Invasives 2

My interest in plants began about 15 years ago when two students Alison Cella-Mowatt and Caitlin Lindé decided to do a independent study project on Native American medicinal plants. We naively hoped to associate these plants with specific environments and use them as possible predictors for locating Native American campsites. We learned a lot about the plants and environmental change over the last 15,000 years, but we were all surprised to learn the number of non-native species that make up the plant life of New England today. The girls went on to bigger and better things in college while the research they began research slowly grew to become a database of over 400 plants that have been or can be found at Sheep Pasture.

The database tells us that about 140 of Sheep Pasture's  plants are non-native. Of those less than 30 are considered invasive. The simplest definition of an invasive plant species is a non-native that has the ability to displace or diminish native species or limit species diversity or alter the balance of an ecosystem. That should eliminate species that, like us, have naturalized in the environment. People sometimes confuse weeds with invasive species. A weed has been humorously defined as any plant in a place where it doesn't belong. A carnation that pops up in a field of garlic is a weed, but it is not an invasive. In the world of birds a flock of Canada geese on a golf course can be a "weed," but a family of mute swans are invasive because they are non-native and uproot and damage pond vegetation and displace native species of waterfowl with their truly nasty dispositions. Back in the world of plants, for humans, no matter where it appears, poison ivy is a weed because it makes us itch. However, it's not an invasive because it's native and "fits" into the ecosystem.

Plantain is the common name for two non-native weeds. They may hold the record for being the first plants to be placed on a "watch list" for invasiveness-the Native American name for these two are white-man's footprint because the plant quickly took root wherever Englishmen walked due to the habit of plantain seeds sticking to shoes. Whether you recognize the name or not, you are familiar with these little immigrants. Here's their mugshots:

That's common plantain.

This shows English plantain flowers. The leaves are more lance shaped then common plantain. The two plants share a common genus Plantago, but have different reproductive strategies and somewhat different environmental needs. They have been around for so long in New England that it's impossible to tell if they displaced any native plants, but they seem to fit into the ecosystem pretty well. By this I mean local bugs eat them with the same verve as they do native plants. John Eastman's indispensable book The Book of Field and Bog notes fungi that attacks the leaves and seeds, flea beetles attack common plantain while the sap beetle prefers the English plantain. Everyone recognizes the wooly bear caterpillar and plantain is a favorite food plant for them. The seedpod weevil eats the seeds as do many birds, chipmunks, and mice. Grouse, rabbits, deer and domesticated grazers all eat the leaves. In other words plantains have biological controls that keep them in check and prevent them from becoming invasive.

We'll finally look at that Globe article, and it's so-called new view of invasives in tomorrow's blog.