So it was with some consternation that the local field botanist found two of her favorite early flowers — sprigs of white and purple “harbinger of spring” no higher than an inch and graceful white twinleaf — in full bloom in the chill of late March.
Fleming was expecting to see some “spring beauty,” one of the earliest bloomers of the area, and perhaps a few of the weedier species. But she found, among others, “Dutchman’s breeches,” the funny little white flower that looks like long underwear hanging upside down, and cut-leaved toothwort.
“I was surprised to see that,” she said. “That’s something I would have expected two weeks later.”
Bloom hunters like Fleming, who for 40 years have been tramping through the woods, roaming along riverbanks and scrambling over rocky outcrops to document the first blooms of spring in the Washington area, worry that what they have been seeing is nothing less than the slow, inexorable shift of global warming.
They even have a name for it: season creep. And it’s happening all over the world.
For 1,000 years, the Koreans have recorded the first cherry blossoms of spring, so central is that flower to their cultural identity. For 300 years, Europeans have meticulously tracked when grapevines bloom to time planting and harvest. On both continents, botanists are finding earlier and earlier blooming.
In Washington, chronicling blooms began as sort of a rite of spring for botanists and amateur flower lovers eager to see the first signs of life after a long, barren winter. Initially, they wrote down their findings for more than 600 species in an enormous log book at the Smithsonian Institution’s National Herbarium year after year.
But over time, they began to notice the native blooms coming earlier and earlier. In a 2005 analysis of 100 of the most popular flowers they hunted, Smithsonian botanists found that 90 species bloomed two to 44 days earlier than they had 20 years ago; only 10 species, on average, bloomed later. Even the famous cherry blossoms along the Tidal Basin, they found, were blooming six to nine days earlier than they had in the 1970s.
“There is always variation from year-to-year in nature. And I don’t want to sound alarmist that spring is coming earlier and earlier,” said Fleming, who is in her 70s. “But, boy, every year, we do feel it.”
Botanists poring over the Asian and European blooming records, the Smithsonian log, and the accounts of American observers such as Henry David Thoreau and explorers Meriwether Lewis and William Clark, are finding the same phenomenon.
“When you gather together all the scientific studies that have documented this, we can see that about 80 percent of the species are changing earlier in the spring,” said Jake Weltzin, an ecologist with the U.S. Geological Survey.