Photinia Spreading in Princeton's Woodlands

Asian Photinia (Photinia villosa) is a shrub that land managers in the Princeton area are targeting for removal from natural areas. It was sold by Princeton nurseries many decades ago, and has begun invading the local woodlands. Why are we so worried about this shrub that turns a pretty golden color in the fall, with bright red berries?

There are many reasons. For one, the shrub appears not to be edible for wildlife, and 2) the shrub has shown a capacity to out-compete the native shrubs and forbs wildlife do use for food. The spreading monoculture of Photinia in the forest understory is rendering the landscape less and less hospitable for the native diversity we seek to nurture.

An additional reason for focusing on Photinia is that it has yet to spread across New Jersey. Action now in the Princeton area could prevent Photinia from becoming a statewide pest.

This is a typical sight under berry-producing Photinias: a dense clustering of seedlings that leaves little or no room for native species to survive.

Photinia is very easy to spot this time of year. Nearly all native species have already dropped their leaves, making the woods a color coded picture of various invasive species. Honeysuckle shrub leaves are still bright green, Photinia's are golden yellow.

Here's what the woods looks like after a very dense patch of Photinia has been cut and stacked. Not as pretty, to be sure, but it's the first step in restoring a more edible native landscape for wildlife that will also be pleasing to the eye.

Homeowners are encouraged to identify and remove Photinia. Though it may be appealing from the standpoint of its deer resistance, the spread of the berries threatens the ecological balance far beyond the boundaries of one's backyard.

Nature Walk Sunday, Oct. 30, 1-3pm, Herrontown Woods

Fall colors beckon at Herrontown Woods. This Sunday, Oct. 30 at 1pm, I will lead a nature walk entitled "The Color-Coded Forest." This is the time of year when trees slip out of their green anonymity and reveal their identity through color and texture. Meet at the Herrontown Woods parking lot at 600 Snowden Lane, across Snowden from the Smoyer Park entrance. Sturdy shoes are a good idea. Maps at this link.

The Color-Coded Forest

Even this late in the fall, some shrubs and trees announce their identities by the colors of their leaves. They can appear as if a child carefully colored in a number-coded landscape-- oaks and blackhaw Viburnums bronze, the Asian photinia a golden yellow that turned to dark brown in the hard frost. Here is a photo of Pettoranello Gardens, with native oaks bronze above a shrub layer of still-green exotic honeysuckles.

The logic here is that the honeysuckles evolved in a milder climate on another continent, whereas plants native to America adapted to longer winters by dropping their leaves earlier.


Just upstream of Mountain Lakes, the extent of exotic invasive shrubs is especially revealed this time of year, as the vistas open up. The pink of winged Euonymus has just fallen, but the invasion of honeysuckle shrubs can easily be tracked by their persistent green.

Using Flowers To Read a Landscape

Flowers, like fall colors, create a color-coded landscape that can provide a snapshot of trends in plant populations. Blooms have seemed especially abundant this spring, with native dogwoods and Rhododendrons laden with flowers, and now the elderberries, Korean dogwoods and catalpas showing profusion. Catalpas have a knack for sprouting along edges, then spreading their branches of elephant ear leaves (front right in photo), tubular flowers and long seed pods up and over everything else. The branches take interesting, gnarly shapes. When catalpas are in flower, it's easy to notice how they have gained dominance in that prime front-row seating along the edge of this clearing, on waste ground near the Princeton Shopping Center. The opening itself is being taken over by Chinese bushclover, which also tends towards exclusionary dominance.

Nature Walk This Saturday, 10am-noon, Herrontown Woods

For all those who happen to be fancy free and wanting to get out tomorrow, I'll be leading a nature walk through the color-coded forest at Herrontown Woods in the morning. Meet at 10am at the preserve's parking lot, which is at the end of the deadend road opposite the Snowden Lane entrance to Smoyer Park. Included in the walk will be a visit to the grounds of the Veblen Farmstead, and a discussion of recent progress towards preserving and restoring the long-boarded up buildings there.