After 42 years with one of Canberra's best-loved national institutions, that legacy includes one of Australia's biggest collections of botanical line drawings and a vast photographic library of native plants. But it also extends to dozens of small essentials, such as thousands of unobtrusive metal tags that link every plant in the gardens to indexed specimens in the Australian National Herbarium.

''I don't think people realise how much scientific research goes into creating and maintaining a living collection like this,'' he says.

Now one of Australia's best-selling science authors, Mr Fagg came to Canberra in 1970 shortly after graduating from Adelaide University. He was working in Sydney when the job came up, and recalls cramming books, clothes and cameras into his student-era car (''it was a tiny, mad little thing called a Goggomobil'') to make the move. He became the first director of visitor services for the gardens, organising exhibitions, public lectures, science tours for schools, formal receptions for royalty and visiting politicians and ''basically anything considered to be the public face of what goes on here.''

Mr Fagg also helped establish Australia's first online database of photographic records of native plant species, which incorporates more than 48,000 photos, many taken during his plant collecting trips across the continent. And no, he doesn't think digital cameras have necessarily made the task easier.

''I bought my first camera as a kid, and I used to put 20 cents in a jar whenever I took a photo. Film was expensive, processing photos was expensive, so it made me think about the kind of photos I was taking.''

His photographs and drawings appear in 16 books on native plants he's co-authored with fellow botanist John Wrigley.

''John was my boss at the gardens for a while. We got talking about doing a book, and a partnership developed from there. He does the writing, I do the illustrations.''

One of those books, a 700-page dictionary-sized scientific guide to Australian native plants, is being updated for a sixth edition, and has sold more than 200,000 copies, despite its hefty $100 price tag and a title - Australian Native Plants - Cultivation, Use in Landscaping and Propagation - most publicists would probably rate as unsexy.

But the book is considered ''the bible'' of its genre for all gardeners with a passion for native plants. Those sales figures also show there's a healthy appetite among Australia's book-buying public for complex environmental science.

''People are interested in the world around them. And if you respect their desire to learn about the natural world, you don't need to play about with the science to capture their imagination or attention,'' Mr Fagg says.