As his experience with plants grew, in the 1990s, Gan started to view existing information about his hometown with a critical eye.

"It just didn't feel right to read in all introduction materials that Zhuxi county has only about 900 plant species," Gan says.

Following a surgery and his retirement from work in 1999, he decided to get to the bottom of it.

After recuperating, he started off his journey of plant studies at Shibalichangxia in 2001.

He prepared food and drove an old jeep into the valley. Whenever he found a plant he hadn't seen before, he took pictures and samples of it, while noting its features.

He was often exposed to danger, especially in the beginning. He had several close calls in his jeep as he maneuvered it along the perilous mountain paths.

Over the following four years, Gan left his footprints over all of Shibalichangxia nature reserve and produced nearly 10,000 photos and several reams of notes. To ascertain plant distribution and mutation, Gan dug into his own pocket and visited experts from Beijing, Wuhan in Hubei province, and Kunming in Yunnan province.

At first, experts taught him how to make standard specimens after seeing that some of his samples were as big as a newspaper page.

They reminded Gan of what standard samples should look like, and that it's better to merely accentuate key features rather than the whole plant. "Then I realized herbal plants need roots, while the woody ones should have blossoms and fruits when making a sample," he says.

Gan's commitment has made him friends with many scholars and experts in botanical circles. They have helped Gan refer to the documents and identify the plants he brought in.

In 2005, Gan finished his first magnum opus Flora of Zhuxi, which includes colorful images, characteristics, geographic distribution and the economic value of more than 2,200 plants in the county.

The published tome caused a sensation in the field. Guo Youhao, a botanist and professor from Wuhan University, says: "It's no easy job surveying plant resources and categorizing them.

"It's completely beyond my expectations that the Flora of Zhuxi is such a good job."

In 2006, Gan's book won the second provincial science and technology prize in Hubei. Yet, Gan didn't plan to rest on his laurels.