A weed by any other name is still a weed even if it doesn't look like one. If only everything in our gardens thrived as well as weeds. Here is Angela O'Callaghan.

When we hear that a plant’s a weed, we might have a mental image of something unpleasant to see, touch or have nearby, like a stinging nettle or a thistle.

If that were true, weed control would be so much less challenging than it is – everybody would want to remove the pests!

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The unfortunate fact is - a plant doesn’t need to be ugly to pose a big problem. Some of our most environmentally destructive weeds were actually introduced as lovely landscape plants! Onlyafter they’ve become overly successful, and begin crowding out members of the native plant community, then we see how negative certain plants can be. Loss of native plants will also affect native animals, which might not be able to use the newcomers for food, or nesting. Lots of problems can ensue from a serious invasion.   

One plant that’s almost everywhere now is green fountain grass, Pennisetum setaceum. It’s so hardy, it has thrived wherever it’s been introduced including the western United States. It’s drought tolerant, so clearly it has an advantage over many other landscape plants. The Nevada Invasive Weed List has included it for years, but it’s still spreading.

It isn’t all that troubled by fire, so on the rare occasions when we do have fires, the desert natives don’t survive nearly so well as this weed does. It also has a faster growth rate than they do. Lately, you can see it all over, anywhere it finds water – home landscapes, the shores of Lake Mead (as if the lake needed more problems); it’s even popped up in highway medians.

fountain grass Muhlenbergia emersleyi flowers

Pennisetum setaceum, green fountain grass, can invade urban and rural landscapes. Photo: A. O’Callaghan 

Muhlenbergia emersleyi flowers in late summer to fall. Photo: A. O’Callaghan

This grass forms individual clumps of two-foot long leaves, and from summer through fall, it produces flower plumes that can reach five feet tall. Most of the weedy ones tend not to get much more than about three feet. While it was being sold for landscapes, the general assumption was - it was sterile, and couldn’t produce seeds. That was incorrect. Each flower plume produces many, many seeds, which spread widely, and they can stay viable in the soil for years.

Other plants might be confused with this weed, green fountain grass, and the confusion’s with its close relations. One problem is - green fountain grass is also known as crimson fountain grass, and sometimes the flowers can look reddish. What adds to the muddle is that crimson fountain grass isn’t the same asred fountain grass. The weed is the species, but the others, like red fountain grass, are truly sterile hybrids.

If you do have a clump or two of this, especially if it just appeared uninvited, dig it up, pull it out, bag it, and throw it away. This is one plant you don’t want to put in your compost. Digging it up may sound easy, but the root system can grow a foot deep, and you want to remove as much as you possibly can.

Even if you installed green fountain grass deliberately, before we learned how invasive it really is, consider replacing it with something else. It’s not that the plant police are going to come to your garden, but who wants to contribute to environmental degradation?

Other plants have similar growth habits – low, clumping, flowing leaves and even similar flowers. For instance, Muhlenbergia species are cultivars of deer grass, and the flowers they produce are even more gorgeous. One of them is named ‘Regal Mist’ and when it blooms, it’s bathed in a crimson haze. There’re many others that’re also fabulous. Some Nolina species are called bear grass. They aren’t grasses but they look like them, and you can’t help but admire their flowers too.

I hope you’ll take a look around and ask your neighbors to do the same. This weed is bad, and we need to get it out.

For KNPR’s Desert Bloom, this is Dr. Angela O’Callaghan of the University of Nevada Cooperative Extension.

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