These waning March days, the trails are still coated in ice and snow at the Middlesex Fells, a sprawling reservation of woods and water just north of Boston. Around Spot Pond, the branches are bare on the beeches and alders, the dark green of pines the only vivid color in the gray-brown palette of early spring.

It's a scene that has changed little in more than 100 years — but may change dramatically in the coming half-century.

If global climate change continues unabated, in 50 years "One could posit that Massachusetts would look an awful lot like Georgia or even northern Florida," says Elizabeth Farnsworth, senior research ecologist at the New England Wild Flower Society.

Which would mean, for a spot like Spot Pond, that "If we were standing out here in mid-late March, we might actually expect to see a lot of these species flowering already. We’re already seeing changes in the flowering times of a number of species. They’re flowering two weeks earlier in the year than they used to 50 years ago."

Farnsworth is the author of "State of the Plants," a new report that the New England Wild Flower Society calls the most thorough ever compiled on the status of the region's plant life.

It finds that New England is home to nearly 600 rare or endangered native plant species, about a fifth of all its species. And among the threats that New England plants face is climate change: If current trends continue, the report notes, in 50 years, Vermont will have the climate of current-day North Carolina.

How would that alter the New England plant landscape? In myriad ways, but consider just the colorful sugar maples that are the region's iconic trees. Farnsworth says they could be forced northward, because they can’t tolerate higher temperatures.

"In a higher emission scenario, which is also possible if greenhouse gas emissions just continue to rise, maples could be restricted to northern Maine," she says.

Already, climate change has begun to leave its mark on the region's flora.

New England Wild Flower Society senior research ecologist Elizabeth Farnsworth and Bryan Hamlin, chair of The Friends of the Fells, near Spot Pond in the Middlesex Fells Reservation (Carey Goldberg/WBUR)

Bryan Hamlin, board chair of the The Friends of the Fells, knows the botany of these woods intimately, and says he’s witnessed two big shifts in recent years.

"Some species that don’t like it too warm have moved north. Other species are coming up from Connecticut. So that's one thing we're noticing," he says. "The other thing that comes, because it’s climate change, not just warming: As we have seen in the last month, precipitation has increased, something like 10 percent in the last 30 years." And meanwhile, the forest has matured. "So any plants that like it dark and damp, they have flourished."

Hamlin has seen subtler changes as well, with connections to climate change that are likely but not as clear: "We’re losing orchids. Just in the 12 years I’ve been walking these woods, I’ve seen the orchids really retreat. We’ve lost two or three species just in the last few years."

Also, the hemlocks of the Fells are under attack by woolly adelgids, pests that the warmer climate has prompted to move north. "The hemlocks are dying here in the Fells," Hamlin says.

And concern is mounting about another pest, the emerald ash borer, that attacks ash trees and has recently appeared in Massachusetts and New Hampshire, Farnsworth says.

Climate effects can even be seen in the earlier blooming times and faster withering of the region's fragrant and much-beloved lilacs, Farnsworth notes. And old photographs from 100 years ago show that deciduous trees had not yet unfurled their leaves by Memorial Day, Hamlin says, while trees today "leaf-out" by earlier in May.