Baldwin Park Arboretum

In August of 2024, through the efforts of the Friends of Matthias Baldwin Park, our Park joined 872 other arboreta in the world as an arboretum certified by the Morton Arboretum in Illinois. The Park is certified as Level 1, which means it meets the following criteria:

it has an arboretum plan;
it has a governance group;
it has at least 25 taxa (species or varieties);
the trees are labeled as to at least genus and species;
the labels and information on the trees are available for public access;
there is a staff, paid or volunteer, that attends to the needs of the trees;
there is an arboretum public dimension like an educational event focused on the trees.
other desirable features include giving outreach help to other organizations, supporting the accreditation of new arboreta, school programs, and community greening efforts.

For comparison, the 4,000 trees in the combined East Laurel Hill and West Laurel Hill Arboretum constitute only a Level 2 arboretum. The Morris Arboretum in Chestnut Hill is the nearest Level 4 arboretum, a level which requires a paid staff and a research arm. Level 4 is the highest level.

How does our Park meet the above Level 1 criteria:

a plan for the Park layout was originally made by Athena Tacha, the landscape artist who designed the Park as a Percent for Art project in the 1980s. The City and the Friends group has worked to maintain the basic outline of the original plan with additions to replace dying trees;
a group within the Friends works with the Board of the Friends and the City to preserve and enhance the arboretum;
as this updated spreadsheet shows, our 67 trees represent well more than 25 species or varieties;
in 2020 the trees were labeled, each with a common name, genus, and species. The tags have a QR code linking to a web page with an article about that particular tree within the context of the Park. Each article includes a brief high school-level botany lesson;
our "staff" for the arboretum is a group of volunteers, basically your neighbors, none of whom are paid. Planting, watering, trimming, attending to the health of the trees, and weeding consume hundreds of hours each year;
self-guided tours are easy to achieve in the Park by using the tree tags. Neighbors are encouraged to get familiar with the trees by looking at one tree and its QR code per day. The Friends also offer at least two free guided walking tours of the trees per year;
the Friends have also offered free tours of the Park to local high school groups and have worked to get the empty tree pits filled in the neighborhood. The gingko and American elm on the northeast corner of 20th and Hamilton Streets were planted by members of the Friends. We have consulted with nearby folks at the Friends of Bulldog Park, the new Triangle Square Park Committee, and the embryonic Arboretum at the Philadelphian.

The north side of the Park on November 22, 2025, looking east.
The orange leaves of a post-peak red maple, planted in 1991, are seen on the left in foreground. The beautifully-shaped bald cypress planted in 2022 is turning golden before the needles fall off.
The landscaping on the north side of the fence is part of the North x Northwest townhomes.

An arboretum is ideally more than just a bunch of trees. To some folks, a tree is a tree no matter the species (or genus, or family, or order, or class, or any other higher taxonomic level). The Franklinia tree in the Park, however, is as distantly related to the sugar maple as a human is to a manatee. Same class but a different order.

Diversity of trees is important: for human interest, for animal habitat, and for disease resistance. A rule of thumb for urban tree placement is the 10-20-30 rule: in a given area, no more than 10% of the trees should be of the same species, no more than 20% of the same genus, and no more than 30% of the same family. As you can see on our spreadsheet of our tree inventory, we are doing pretty well. There are 67 trees in the Park, which includes the street trees lining 18th and 19th Streets along the Park. We somewhat arbitrarily excluded the five species growing in the area beyond the fence in the south side of the Park. The largest single number of one species is accounted for by six red maples, four of which are on 18th Street. There are also six hawthorns encompassing two different varieties (four with thorns on 19th Street and two without thorns in the southwest corner of the Park). The largest genus category is the Pinus genus, which numbers seven and includes three black pine, two pitch pine, one white pine, and one forlorn-looking red pine. At the family taxon level there are fourteen members of the Rosaceae family, which includes the six hawthorns, four crabapples, three cherry, and the single purple-leaf plum.

A Neighborhood of Trees

When William Penn came to Philadelphia in 1682, there were already inhabitants: the Lenni-Lenape, Swedes, Dutch and English. Much of the land had been cleared for farming, and that clearance process would continue for the next two hundred years.

Ours is a Lenni-Lenape neighborhood originally named for its trees.
Detail from a 1934 map made by the Philadelphia Planning Commission and now at the Historical Society of Pennsylvania. Coaquannock means "Place of Tall Pines," and the current Matthias Baldwin Park would be located near the letter "u" in the word Coaquannock. Cohoquenock, the stream flowing into the Delaware River at right, would be renamed Pegg's Run by the British colonizers and would play a role in the Callowhill Cut, as discussed here. The same physical characteristics that made the area favorable to the Lenape, including many streams between two broad rivers as discussed here, made the area appealing to Penn. For more on the cosmology of the Lenape, see the article on our newest neighborhood mural unveiled in 2019 here.
With reference to "place of tall pines," as of November 2025 there are seven pines in our arboretum, the tallest, a white pine, leaning at a 45-degree angle. The other pines are shorter: three black pines, two pitch pines and a single red pine.

In 1681 William Penn received the land grant of Pennsylvania as payment of a debt owed by the king of England to Penn's father. Penn, modest Quaker that he was, wanted to name the land Sylvania, Latin for land of woods. The king insisted that the father's name be included, thus Pennsylvania, Penn's Woods. Penn Junior named all the east-west streets after trees and preserved five squares as parks with trees. He signed his famous treaty with the Lenape under the "Treaty Elm" on the banks of the Delaware River in 1683. When Europeans first arrived to what would become Pennsylvania, forest covered 90% of the land. By the time of the American Revolution that percentage had fallen to 30%. Efforts were then made to preserve what was left. These measures included keeping the sheep and public hangings out of the city squares and purchasing land along the Schuylkill River to protect the water as well as the trees.

Map of the arboretum at Washington Square in 1842. Educating the public about trees was thought to be just as important as providing shade and fresh air within the City.
Photo credit here.

According to 2018 City data here, Philadelphia overall has a 20% canopy, meaning 20% of the total area has tree canopy coverage. In Philadelphia's parks, the canopy averages about 60% coverage. In 2019 the City drew up a 128-page plan for improving the tree coverage in the City. The goal is to have 30% of the City covered by trees. One might think the Baldwin Park neighborhood (16th to 21st Street, Brandywine to Vine Streets) is doing well, but we have only at about 15% coverage.

Where did the goal of 30% coverage come from? Those with green thumbs love rules of thumb. A 3-30-300 rule of thumb for urban forestry requires that every citizen should be able to see at least 3 trees from their home, have 30 percent tree canopy cover in their neighborhood and not live more than 300 meters away from the nearest park or green space. Thanks to the views from residential high-rise towers, most of us can see three trees from our residences. We need to double our neighborhood canopy coverage to reach 30% coverage. One way would be for the City to force builders to plant the street trees promised in the proposals for their buildings (looking at you, Dalian and Baldwin Apartments). By the definition of our neighborhood borders for these articles, everyone lives within 300 meters of Baldwin Park.

Portion of City canopy map from here. The map in the link also shows the average height of trees in a clump. Bigger trees are better.

Matthias Baldwin Park has the only certified arboretum in the neighborhood, but some developers have provided thoughtful plantings in public spaces. I will show these in the next set of photos, taken in the early winter so the structures of the trees can be more clearly seen without the foliage.

arboretum london plane at barnes 2026.jpg

Double rows (an allée) of London plane trees along the Parkway in front of the Barnes. These trees do great in urban environments and you see them all over Philadelphia. They are a cross between oriental plane (Platinus orientalis) and the American sycamore (Platinus occidentalis).
The Rodin Museum just west on the Parkway has similar plantings and lush grounds with benches.

arboretum cedrus deodora at barnes 2026.jpg

Gorgeous Himalayan cedars (Cedrus deodora) at the south entrance to the Barnes.

Buckeyes (Aesculus spp.) at the water feature at the Barnes off 20th Street.
The landscape designers at the Barnes are fond of linear monocultures. Along 20th Street there are Lindens (Tilia spp.) as street trees and along Pennsylvania Avenue there is a row of willow oaks (Quercos phellos) as street trees. The leaves of the latter are long and thin like willow trees.

The courtyard with picnic tables at the Community College of Philadelphia (CCP).
The multitrunked trees in the raised beds on the left are red maples (Acer rubrum) and the taller ones on the right are Zelkova serrata. Even when classes are in session this courtyard is usually fairly quiet and a good spot for a lunch meeting.

The entrance to CCP off 18th Street has a row of hollies (Ilex opaca) with red berries on the right and pin oaks (Quercus palestris) on the left. As noted in our article about the red oak in the Park here, oaks retain dead foliage through the winter. This retention trait is called marcescence, which is also well seen on the oak trees along Vine Street at the LDS meeting house site.

One of two rows of trees at the Latter-Day Saints Temple. There is a parking garage underneath these trees so they can't be too large. Our LDS neighbors have even provided benches and open daytime access to this area along Franklin Town Boulevard.

The courtyard at the North x Northwest Apartments adjacent to the Park. Studio Bryan Hanes did a great job with the plantings when the new tower was built in 2016. There are stellate magnolias (Magnolia stellata) and Juneberries (Amelanchier spp.) along the south side of the townhomes facing the Park; elms (Ulmas spp.) and tulip poplars (Liriodendron tulipefera) along 19th Street; hollies (Ilex opaca) and black birches (Betula nigra) and fastigiate sweetgums (Liquidambar styraciflua) along the entrance driveway; and bald cypresses (Taxodium distichum) and honey locusts (Gleditsia triacanthos) in the courtyard. The tulip poplars may eventually grow to be the tallest trees in the neighborhood. Right now, the tallest tree is probably the 100-foot-tall dawn redwood on the grounds of the City View Condominiums at 21st and Hamilton Streets.

The median strip on the 1900 block of Spring Garden Street, planted and maintained by two of the Friends of Matthias Baldwin Park. Heroic work!

More trees please!

If you see an empty tree pit within the neighborhood, ask the owner if they would like a tree planted in it FOR FREE. The City will plant a street tree after filling out the simple form here. The Pennsylvania Horticultural Society's Tree Tenders can also be contacted here to get a free street tree.