“But make no mistake: the weeds will win; nature bats last.” Robert Michael Pyle
My last post celebrated having reached over 400 identified species at Jemicy. Why, then, would these kids be cheering an effort to reduce that number?
A few weeks ago, this group went for a hike into the far Jemicy woods. I told them only that we were on a mission and brought along a bag, so they assumed that we were picking up trash. “Not exactly,” I replied, “although what we are looking for doesn’t belong here, and we’re going to try to get rid of it. It’s right under a red flag.” We found the flag, but the kids looked around, puzzled. “There’s nothing wrong here – just some grass.” I bent down and pulled up one of the low plants at our feet. It had wide, wavy leaves. “See this? It’s called wavy-leaf basketgrass. We’re not sure how it got here – probably by a seed stuck to someone’s shoe, or in mulch – but it can spread very quickly and keep other plants from growing here. So, do you think we can get every one of these little plants out of the ground and into this bag?” “Yes!”
We hunted and bagged plants until the area was clear, declared our mission a success for that day, and made plans to come back in the spring to check for those that might have evaded us.
Jemicy’s woods, like much of our region, is full of plants that are considered invasive, as defined by the US Department of Agriculture: “non-native (or alien) to the ecosystem under consideration, and… likely to cause economic or environmental harm or harm to human health.” The Maryland list contains many species that were intentionally introduced for ornamental or practical purposes – as a food crop, perhaps, or to stabilize eroded slopes. Jemicy’s Lower and Middle School campus has 20 of these, most so firmly established that there is little hope of eradicating them. While many introduced species remain contained and manageable, others “escape,” their seeds carried by birds, the wind, or inadvertent human transport. The effects of these aggressive colonizers can range from shading out native species to trapping them in a permanent stranglehold. While we do have some native wild grapes, most of the “Tarzan vines” that snake up our trees and drape the canopy of our woods are introduced and now invasive species of bittersweet (Celastrus orbiculatus) and honeysuckle (Lonicera japonica).
Porcelain berry (Ampelopsis brevipedunculata) is a more recent invader whose broad leaves and tenacious tendrils create a thick blanket along the edges of the woods – and whose bright blue berries are eagerly eaten and transported by hungry birds.
Some of these introduced plants bear a strong resemblance to native species. For years I had assumed that the spiky-stemmed, purple-fruited trees growing at Jemicy were the Maryland native, devils’ walking stick (Aralia spinosa). When I went to photograph them for inclusion on our biodiversity checklist, however, a closer look at their leaf veins revealed that they were instead Aralia elata, an introduced species now regarded as invasive.
I often cite George Washington Carver’s words to my students when we are discussing the value of plants such as dandelions or other introduced agricultural species: “A weed is a flower in the wrong place.” One of the stories that I remember my mother telling about my grandfather was that he inspected for “noxious weeds” growing along the roadsides of farms in Ontario. That term left me with the vivid impression that some weeds were worse than others, defined by our need to manage them. That “wrong place” is one that allows the plant in question to grow and spread without constraint, where it lacks its native consumers, pests, and environmental controls, and where it impinges on human interests, which increasingly include the value of ecological integrity. Garlic mustard (Alliaria petiolata) is an example of an introduced food plant that can rapidly inundate and obliterate the smaller plants in a forest understory, to the detriment of other species that depend on them.
During aftercare this week, a student brought something to show me. “What’s this?” she asked. I hesitated, envisioning the chain of events that could follow my response. Paulownia tomentosa, or princess tree, is one of those plants that was introduced here intentionally from eastern Asia, as an ornamental. In the spring, it puts out large, lovely, purple blossoms that sometimes still contain a taste of delectable nectar after they fall. They have large, heart-shaped, fuzzy leaves and interesting boat-shaped seed pods that open to release hundreds of tiny seeds. Once the wind gets hold of them, they can sail for miles.
In the end, after explaining my concern, I let the pod-finder open it and explore the seeds in a place where I thought they would not be spread. A few days later, I saw the same student pointing out more pods to another child, and explaining what they were. Nature may bat last, but educators hope we have a few innings left to help make up for a few errors.