Every fall and spring, many people step out to see a wide range of colorful trees on CU Boulder’s Tree Walk. This fall, about 45 attendees showed up to take in the striking red, gold, and green leaves on a clear and somewhat windy October evening. Sandy Edmondson, a member of the Boulder Garden Club, showed up early.
"I’ve taken this tour before, but there is such a variety of trees, you can just learn so much from it, so, I’m here for a rerun," she said.
Vince Aquino, CU Boulder’s supervising arborist, has cared for more than 5,000 trees on the main campus for over 25 years. Equipped with a microphone and speaker, he led the group on this season’s 90-minute Tree Walk, highlighting maples, oaks, evergreens, cottonwoods, elms, ash, and more.
Directing the group toward a sugar maple, Aquino shared some details about the tree.
"It’s starting to go and this month will be really spectacular. The sugar maple often performs really well for fall color. Just about any maple sap can produce maple syrup."
A little later in the tour, Aquino points to a tree with a very different type of foliage.
"This is a honey locust with the thorns on it. And the thorns on this thing are really impressive. They can be three to five inches long and they’re everywhere, all over it," he said.
:This tree co-evolved with megafauna in North America. So, this tree was designed to defend itself from giant sloths, and mastadons and mammoths and other really unusual, by our standards, animals that would have shared its same range. Interestingly enough, these trees in those days relied on those animals to get their seeds to move around."
Klara Nitsche, a graduate student at the University, was one of the community members enjoying the tour.
"I’m new to Colorado. I came here from Georgia in August. I’ve always been fascinated by the trees walking around campus and I could tell that they were not all native so I was curious about the thought process behind it and I’m not well versed in trees or biology at all so I figured it might be nice," she said.
Arborist Vince Aquino says trees often elicit a strong reaction in people.
"It’s very personal to a lot of people. A lot of people take a very personal interest in the trees on campus and in the city and the county. A lot of things about trees are counterintuitive. People are often surprised at some things related to trees and their biology and their life cycles and different things. So, it’s kind of fun to have that exchange and I learn a lot from folks too when they have comments and questions," he said.
When CU Boulder was founded in 1876, there were very few trees. Many fast-growing shade trees like the silver maple and cottonwood were brought in and planted. Over time, the campus was transformed.
"I know a lot of the early trees on campus came in on train from back east or from the Midwest. I suspect a lot of people wanted campus to look like where they were from, because we see a lot of trees that would be native to the Midwest, to the Great Lakes, and to New England and those areas. Some of the older bigger mature trees on campus – a lot of those are non-native trees from that part of the country," he said.
One flagship cottonwood by the Old Main building lived for 140 years. It was unusually large at 110 feet tall until it was cut down in 2022. A plaque near the stump of the tree freatures several images, including the receipt for its purchase.
"It was purchased with about 30 other cottonwood trees. We believe only one remains. There’s one that we highly suspect was part of that original 30 that is still out on the quad," said Aquino.
Trees are a big part of Vince’ Aquino's lifework and he was reminded of a well-known quote: "The best time to plant a tree is 20 years ago, and the next best time is today."
"When I look around at the trees that our crew and myself have planted over the years and in 20 years what the changes that have happened with those trees and thinking about the people who planted them and what was going on and everything—I think that’s a really cool quote," he said.
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