What are Invasive Plants
I had never thought of the magnificent Casuarinas that loom over the southern exposure of my house as invasive. Massive, yes. Incredibly hard wood, yes that’s why it’s called ironwood. And bright red roots aggressively seek moisture and nutrients. When I was first getting the hang of worm composting a few years ago, I made the mistake of placing the worm bin directly on the ground. It was summer. The bin was about 20 feet away from one of the biggest trees. It was well watered and shaded from the harsh heat, but what I found out too late is that the roots had invaded the worm bin. By the time I noticed the roots had reached throughout every part of the worm bin and most of the worms had migrated out. This surprising event made me recognize my need to be more vigilant if I wanted success with vermi-culture. The trees near my house are over 50 feet tall, having been allowed to grow tall and thick over twenty years or so, but this tree can also be managed as a low hedge through coppicing. The needle-like vegetation is nutritious to sheep and cattle. This tree’s versatility and value as a forage make it a winner, just one to watch out for.
Another introduced plant that I have been sparring with is the rootstock of a Passiflora that sends endless runners to suck moisture then launches new shoots over established plants. I take comfort in the fact that it is hard to eradicate by remembering that it produces a lot of succulent green matter for the compost. With great effort it could perhaps be trained on an attractive topiary structure, but it’s flowers are not the showiest and the fruit are not edible. Best for the compost I think.
The worst ‘weeds’ are classified by their invasiveness. They have the ability to become resistant to herbicide sprays, so farmers are advised to vary and ‘change up’ the sprays with different products to fight the development of herbicide resistant weeds. Unfortunately I cannot resist mentioning that the one thing weeds will never become resistant to is the hoe.