Not a huge amount is known about fungi but UK scientists believe the organisms could help deal with major environmental challenges like breaking down plastic and finding clean fuel.
Experts from London's Royal Botanic Gardens have been studying fungi and have discovered little is known about the world's three million different species.
Habitat loss, nitrogen pollution and climate change are fungi's major threats which in turn risks the wildlife and natural systems that rely on them, the first State of the World's Fungi study warned.
Only 56 species have had their conservation status assessed for the International Union for Conservation of Nature's Red List of Threatened Species, compared with 25,452 plants and 68,054 animals.
More than 2,000 new species of fungi were found last year, in soil, forests and caves, but new micro-species were also found in diverse places including under fingernails, on a baby carrier and on oil paintings.
Analysis of supermarket bought porcini mushrooms revealed three new species, the experts found.
Fungi is hugely important to life, it grows around roots and helps plants absorb water and nutrients, helping around 90 per cent of the world's plants thrive.
One new species identified in the United Arab Emirates desert may be helping lime, pomegranate and grapes survive the harsh conditions.
But in turn they are also among the most dangerous organisms and can cause ash dieback and honey fungus.
Humans eat around 350 species from truffles to common mushrooms, meat substitutes and blue cheese, as well as products such as beer and bread which need yeast, in a market worth GBP32 billion a year.
They also provide medicines, such as penicillin, statins and immunosuppressant drugs needed for transplants.
The report also found fungi could help with environmental challenges.
A fungus capable of breaking down plastics like polyester polyurethane in weeks rather than years has been found at a rubbish dump in Pakistan, the report said.
Fungi living in plants which can break down molecules in plant cell walls directly into chemicals with similar properties to diesel may also be helpful in producing biofuels.
Director of science at Kew, Professor Kathy Willis, said: "The potential of fungi to address clearly critical problems we have is very strong."
"This report represents the first time the understanding of fungi is brought together in one document.
"This is an incredibly diverse, yet hidden kingdom. Our knowledge of fungi is so small in comparison to plants and animals."
Australian Associated Press