Truffles are specialised underground mushrooms that can only grow on the roots of particular trees.
There are many different types of truffes across the world. Some are edible, some are not. One of the most prized for the dinner table is the French black truffle (Tuber melanosporum), which grows naturally in the wild in Europe and has now been established in Australia.
Many thousands of years ago truffles likely grew above the ground like a traditional mushroom. But in response to a drying climate they slowly ventured underground and curled up into little balls to conserve moisture.
Traditional mushrooms reproduce when the wind picks up spore from open gills under their mushroom caps and sends it flying to new ground where it germinates and produces a new flush of fungi.
But truffles, being underground, cannot rely on the wind to spread their next generation. Instead, they have evolved a complex aroma that filters up through the soil to entice animals to dig them up and eat them to redistribute their spore.
The aroma of the French black truffle is said to mimic the chemistry of a pig’s sex pheromones! This is why pigs were first used to locate ripe truffles but because they found the truffle scent so irresistible they often ate the truffles before their handlers could pocket them to safety… These days dogs (like the gorgeous Solly pictured) are trained to locate and mark ripe truffles while receiving a non-truffle food reward for their efforts.
Truffles must grow on the roots of oaks or hazelnut trees or they will not survive. The germinating truffle spores send out long filaments that enter the tree roots to form a single root system that is part fungal and part plant. The tree delivers energy to the truffle while the truffle-tree roots explore the soil and gather water and nutrients for the tree. The relationship is symbiotic – meaning both the tree and the truffle benefit from working together.
During spring the truffle-tree roots start to set their subterranean fruit but how they do this remains a scientific mystery. The newly-formed truffles are microscopic and will take an impressive six months to grow and mature. Then, in the chilly days of early June, as the oak and hazelnut trees shed their autumn leaves, the first of the truffles will ripen and release their iconic aroma as they call out to be unearthed …