Spilanthol is so potent, in fact, that jambu is also used for medicinal purposes, hence one of its English aliases: "toothache plant". Indigenous people have used jambu to treat mouth ulcers and dental problems for centuries.

Until recently, the herb was almost unknown outside of Brazil's Amazon region, where it is a feature of traditional dishes like tacacá, a sour prawn broth in which jambu highlights the sharp, savoury notes of wild cassava roots. Now, buoyed by a wider, growing interest in Brazilian ingredients and products, jambu is beginning to make its way from an obscure regional staple to a national symbol of Brazilian biodiversity. The main push behind this is the recent trend of combining the electric herb with cachaça, a sugarcane spirit that is synonymous with Brazilian culture.

"When people started using jambu I thought, 'wow, about time'," said Néli Pereira, a São Paulo-based mixologist who has known about jambu for longer than most. "Of course, in Belém they have been using it forever," she continued, referring to the capital of Pará, a state in the north of Brazil through which the lower Amazon river flows to the sea.

Pereira first tasted jambu at a Dona Onete concert in 2014. The Brazilian singer and cultural icon from Pará has a famous song about jambu that includes a deliciously rhythmic repetition of the word "treme", meaning "it trembles". It was during this song that concert organisers started spraying cachaça jambu into the mouths of willing spectators.

Not only does jambu accentuate the fiery notes of the alcohol, but its numbing properties make jambu cachaça "interesting to kiss with", according to Pereira. It is, in other words, the perfect party drink. "Jambu is everything," she said, "It's pop, it's traditional, it's gastronomy, but it's also playful – there's a whole vibe to it."

Leodoro Porto, proprietor of Meu Garoto bar in Belém, is credited with creating the first jambu-infused cachaça back in 2011. While Pereira was an early adopter, incorporating it into cocktail creations after her 2014 concert experience, it was only around 2018 that jambu cachaça brands started cropping up outside of Pará, introducing the herb to a national audience.

"The last few years have made a lot of difference to jambu," said Rodrigo França, co-founder of São Paulo-based drinks brand Jós Brasil, one of the first cachaça jambu producers outside of Pará.

França and his three co-founders first stumbled upon jambu cachaça in late 2017 while on holiday in Alter do Chão, a freshwater resort town in Pará. "It was the only bar open and the only drink they had," França said. The friends knew nothing about jambu and were blown away by their first collective encounter with its "trembling" effect.

Failing to find the spirit back home in São Paulo – the world's fourth largest city where just about everything is usually available – they started making their own jambu cachaça at a distillery in the state of São Paulo. However, they were surprised people knew so little about such a quintessentially Brazilian product. "How come something can be a cultural phenomenon in the north of Brazil, but unknown in São Paulo?" França asked. "We know so much about products from other countries, but not about those that are truly Brazilian."

Jambu's recent popularity is intimately entwined with a wider, growing interest in Brazilian ingredients and cultural identity.

"We learned from abroad what is good and what's not," said Felipe Jannuzzi, founder of BR ME, an online store that specialises in Brazilian ingredients. Jannuzzi continued, "What was cool was what was foreign, but the younger generation is finding a new cool – we are learning how to appreciate our own culture."

When I met him recently at his offices in downtown São Paulo, Jannuzzi excitedly gathered Brazilian coffee, olive oils and botanicals to show me. Next, he poured me a gin he created using a spice called pacová, an indigenous equivalent to cardamom. "You can ask anybody here about it – no one will have heard of it," he said. "We used to use pacová here in Brazil but it was replaced by cardamom from abroad, so I created this gin as a way to talk about Brazilian tradition and diversity."

Brazil is the world's biodiversity champion. It is home to more species of plant than anywhere else on the planet, and several incredibly important ecosystems. The Amazon is the rock star, but there is also the Atlantic Forest, which stretches along the coast of Brazil; the Cerrado, a vast tropical savannah twice the size of Egypt; and the Pantanal, the world's largest tropical wetland area. These ecosystems are home to countless unique species of plants, many of which are edible.

Sabor De Fazenda, a plant nursery in the north of São Paulo, grows a number of these obscure, edible plants, or what are referred to in Brazil as PANCs – an acronym in Portuguese for "non-conventional edible plants".

First coined in 2007 by biologist Valdely Kinupp, PANC has since evolved into a nationwide movement that seeks to elevate the hundreds of species of edible plants that have been squeezed from our diets by industrialised food habits.

When I visited Sabor De Fazenda, Barbara Cordovani, a specialist in edible botanicals, showed me a few stars of the PANC movement that I recognised from menus at trendy restaurants, such as ora-pro-nóbis, a dark green leaf that has earned the moniker "poor man's meat" due to its incredibly high protein content.

"In Brazilian food, we use aromatic herbs, mostly from the Mediterranean, but we have so many native plants with similar aromas," Cordovani said.

One example of these substitutes is alfavaca anis. The herb is a favourite of Clarissa Taguchi, founder of PANCS Brasil and another specialist in native Brazilian ingredients. Indigenous to the Atlantic Forest and a relative of basil, alfavaca anis has a more complex, liquorice-like flavour reminiscent of star anise. "I've fallen in love with many other PANCs since," Taguchi said, "But this was my first."

By substituting native plants for imported ingredients, PANC proponents hope to protect Brazilian biodiversity by celebrating it. Cardovani and Taguchi both credit Brazilians' growing environmental awareness for the current popularity of PANCs. "People are realising how much food production impacts biodiversity and the environment," Taguchi told me, "so they are sourcing locally."

Jambu is only one of countless Brazilian ingredients coming to the fore, but with its signature numbing effect and good-time reputation, it makes a fantastic ambassador for Brazil's biodiversity.

"It's thrilling," Jannuzzi said. "It's a big challenge, but a big opportunity too." Pereira shares his optimism. "This movement has started gaining momentum and I don't think it's a trend," she said, "it's something that is here to stay."

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