Sadly, part of winter work this year at the GFE includes removing our beautiful Mexican feather grass (Stipa tenuissima or Nassella tenuissima). This lovely, mobile, golden grass has been a signature plant in our border, framing our gates and stairways.
But we have learned that this grass, while well-behaved in our garden, has become weedy and invasive in neighboring wild lands. Sometimes imported plants can compete more vigorously than California natives even on their own turf, and choke out or forever alter our precious native ecosystems.
Many of the worst invasive exotic plants such as Algerian ivy, broom, pampas grass and eucalyptus, were originally planted intentionally by farmers, gardeners, and landscapers. They were not trying to do something bad, they had no idea that their introductions would wreak havoc on nearby native plant communities and wildlife. The same cannot be said of nurseries and growers who still propagate and sell invasive exotic plants today, when much more is understood about ecological impacts and interdependence. Environmentally responsible gardeners should always check with their nurseries and patronize nurseries which do not sell invasive exotics.
With our Mexican feather grass, though, we faced a moral dilemma. We love our Mexican feather grass! And this plant is not listed as an invasive exotic now. It is suspected, and reported, but its official listing is “species nominated but not reviewed” in the 2007 inventory update of the California Invasive Plant Council. It can take years for a plant to move through the complex process of being listed as invasive. Meanwhile, each plant is setting thousands of seeds each season. And the activists on the ground, the dedicated volunteers who spend their weekends weeding ice plant out of the GGNRA or broom out of Mt. Tamalpais, are observing the spread of Mexican feather grass.
In the end, gardener’s common sense resolved the dilemma for us. As anyone who has managed a farm or garden knows, it is easier to stop an invasive weed before it spreads than to control it afterwards. As the old timers say, “seed one year, weed ten years.” That’s why we decided to sacrifice our Mexican feather grass. If you’ve been following the GFE story, you know that we did the same with our licorice plant (Helichrysum petiolare) last year.
Both of these plants have wonderful qualities in the landscape, that’s why they became popular with gardeners and nursery growers in the first place. Tough, climate appropriate plants, they both offer colorful foliage and interesting textures that earn their keep in any garden design.
But it is just the most successful garden plants that sometimes hop the fence and become problems in wildlands. To learn more about invasive exotics and the efforts to protect native plant communities, look up the California Native Plant Society and the California Invasive Plant Council.