Canna liliifloraOne-fifth of the world's plants - the foundation of life on Earth - are at risk of extinction, a study concludes.
Researchers have sampled almost 4,000 species, and conclude that 22% should be classified as "threatened" - the same alarming rate as for mammals. A further 33% of species were too poorly understood to be assessed. The analysis comes from the Royal Botanic Gardens at Kew, the Natural History Museum and International Union for the Conservation of Nature (IUCN).
There are an estimated 380,000 plant species in all, and many are victims of habitat loss - typically the clearing of forests for agriculture. Species in tropical rainforests are found to be at greatest risk.
The study, known as the Sampled Red List Index for Plants, is an attempt to provide the most accurate assessment so far. Previous studies have focused on the most threatened plants or particular regions.
This one instead sampled species from each of the five main groups of plants, and its authors argue that as a result, their conclusions are more credible.
The report comes ahead of the UN Biodiversity Conference in Nagoya in Japan next month where ministers are due to discuss why conservation targets keep being missed.
Launching the findings, Kew's director, Professor Stephen Hopper, said the study would provide a baseline from which to judge future losses.
"We cannot sit back and watch plant species disappear - plants are the basis of all life on Earth, providing clean air, water, food and fuel.
"Every breath we take involves interacting with plants. They're what we all depend on."
As far as Canna are concerned, we have to treat some of our wild species as being under threat as well. There are no reports of Canna liliiflora being discovered in the wild in the last ten years, and that would be a heart-breaking loss, as it is the only Canna species with genes for white flowers. It is very difficult to grow outside its natural environment and this has created the threat to its existence.