I took a quick walk at Wareham Land Trust‘s Agawam River Trail after work today, enjoying the abundant late-day sunshine. Although signs of spring were seemingly everywhere, from the red-winged blackbirds calling in the nearby wetlands to the red maple flowers bursting in vibrant color, I did notice an interesting trend. At least five different plant species were pushing out new green leaves, but none of these were native. 

1. Garlic mustard (Alliaria petiolata)

2. Multiflora Rose (Rosa multiflora)

3. Shrub Honeysuckle (Lonicera sp.)

4. Autumn Olive (Elaeagnus umbellata)

5. Japanese Barberry (Berberis thunbergii)

There’s enough of a trend here that you may have started to wonder “why?”. Well, not all non-native plants are aggressive enough or problematic enough to be considered “invasive”. However, those that are, generally become so because they are able to successfully outcompete the native flora. Although there is often a combination of reasons a particular invasive species may be able to outcompete the local species, the five plants shown above have one important quality in common: by opening their leaves first, these non-native plants gain an advantage by being able to start photosynthesizing earlier in the season than our native plants. This not only allows them to acquire more energy from sunlight, but it also results in their leaves creating shade in the early spring that may further limit the growth of native species. As a result, it is unsurprising that all five of the early-leafing plants above are found on the Massachusetts Invasive Plant List.  

On your next walk, pay close attention to which plants are already unfurling their leaves. Can you identify them? How many are non-native?