Thomas Meehan, the Pink Dogwood, and crowdsourcing plant ID features

I recently visited the colonial farm and mansion called Pennypacker Mills near Schwenksville, PA. It was the family home of the Pennypackers, and the Pennsylvania Governor Samuel Pennypacker used it as a summer home in the early 20th century. During this transition, the working farm was converted into a gentleman’s country estate for the governor and the grounds were upgraded accordingly. Pennypacker by this period had both power and resources to design his estate, and hired the horticulture firm Thomas Meeehan and Sons to procure a planting plan. I was most interested in exploring this site for its connection to Thomas Meehan (1825-1901), the noted English-born, Philadelphia based botanist and nurseryman, and was curious to see how preserved the landscape was.

Besides operating nurseries in Philadelphia for many years, Thomas Meehan was a researcher, botanist and writer. He was editor of two very popular horticulture journals, being The Gardener’s Monthly (1859–1888), and then Meehans’ Monthly (1891–1902). Additionally, he was a columnist for five newspapers and wrote and illustrated books on horticulture, including  ‘The Native Flowers and Ferns of the United States”. In his early years he worked at Kew Gardens, and then went to Bartram’s Garden in 1848.

We can primarily thank Thomas Meehan for saving Bartram’s Garden in Philadelphia, which is the oldest surviving botanic garden in the United States. The property left the Bartram family in 1850 after financial hardships, and after the subsequent owner Andrew Eastwick passed away, the house again became available. The 102 acre property was at high risk for development, and Meehan started a campaign to preserve the garden, along with further help by Charles S. Sargent of the Arnold Arboretum in Boston. The efforts paid off, and in 1891 the City of Philadelphia acquired the estate and the John Bartram Association was formed in 1893.

While the Bartram estate is a must see for those appreciating colonial history, science, and architecture, the Pennypacker Mills estate is also worth the visit. It was originally built sometime around 1720 by Hans Jost Hite , who operated a grist mill on 600 acres. It then went into the Pennypacker family for eight generations when it was purchased by Peter Pennebacker in 1747. During the American Revolutionary War, George Washington used Pennypacker Mills as a headquarters prior to the Battle of Germantown, sometime around September 1777. It was also later a field hospital for injured soldiers after the battle. The mansion was redesigned and enlarged in the colonial revival style by architect Arthur Brockie in 1901 to support the country gentleman’s lifestyle.

After walking the grounds of the Pennypacker Mills estate and consulting the original Meehan planting plan, It appears as though the original framework of vegetation still maintains its original shape. Just like the 1903 plan, proposed vegetation was concentrated along the perimeter of the property at the fenceline, with small outcrops of specimen trees and shrubs dotting the long driveway. The highest attention to planting continues to be around the house, following the shape of the circular service drive that delineates a more formal space nearest to the house. The only major vegetation change is the addition of true meadows in place of grass pastures where sheep might have once grazed. I saw some nice North American native specimens including Kentucky Coffee Tree, Catalpa, Atlantic white cedar, pines, oak, spruce, hemlock and maple.


Apparently, the Meehan nursery was widely known for their ornamental trees- especially Japanese Maples. While i don’t recall seeing Japanese maple, I did notice a lot of Hedge Maple saplings [or possibly liquidambar?] seeding in everywhere, especially the meadow. Meehan is also credited with rediscovering the nearly extinct Pink Dogwood, Cornus florida var. rubra, along the banks of the Wissahickon Creek in Philadelphia. The highest rated champion tree for Pink Dogwood can currently be found in Aston, PA.


Since i’m talking about Plant ID concepts, I also want to mention a cool tool that was recently shared me called Treeversity. The project is run by the Arnold Arboretum using the Zooniverse platform, a successful citizen science web portal that hosts research activities and projects. The goal of the project is to leverage the Arnold’s existing database inventory of plant photos by asking participants to classify and identify plant parts and features for individual photo records. This process in turn adds metadata to each record, which creates endless possibilities for teaching and learning opportunities. If parts and features can be identified for all images and plants, then imagine the searching capabilities that can be had! I could run a search to see the bark of all woody deciduous shrubs in the collection, or perform a search to see the leaves of all viburnums in the collection. Most tools in botanic collections focus on the plant records themselves with regard to location and provenance, but this project is special because it focuses on the specific physical characteristics for each plant in the collection. See more on the process below:

Q: What are the steps for classifying each picture?
A: Each photo is accompanied by a list of 18 potential features to describe content included in the image. These features identify morphological or formal elements of plants (such as “Bark”, “Cone”, “Flower/Inflorescence”, “Leaf/needle”, and “Trunk”); phenological or life cycle events of plants (such as “Autumn leaf color”, and “Bud break”); condition descriptions (such as “Leafless” and “Plant health issue”); and the presence of other organisms (“Bird”, “Insect/spider/mite”, and “Lichen/moss/fungus”). Select only the appropriate features for each image; multiple features may be required to accurately describe the dominant features of each photograph. Click “Show the project tutorial” on the classify page for a detailed walk-through of classifying images.

Imagine how much easier it might have been during Meehan’s time to save species from extinction through a tool such as Treeversity. The citizen science approach is quickly becoming a very powerful resource and method for advancing research and discovery in many fields of study.


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