In remote China, plant hunters seek clues to climate change

Most Mandarin syllables have multiple meanings, so whenever the American ecologist Robbie Hart greets strangers in China, he explains the meaning behind Du, his Chinese name.

“Du as in cuckoo flower,” he says, referring to du juan hua, the Mandarin term for rhododendron.

In 2009, Mr. Hart began traveling to China’s Yunnan Province to study rhododendrons, a flowering plant with famously pretty flowers. About half the world’s roughly 1,000 rhododendron species are native to Yunnan and areas of Nepal, Bhutan, and Myanmar (Burma) – a region that was a favorite destination of 19th and early 20th century American and European explorers who traveled east at the urging of Western botanical curators and green-thumbed aristocrats.

Hart, a graduate student at the Missouri Botanical Garden and the University of Missouri, St. Louis, has inspected more than 10,000 of the explorers’ archived flowers at museums and institutions across Europe and the United States. He is now comparing them with his present-day rhododendron samples. But unlike his footloose predecessors, his aim is to see whether rhododendron behavior during the past century reflects changing global weather patterns.

He is one of a small handful of botanists in the world who study climate change by analyzing how flowering plants are adapting their flowering cycles in response to warming global temperatures. Botanists say such research is important because it draws on little-known historical data to help illuminate the scientific present.

“When these collections were established, no one really thought about climate change research,” says Richard Primack, a professor of biology at Boston University who studies flowering plants in the US and several Asian countries. But today they help scientists “to very consistently demonstrate that climate change is the new reality.”

Chronicle of flowers

It's rewarding to study plant collections in regions where botanists have made a habit of roaming. Mr. Primack, for example, inspects naturalist records that writer Henry David Thoreau kept of Concord, Mass. Scientists Yasuyuki Aono and Keiko Kazui analyze 9th century chronicles of flowering cherry trees in Kyoto, Japan.

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