Scott Bailey is a retired Forest Service ecologist, not a detective. But for the last few years he’s been trying to solve a mystery in northern New Hampshire.
The case involves a rare kind of willow tree and one underlying question: Where are all the male plants?
Specifically, Bailey has been inventorying satiny willow trees, also known as Salix pellita. They’re more shrub than tree, native to northern parts of the United States, and shiny. From a distance, if the sun is out, Bailey says they look like headlights.
During his inventories, he couldn’t find any plants with mature fruit or seeds — a sign that something was off. For willows to produce seeds, both a male and a female plant need to be within pollinating distance.
During his inventories, Bailey couldn’t find any plants with male flowers. So he decided this year, he’d inventory all the populations of satiny willows he could find during the flowering season, to see if he could get to the bottom of things.
Out of the nine populations of satiny willows he found, mostly along the upper Connecticut River in Vermont and New Hampshire, only two had male trees, he said: one patch near Colebrook, and a larger group in the Maidstone Bends Preserve near Northumberland.
The satiny willow population in that preserve is the largest he knows of in the region, Bailey said, and could serve as an important source of seeds to keep the plant alive in the region.
Bailey’s observations seem to be the first recorded sightings of male satiny willow trees in New England. He went through records of about 450 specimens going back to the 1800s — not one had male flowers.
Male satiny willows, after they’ve released pollen, drop their flowers quickly, so there’s a short period of time when they can be identified.
“We don’t really know if males have been missing from the region for a long time, or if they’ve just been overlooked because botanists weren’t out at the right time looking.”
Willows can produce asexually, with new trees growing from fragments that break off of a shrub and float away in a flood to root somewhere else. Bailey’s team had a theory that perhaps all the satiny willows in the Connecticut River Valley were created that way, grown from fallen parts of a common ancestor, instead of through pollinated seeds.
But now that he’s found a few male trees, it seems more likely that some trees are reproducing with seeds. That’s a hopeful development, he said.
“We know that we’ve got a potential seed source that can be distributed,” he said. “Without a local seed source, it just seems like with the creep of invasive species and the continued habitat loss, there’s a much greater danger that we would lose the species regionally.”
Bailey took cuttings from male and female plants in the Maidstone Bends Preserve and sent them to a U.S. Department of Agriculture lab in Iowa, where there’s a seed bank for willows. Scientists there will grow the cuttings, pollinate them, and save the seeds they produce.
“Should the need or an opportunity arise to reintroduce this plant into the region, we will have a local source of seeds that’s saved and available,” he said.
But the case isn’t closed yet. Scientists don’t know why the male trees are so scarce. And there’s at least one other rare willow facing the same problem: the Labrador willow.
The only place that plant is found in the country is above treeline on Mount Washington. Bailey says his team’s surveys show that less than five percent of the population there are males.
“This is a puzzle,” he said.
He’s hoping more research can get to the root of things.
