IT IS the question Catherine Wardrop is constantly asked. In an age of sophisticated digital cameras, why do botanists still need artists to draw plants?

Several times a year Ms Wardrop, one of two illustrators employed by Sydney's Royal Botanic Gardens, is asked to draw a newly discovered species. When it comes to detail and clarity, she says, no camera can match the human eye.

And, she adds, "photographs have to work with what nature has provided". If a leaf, a flower or a stem has the slightest blemish or malformation, the camera records it that way.

Ms Wardrop and her colleague Lesley Elkan bypass nature's flaws by drawing a healthy leaf from a section of one plant, a bud from another, and so on until they have produced a near-perfect composite.

On a sunny Sydney day, being a botanic gardens illustrator may seem the perfect job, but Ms Wardrop spends little time strolling about, admiring blossoms. "Everyone thinks we are outdoors all the time, with butterflies at the end of our pencils," she said.

Instead, she spends much of her day hunched over a microscope, studying glands, hairs on the back of a leaf, or the shape of a stamen. "It can be tedious."

Most of the work is still done by hand, just as Sydney Parkinson did it aboard the Endeavour in 1770.

Whenever the ship's botanists, Joseph Banks and Daniel Solander, returned with another bizarre specimen, it was Parkinson's job to record it.

He did not draw whole plants. There just wasn't time, Ms Wardrop says. "He painted one flower, one leaf, one stem …" When the pictures were returned to England other artists would collate them to recreate the entire specimen.

Parkinson never saw the finished works. "He died on the way home, from malaria. He was only in his 20s," Ms Wardrop said, noting the botanic gardens has 738 original etchings created from his work. "He did an amazing job." While Banks is remembered today, "nobody knows Sydney Parkinson", she said.

When she is not drawing plants, Ms Wardrop is often found sharing her skills with the public, teaching evening classes in botanical illustration, and conducting occasional weekend workshops - a graphite and watercolour seminar is planned for this weekend.

Teaching people to draw and paint plants, she said, helped them discover the hidden world in their own backyards. "Most people don't think to look further than the flowers they see in their garden."

On acquiring the eye of an illustrator they discover how, and why, every plant is different.

Some have evolved tricks to attract the birds they depend upon for pollination. Others use often surprising ploys to lure "bugs, moths, butterflies or tiny little marsupials".

"People get to see that nature is not there for decoration. We get them to understand the story that's going on. It's all about sex."