Western Australia's Herbarium is the state's permanent plant library and is constantly adding new species to its records.

"It never ceases to be exciting," Rob Davis, an identification botanist at the facility in Perth, said of discovering and naming previously unknown wildflowers.

The Herbarium, which is part of the state's Department of Parks and Wildlife, is devoted to keeping records of the thousands of species of flora that are native to Western Australia.

"It's a part of the Herbarium's charter to actually catalogue the flora," Mr Davis told 720 ABC Perth.

"It's in an act of Parliament, and it's about identifying our diversity.

"Our plants are collected in the bush and then pressed and dried and we document their habitats and flower colours and then they are locked away."

A pressed plant at the WA Herbarium ( Supplied: Juliet Wege, Western Australian Herbarium )

Despite having already recorded more than 12,000 species, Herbarium staff and the general public discover on average around 50 more each year.

No nine-to-five job

Mr Davis is passionate about his work, which is much more than a nine-to-five job — his most recent discovery was made while he was on holiday in the South West.

"Recently we discovered a new species in the Northcliffe area after the Northcliffe fires," he said.

"I was just on a couple of days off, I went down with a mate to look at orchids and I kicked off a hydrocotyle, which it turned out was a fire ephemeral — it has come up out of the fire."

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The small plant he discovered could only be found in a one-square-kilometre area and has since disappeared.

All the same, finding something new was an "extraordinary feeling", he said.

"That's a real lightbulb moment, you just feel like breakdancing down the track."

Other discoveries come from the general public who spot something unusual and get in touch with the Herbarium.

Pastoralist discovers new waterlily

One such find was made recently by a pastoralist in the Pilbara who sent the Herbarium pictures of what turned out to be a new waterlily.

"Cathy Walsh from Lyndon sent me an image to identify," Mr Davis said.

"I thought: 'Wow, what on Earth is this thing?'

"It was sitting in ponds at the end of a small river system and we didn't recognise it.

"Cathy put a couple of pieces in a bucket and brought it down to us and through that we could get a closer look and discovered it was a new species."

In recognition of her work, Mr Davis said the lily was soon to be named after Cathy Walsh.