Did you know that the Arnold Arboretum is home to some 16,000 specimen plants cared for by only four arborists? Or that the Dawn Redwood, the emblem of this “living museum,” is considered to be a living fossil, once thought to be extinct? (The arb is home to some 200 of these beauties.)

On a Saturday in late October, NESW members learned these facts and much more in a great tour led by Brad McGrath, a docent at the arb.

“We had a gorgeous fall day and a very enthusiastic, knowledgeable guide. About a dozen of us strolled past many kinds of trees and learned a lot about what does well in what conditions, and the history of the arboretum,” said Richard Saltus, a senior science writer at the Dana-Farber Cancer Institute.

Among those trees and shrubs: an Amur Cork Tree that was a gift from the czar of Russia; the Paperbark Maple, a favorite of many arb employees, including Brad; and the oldest documented Franklinia, otherwise known as the Ben Franklin tree (it was named after Franklin, who according to Wikipedia was a great friend of the discoverer’s father).

Brad also shared many great tips about growing trees and learning more about them. For example, he noted that you don’t have to plant large, older trees; smaller, younger ones will quickly catch up in height and vigor.

If you’d like to learn more about a specific plant, make sure to check out the information on its metal tag. Also consult the Arboretum Explorer, an interactive map that can be accessed from your laptop or your phone’s browser. Type in the plant’s ID number or name, and you can find its exact location in the arb, when it was planted, growing conditions, and much more.

NESW plans to offer this tour again, perhaps twice a year to take advantage of the seasons. Watch the NESW listserv or our Facebook page for updates.

–Elizabeth Thomson

Along the Niobrara River in Northern Nebraska lives a grove of aspens that until recently posed a mystery to plant biologists including Jake Grossman, a Putnam Fellow at the Arnold Arboretum in Jamaica Plain, Mass.

Grossman described that mystery and how he helped solve it at the NESW’s latest “Pizza with a Scientist” event on January 15.

Quaking or Bigtooth?

The conundrum? The Niobrara trees don’t look like quaking aspens, the only species that lives anywhere close by. Locals — including Buffalo Bruce MacIntosh, an environmentalist and aspen aficionado — believed they were hybrids, or a cross between quaking aspens and bigtooth aspens. But the closest bigtooths thrive in the east, several hundred kilometers away.

Grossman’s work with Drs. Nick Deacon and Jeannine Cavender-Bares from the University of Minnesota on the genetics of the trees conclusively showed that they are indeed hybrids. His hypothesis is that they are relics from some 4,000 years ago when the climate supported both species. As a result, his work also explores the effects of climate change on temperate trees.

Grossman is now working with the maples at the arboretum — the most important collection of that species in the world, according to Arnold Arboretum director Ned Friedman, who briefly joined our group. Grossman aims to study how drought tolerance has developed in maples over thousands of years. The results, he said, could help evaluate their current vulnerability and create tools to make decisions about what to plant and where.

Research at “the Arb”

Friedman noted that the arboretum’s Weld Hill facility — where we met for Grossman’s talk — is home to many different research projects related to plants, from genomics to climate change. In 2017 some 90 projects were underway. He invited NESW members to subscribe to his blog, which features photos that are available for non-profit use, and to feel free to contact the Arb for any additional information.

~ Elizabeth Thomson

Image: NESW member Eric Smalley (left) with Arnold Arboretum Jake Grossman. The two sit behind a table made from a black walnut that was a specimen tree at the Arb for many years before it had to be cut down.

Join your fellow New England Science Writers on the evening of Tuesday, Jan. 15, 2019, for a small-group discussion about the potential effects of climate change on trees in the Arnold Arboretum. We’ll be meeting with Jake Grossman, a Putnam Fellow at the Arb who studies how the evolution of temperate trees, such as aspens and maples, has shaped their capacity to survive hot and dry conditions. Jake is using this information to forecast the vulnerability of these trees to ongoing climate change.

Tuesday, January 15, 2019, 6:00 PM to 8:00 PM
Arnold Arboretum
Weld Hill Research Building, Walnut Conference Room
1300 Centre St., Roslindale, MA

Space is limited and the pizza is on us; RSVP to reserve your seat!

Please contact event chair Elizabeth Thomson with any questions.

Image: Plant Image Library/Flickr