Seven years' work, more than 100,000 four-wheel-drive kilometres and countless hours walking in dense forest have paid off for a pair of Wellington writers.

New Zealand's Native Trees, by botanist John Dawson and photographer Rob Lucas, was crowned New Zealand Post Book of the Year at a gala dinner in Auckland.

Most of the book's 2300 photographs were taken by Lucas during visits to some of the country's most inaccessible areas.

It features more than 320 species of native flora from the monstrous kauri and ubiquitous cabbage tree to rare species found only on offshore islands.

Judges' convenor Chris Bourke said the book, which also won the illustrated non-fiction category, would affect generations to come.

“From the detailed and authoritative research, accessible and comprehensive writing, detailed yet expansive photography, near flawless editing, design and layout, this is a quality book from start to finish.”

Mr Dawson said the book had been a group effort and they had been quietly confident of taking out the award.

It had garnered good reviews and the difficult part for him had been to replace the normal botanical language with everyday words that would not bore people, he said.

"If it was just a list of species and characteristics it wouldn't be interesting but it has all sorts of interesting stories."

The pair have previously collaborated on books including Nature Guide to the New Zealand Forest.

Dawson was associate professor of botany at Victoria University until his retirement in 1988.

Since then he has been undertaking botanical research in New Caledonia, teaching courses on native plants, guiding groups around the Otari Native Botanic Garden and writing books.

Lucas lectured in horticulture at the Open Polytechnic until his retirement in 2006. His photographs of plants have been widely published, and he is the author and co-author of several books.

Wellington historian and novelist Joan Druett won the general non-fiction category for Tupaia: The Remarkable Story of Captain Cook's Polynesian Navigator.

The book of the year winners receive $15,000. The Maori language award winner and the winners of the four category awards each receive $10,000, and the people's choice winner gets $5000.

THE WINNERS

New Zealand Post Book of the Year: New Zealand’s Native Trees, John Dawson and Rob Lucas

Fiction: Rangatira, Paula Morris

Poetry: Shift, Rhian Gallagher

General non-fiction: Tupaia: The Remarkable Story of Captain Cook’s Polynesian Navigator, Joan Druett

Illustrated non-fiction: New Zealand’s Native Trees, John Dawson and Rob Lucas

Maori language award: Toku Reo, Toku Ohooho: My Language, My Inspiration, Chris Winitana

People’s Choice: From Under the Overcoat, Sue Orr

- © Fairfax NZ News