Pull this. Plant that: fountain grass vs. desert broom
Some of the most destructive species that have been introduced to the wild started off as a pretty ornamental plant. It can seem harmless. It can even seem appropriate. In the past we were not so knowledgeable about the impact exotic species could have on a landscape. Even now that many of us are aware of the potential issues, we don’t all know what is native and what is not.
A prime example of this found all over our region, particularly in the foothills of our surrounding mountain ranges: fountain grass (Pennisetum setaceum).
We see pictures on Instagram all the time of people posing next to this plant, or capturing it at sunset. And if you didn’t know about the harm it causes local landscapes, you would think that this is a beautiful plant. And it is. But it is destructive to our native ecology.
The plant didn’t do anything wrong. People did. For a number of decades this exotic species was sold as an ornamental by the nursery trade. Also, before we knew the sort of harm introducing these nonnative species could do, government organizations would plant this for erosion control. We planted all sorts of plants we probably shouldn’t have, and these days we are paying the price for overlooking our regional ecology.
Fountain grass is problematic. First of all, it aggressively reseeds itself and displaces native species. Because it did not evolve in our landscape, it doesn’t neatly fit the niches that our native grass species fit into. Instead, it bullies its way into the flora taking up space, and sometimes forming into dense, monotypic expanses where little else can squeak in.
The other problem is that fountain grass comes from a fire-climax plant community in Africa. It can carry fire, and still come back after a burn. In the low desert, there isn’t normally sufficient fuel to carry fire in the same way. Our native grasses are sparser, and don’t tend to burn hot like fountain grass. The consequence the fountain grass will burn and all the other native species succumb to an element they haven’t evolved with: fire. Cacti like barrel cactus, chollas, and saguaros don’t come back after a fire. Nor do most of our low desert species.
Also, because the insect and animal species that live in our native landscape didn’t evolve with fountain grass, they don’t have a history of using it. Native, solitary bees much prefer native grass species for building their underground nests. Birds don’t consume the seeds of fountain grass like they do the native panic grasses (for example). Fountain grass isn’t used as a larval food plant by any moths or butterflies. It’s just taking up space and giving back little. This isn’t to say that it is completely useless to the native ecology. It just doesn’t play nice with our native ecology like the native species do.
Often this grass will volunteer in a landscape, or even be planted by those who don’t know better. People see it, think it’s a rather attractive grass, and encourage it to grow. We encourage you to remove this grass from your landscape and if you like the look of this species, consider planting one of the many, gorgeous native species available in the trade.
Ironically, some plants have been maligned that don’t deserve to be. Desert broom (Baccharis sarothroides) is one of these species.
People LOVE to hate desert broom. And we kinda get it. In disturbed soil, much like what is found in our home landscapes, desert broom can proliferate. And if you take too long to yank the plant out, it can become difficult to get rid of.
It can pop up in a hedgerow and insist on its right to exist. You can snip it to the ground and it will continue to grow back, again and again.
Also, many people find the female plants obnoxious. Desert broom is dioecious (there are separate male and female plants). The female plants produce seed that is dispersed by wind: attached to the seed is a pappus of fuzzy bristles—basically a lot of cottony fluff that gets everywhere, annoying anyone with a cleaner-looing landscape aesthetic.
Many people assume that desert broom is a noxious, exotic weed. But it is not. It is native. Also people assume they are allergic to desert broom because they see fluff, see white fuzzy flowers, and assume that what is causing their allergenic misery is this plant. Funny enough, grasses, particularly nonnative grasses (like fountain grass) are terrible allergens. While the desert broom has sticky pollen (it is insect pollinated and has evolved to cause its pollen to stick to the various insects that visit its flowers), and does not become airborne.
Desert broom has a role in the ecology of our region. It occupies disturbed soils and washes, deeply rooting into the ground and preserving our soils from erosion. The plants themselves are what we refer to as a keystone species. It anchors into disturbed soils, stabilizes them, and invites a massive amount of insect, bird, and mammal species into the site. Desert broom has nectar-rich flowers that attract such a vast array of insect species that entomologists who study the region often look for desert broom to catch what is in the area. It isn’t just the nectar-loving insects that are attracted to the plant, but also all the insects and birds that prey upon those nectar feeders. During the blooming cycle, these plants are visibly populated with activity. Even from the distance you can find these plants—just look for the mass fluttering of butterflies in the distance. This plant is also a host for many butterfly and other insect larvae.
A keystone species is one that plays a unique and crucial role in the way an ecosystem functions. The presence of desert broom determines the presence of so many other species, it pioneers disturbed soils and stabilizes them, making room for the more permanent plant species that will eventually succeed it. And it provides a wealth of food, nesting material, habitat for a wide host of other species.
If you want to avoid the fluff of the female plants, you can always plant the Thompson selection called “Starn”. This is a male that will not produce the fluff that bothers some people, and also not produce seed. So you won’t have to worry about young plants coming up all over the landscape. It also grows a bit lower than the native species that can tower over 6-10’ tall. But “starn” will top out at 3 feet tall and spread 4-5 feet wide.