered as the elders succumb one by one.

By contrast, the authors of the second paper note that...

Unlike the situation of rapidly declining traditional knowledge and use of desert truffles in Australia...the Khoisan of the Kalahari continue to use and to value the Kalahari truffle. However, truffle production appears to be declining, at least where livestock are concentrated...some land use practices introduced by Europeans may conflict with Kalahari truffle production, especially on fragile sandy soils

They go on to say that there is already considerable commercial harvesting of Kalahari truffles. However there is still much more that needs to be learned to ensure that the Kalahari truffle industry is sustainable and the authors emphasize that equally important is attention to the interests of the indigenous inhabitants.

References

Trappe, JM; Claridge, AW; Claridge, DL & Liddle, L. (2008). Desert truffles of the Australian Outback: Ecology, Ethnomycology, and Taxonomy. Economic Botany, 62, 497-506.

Trappe, JM; Claridge, AW; Arora, D & Smit, WA. (2008). Desert truffles of the African Kalahari: Ecology, Ethnomycology, and Taxonomy. Economic Botany, 62, 521-529.