Uncovering an Emerging Invasive Plant in Pittsburgh

In the ongoing efforts to protect and preserve Pittsburgh’s natural landscapes, our team at the Pittsburgh Parks Conservancy is always on the lookout for emerging ecological challenges. Our commitment to maintaining the health and diversity of our region’s parks often leads us into uncharted territory, where discovery and action go hand in hand. Recently, a routine day of invasive plant removal turned into a significant ecological finding, one that highlights the importance of vigilance and early intervention in environmental stewardship. Below, we share a first-hand account from one of our dedicated team members, detailing this unexpected encounter and its implications for the future of our parks.

On July 29,  my colleague Jared and I found ourselves out in Hays Woods Park, gearing up for a day of invasive plant removal with our partners at Landforce. As plant enthusiasts, we typically recognize most of the vegetation in our region, so when we stumbled upon a shrub we couldn’t identify, our curiosity was piqued. After some quick research with our iNaturalist app, we tentatively identified the plant as Christmas berry, Photinia villosa—an invasive species I’d only encountered once before in a Philadelphia park.

Discovering an unfamiliar plant is always exciting, but this find was particularly significant. In our region, Photinia villosa is still relatively unknown and hasn’t yet caused the widespread damage seen in other areas like Maryland, eastern Pennsylvania, and New Jersey. However, it has the potential to become a major ecological threat if left unchecked. In fact, this is the first recorded observation of Christmas berry in Pittsburgh, according to iNaturalist.

This shrub is a tenacious invader, capable of producing large quantities of bird-dispersed seeds each year, which allows it to spread rapidly and easily into new habitats. Once established, Photinia villosa can form dense thickets, homogenizing the shrub layer, displacing native species, and shading out germinating seedlings with its dense canopy. This characteristic makes it particularly harmful to the biodiversity and health of our local ecosystems.

Currently, Photinia villosa is not yet on any state or national invasive species lists, but it has escaped cultivation and is becoming increasingly invasive along the east coast. In these areas, it poses a significant ecological threat by creating dense shade and thickets that prevent native seeds from germinating and growing. The shrub is currently classified as an “Emerging Stage 3” invasive species in New Jersey, meaning it is common and may become regionally abundant, posing a high threat to native plant communities.

For us at the Parks Conservancy, this discovery is a rare opportunity. Most of our invasive species management involves plants that have been established in the area for decades, sometimes even over a century. This time, we’ve caught an invader early, giving us a chance to remove it before it spreads and becomes a larger problem. This approach, known as Early Detection and Rapid Response (EDRR), is crucial for managing invasive species. As the USDA notes, it’s a cost-effective and ecologically sound strategy that can save significant time and resources in the long run.

In the coming weeks, Jared and I plan to return to Hays Woods to fully remove this shrub, doing our part to protect the park and the wider Pittsburgh region from this emerging threat. 

Stay tuned for more updates as we take action to keep Pittsburgh’s parks healthy and vibrant!

-Brandon McCracken, Senior Manager of Ecological Restoration

For additional learning resources, please explore the links below. 

• https://www.lhprism.org/species/photinia-villosa
• https://landscapeplants.oregonstate.edu/plants/photinia-villosa
• https://wiki.bugwood.org/Photinia_villosa/NJ
• https://www.nps.gov/articles/000/christmas-berry-photinia-villosa.htm
• https://www.invasivespeciesinfo.gov/subject/early-detection-and-rapid-response