We think of orchids as fluttering flowers to be admired, their unfurling petals watched expectantly by ardent admirers. But they do not sound so exotic when they look like potatoes and are dug up from the earth with a pickaxe, or when they appear in a list of ingredients alongside chillies and peanuts.  Yet this is actually how many people experience orchids.

Chikanda, also known as "kinaka" or "kikanda", is a popular savoury snack in Zambia. It is made by combining orchid tubers, ground peanuts and chillies. The mixture is then cooked to a solid, meatloaf-like consistency. It is estimated that each year over 4.4 million orchid tubers are traded to Zambia from Tanzania, Angola, the Democratic Republic of Congo and Malawi, all to make chikanda.

The trade in chikanda is a threat to the orchids used to make it, because harvesting their tubers kills them. Collectors are now harvesting from ever-larger areas in order to meet the growing demand. But there might be a way to grow the orchids sustainably, so that people can have both their chikanda – and the incomes derived from it – and the beautiful orchids from which it comes.

Tubers, which are roots swollen with carbohydrates, act as energy stores for orchids during dormant seasons. While above ground leaves wither and are shed, below ground the tuber contains the energy of the plant, ready to send up new leaves and flower spikes when conditions are right for growth.

These tubers fuel the life of the plant, but they can also be food for people.

Originally chikanda was consumed by the Bemba tribe in north-east Zambia, and the Nyamwanga, Nyika, Nyiha, Fipa, Lungu and Ndali tribes in southern Tanzania. Being a traditional food, it was harvested on a small scale and consumed locally. Each harvested tuber comes from digging up a wild orchid, most of which belong to the genera Disa, Habenaria and Satyrium.

But now these countries are urbanising. City-dwellers do not collect their own orchids, and for them chikanda is a taste of nostalgia. There is now a long supply chain stretching from rural collectors to city-based traders who in turn sell the tubers to restaurants and snack vendors.

"Mainly middlemen and some transporting business people rely on chikanda as source of income, especially in peak seasons," says Joseph Otieno of Muhimbili University of Health and Allied Sciences in Dar es Salaam, Tanzania. "The rest, including harvesters, only are involved as a supplementary source of income."

In the wild the orchids are easy to tell apart. The loose spikes of green-yellow Satyrium volkensii blend in amongst green foliage, but they are easy to tell apart from the compact bubble-gum pink pops of S. breve flowers. The prominent veins on leaves of S. trinerve are a distinctive feature, and the flame-like flower spikes of Disa erubescens can be spotted from a distance.

But once the tubers are dug up and separated from their plants they are just a jumble of earth-dusted spheres, mostly impossible to tell apart.

Supermarkets and edible orchids might not seem to have much in common, but in both cases barcoding is handy. In supermarkets barcodes are machine-readable patterns based on Universal Product Codes, which allow supermarket scanners to distinguish products. In the mixture of orchids and other plants sold as chikanda, DNA barcoding is a way to identify the different species using their DNA.

Sarina Veldman of Uppsala University, Sweden is working to identify the orchids traded as chikanda.

"We chose DNA barcoding to look at trade in chikanda because it is impossible to determine which species are present at the market by using morphology alone," says Veldman. "There might be up to 81 different species used for chikanda. DNA barcoding is a quick and cost-effective manner of species determination. Moreover, DNA barcoding allows us to look at the species composition of a ready-made chikanda cake and determine which orchids are present, as well as other ingredients and adulterants or contaminants."

In the montane grassland of Kitulo National Park in the Southern Highlands of Tanzania, there are regular flashes of colour from the crimson, pink, yellow, acid green and white orchid flowers. The collection of orchid tubers for chikanda was one of the key triggers for the creation of this park, tropical Africa's first national park for botanical diversity.

The chikanda trade was not the only threat to these orchids. Orchid-rich grasslands are being converted for cultivation of potatoes and pyrethrum, a type of chrysanthemum processed to produce an insecticide, and competition from invasive Patula pine had reduced the area orchids could grow in.

There are indications that wild orchid populations are being depleted by collecting tubers for chikanda.

Market vendors are reporting that tubers are smaller than they used to be. Similarly, Zambia was once self-sufficient in tubers, but now needs imports to meet demand.

I was keen to do what I could to address the threats to these orchids

"If chikanda becomes unavailable at one location, people move on to the next to harvest there instead," says Veldman. "Market vendors report that they are getting fewer supplies from certain areas than in the years before."

Veldman says there are several ways to create a more sustainable trade, but it is not clear which is best.

"One option would be to start a chikanda propagation centre, where chikanda seedlings are propagated and later distributed at a low price," she says. "Another option would be to make the people involved in chikanda more aware of sustainability issues and together think about solutions. Additionally, we could raise awareness about how the chikanda naturally reproduce, and encourage people involved in the harvesting to leave some plants to produce seedpods and help those disperse."

Ruth Bone, while on orchid fieldwork for Royal Botanic Gardens Kew in Zambia, heard about the threat to orchids from the chikanda trade. This prompted her to set up a project on edible wild orchid trade in Zambia.

Chikanda fever will not come to an end

"I was keen to do what I could to address the threats to these orchids, and also concerned for the threat to livelihoods currently based on this ever-diminishing resource, and the safety and security of the harvesters," says Bone. Veldman and Otieno are both involved.

After assessing the wild populations of the orchids used for chikanda, Bone's team is looking at developing knowledge and expertise on propagating the orchids, and establishing a cultivation programme.

Seoljong Kim, a Masters student being supervised by Veldman, conducted a market survey of chikanda in June and July 2016. "Chikanda fever will not come to an end, as it is already a settled local tradition," says Kim.

For now chikanda is on sale everywhere in Zambia, from luxurious hotels to the corners of local markets. Hopefully scientists, conservationists, tuber collectors, and traders will find a way for orchids to arrive on people's plates, while keeping plenty blooming in the grasslands.

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