for National Geographic News
The ghosts of lost plants haunt Mark Olson. As a biologist at the Universidad Nacional Autónoma de México in Mexico City, Olson specializes in plants of the dry tropics. Seasonally dry habitat, which includes forest, savannah, and spiny desert, comprises more than 75 percent of the tropics.
Olson is troubled that more than half of 317 species of neotropical plants described by botanists are known from just one or two collections. Many times, these collections are dated or vague in their descriptions.
"When you know a plant from just one collection, all you know about it is that it exists and where it was found, but we can't say much about it," Olson said. "We don't know if it's very rare and very restricted or if people have just been overlooking it."
Olson's concern is not limited to New World plants. All across the globe, plants that have been found, filed away, and forgotten are his passion. They are what drive him to explore some of the most remoteand dangerousspots on the planet.
"The search for and rediscovery of these species include some of the highlights of my fieldworkand some of the most heartbreakingwhen it becomes clear that a species has probably become extinct," he said.
A Passion for Plants
Growing up near Lake Tahoe in the California town of Grass Valley, Olson was fascinated by the natural world. He knew early on that he wanted to be a biologist.
During a post-high school turtle-tagging expedition to Costa Rica, Olson discovered a love for fieldwork. Less appealing was one collection method for zoological work.
"We put tags on the sea turtles," Olson recalled, "[and the tags] crunched through their flippers. They gasp and wince and bleed all over the place. Obviously it hurts them."
Plant collectinga branch snipped here, a leaf pressed thereseemed less harmful to him, with lower impacts on sensitive populations. Besides, he said, " I thought plants were more interesting." A budding botanist was born.
Olson received his undergraduate degree in botany from the University of California, Santa Barbara, in 1992. After working in the university's herbarium for a year, he spent a year as a Rotary scholar in Italy, learning to draw and exploring the lakes around the northern Italian town of Mantova.
Olson applied to graduate school at Washington University in St. Louis, also home to the world-renowned Missouri Botanical Garden. He earned his Ph.D. in 2001, writing his dissertation on the Moringa family, an assortment of often strange plants that include trees, shrubs, and herbs.
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