Native plants are an interesting subject matter. You regularly find people that encourage planting them, but you also come across articles that make you second guess the “facts” about native plants (like this one). The reality is that “native plants” is the new buzzword in the horticultural industry. The truth about native plants is somewhere in between what you usually read. Below we’ll discuss what is true and what is a myth. Many times statements are misrepresented in the broad blanket statements that are commonly repeated.
What Is A Native Plant?
This definition of a native plant changes depending on who you ask. Differentiation in time periods, human intervention, and places are the main factors that makes definitions different. There are several problems with the way these indicators are applied. One easy example is saying that a plant is native to a state. States are imaginary lines drawn (by Europeans might I add) and don’t identify where it is actually native to. California is an example of this being wildly confusing. A Joshua tree is native to California, but it won’t grow in a good 80%+ of the state, so saying it is native to California is barely a decent description of where it thrives.
Below are a few definitions (and my ramblings about them) for you to see the variance:
A plant occurring naturally in an area and not introduced by man; indigenousGardenWeb
A plant that lives or grows naturally in a particular region without direct or indirect human intervention.USDA and US National Arboretum
A problem with this definition is that there is no way to verify what has or hasn’t had human interaction. The only way to do that is to limit the time frame. Any attempt to verify that there was no human interaction is surely not scientific due to the nature of an inability to prove it, but we overlook that entirely in any definition with human interaction as a limit. Humans are a part of this world just as any animal is, but for some reason not stated we are disregarded in these definitions entirely.
Any plant which is a member of a species which was present at a given site prior to European contact.California Native Plant Society
This is just silly, as it discards the human intervention of all Native American Indians, but accounts for anything Europeans did (typical attitude of the US). An example of a plant being manipulated by human interaction is bitterroot. It was considered rare east of the mountains, but has an amazing ability to be uprooted, dried out for months, and replanted, making it a perfect fit for moving where it was convenient.
“Because bitterroot was relatively rare east of the mountains, the Blackfeet often traveled across the passes to gather, trade, or raid for the precious plant.”https://www.nps.gov/glac/learn/education/native-american-plant-use.htm
The emergent qualities of pre-EuroAmerican chaparral plant communities that made them so important to indigenous subsistence economies and cultures, i.e., their biodiversity, productivity, and abundance, were not merely products of natural ecological processes. Native people deliberately manipulated chaparral to enhance these qualities. They did so because chaparral contained and supported so many useful species, but the converse was in a sense true as well. Chaparral supported an abundance of many useful species because of Native management. Through creation of landscape mosaics of chaparral and herbaceous communities, this management conferred a degree of spatial, structural, successional, and biotic diversity that exceeded what would have been the case in the absence of human intervention
(Anderson and Rosenthal 2015)https://egret.org/sites/default/files/andersonkeeley2018.pdf
Now that you’ve made it through that, I’ll give the definition that I think best describes what a native plant is:
“Native plants should be defined as those that have evolved and adapted to a specific location and have remained genetically unaltered by humans.” Wasowski, Andy. “Provenance, defining our terms.(native plants).” The American Gardener 77.6 (Nov-Dec 1998): NA
Myths About The Reasons To Plant Native Plants
The main reasons to grow native plants that we commonly hear are that they’re well adapted to the surrounding area and climate, they support local wildlife, they need less chemical sprays to manage, they require less maintenance, and they don’t take over your yard. While there is some truth to some of these reasons (for some plants), there is more that goes into them.
Well Adapted To The Surrounding Area
My favorite thing I read about this subject stated “If native plants are better suited to your area, then why do we have any concern over non-native plants threatening native plants?” The reality is that they typically aren’t well adapted to your area.
“Native” plants may be adapted to the local climate in the surrounding environment, but your backyard or a shopping center is nothing like the natural environment of most native plants. Alkaline pH from lime leaching of concrete, increased heat load from reflecting surfaces, air pollution, soil compaction, and inconsistent layers of soil with poor aeration and drainage are all things that separate the urban landscape from the surrounding native landscapes. This is where exotic plants come in to play. Some are able to handle adverse conditions that are similar to our urban environments, and are therefore planted more frequently. When these local conditions are still favorable for native plants, they too can be used in these situations.
For our local Mojave Desert climate, great examples of exotic plants that are perfect for our urban environments are: olive, pomegranate, lavender, rosemary, Italian cypress, palms, and many other mediterranean species. These species can take the increased heat from urban areas, high alkalinity, pollution, poor and compacted soil, and also do well with little water.
There are, however, native plants that are adapted to these conditions as well. Most states have some type of resource to learn more about each native plant. Calscape.org is a good resource for California native plants with an example of the California juniper. It states at the bottom its natural setting and give examples of soil that suits its needs.
Supporting Local Wildlife
Non native plants can do just as good as any native plant when it comes to supporting local wildlife. Native plants can also be harmful to local wildlife and ecosystems, see Doug Fir Doug fir trees do exactly what supporters of native plants suggest exotic plants do, outcompete native species and create a monoculture that decreases biodiversity, food and resources for wildlife. Do exotic plants support wildlife in the same way as native plants, no. Can they be just as effective and sometimes better, yes. This article details how research articles will leave out information that doesn’t fit their narrative when stating that non native plants do harm to the local wildlife.
A good example is that of the western bluebird. They commonly feed on insects, but feed on berries in the winter time. The following common landscaping plants that are non-native provide food for this bird: barberry, bradford pear, chinaberry, waxleaf privet, cotoneaster, honeysuckle, olive, white mulberry, and various elaeagnus species. This is a small portion of a large list of potential food sources for the western bluebird that you can find more about here.
Needing less chemical sprays is seen as a benefit of native plants, but there is a small wrinkle in that statement. It assumes that if you have native plants, you’ll have native pests with native predators and that it’ll stay in check without pesticides. The truth is that a large majority of your neighbors don’t have any native plants (or only have native weeds), and therefore you don’t have a local abundance of natural predators. Luckily for all homeowners, predators go where the food is and adapt. You see this with gardens, as you plant a massive plot of non native food producing plants (that just happen to support the local wildlife…) you get pests with it. As the years go on you’ll see the natural predators “moving in” because you are giving a good supply of food. The main problem can be if you import exotic plants that carry additional pests that aren’t naturally occuring in your area and/or don’t have a natural predator. This is one of the reasons for strict plant importing regulations of highly agricultural states in the US.
Need Less Maintenance
Planting native plants that can’t adapt to urban conditions (such as higher pH, compacted soil, increased heat, etc.) will actually increase the amount of maintenance required. California sycamores are planted in residential areas as a drought tolerant native when they are “Almost always found in wetland-riparian settings such as streamsides, canyon bottoms with more moisture below 4,000 ft.” As California sycamores get less water they then become susceptible to diseases, pests, and water stress which adds to the maintenance needed to keep them healthy. Another example to demonstrate this idea is when azaleas (western azalea, a California native) are planted in alkaline soil. They then require multiple rounds of soil acidifier and more attention to ensure they are growing well. Are there native plants that can and will adapt to these conditions, of course, the problem is that this information isn’t always published and readily available to the average consumer. Some non-native plants adapt extremely well to these conditions and as a result are frequently planted. Ligustrum (Privet) is a great example of this, as they can handle a wide range of pH, significant amount of heat, and poor compacted soil.
They Won’t Take Over
This blanket statement is applied in a terrible way. The correct thing to say would be “Invasive plants will take over your yard,” and even then, can be false in certain scenarios. Heavenly bamboo is an invasive plant in most of the eastern United States, but in the Mojave Desert it doesn’t have favorable conditions to be invasive and functions well as a typical landscaping plant. Both native and non-native plants can take over your yard, however plants deemed “native” are classified as aggressive, rather than invasive, because they are “naturally” here. Cottonwoods and quaking aspen trees are great examples of native trees that are extremely aggressive, and are typically classified by homeowners as yep, you guessed it, invasive. Knowing a plants ability to spread by seed, stolons, roots, ground layering, or whatever other means is more important than knowing its status as a native when it comes to invasiveness or “aggressiveness”.
Everyone Has An Agenda
If all of these reasons are not always true, why do people suggest that we plant native plants so much? People that push native plants usually have an agenda related to their interests. If they don’t have an agenda, they have a solid belief that planting native plants is what’s best for the environment or it makes them feel that way. This leads to a moral agenda that is the driving force behind planting natives. Ecologists want to control the amount of native and exotic plants to not alter the environment or gene pool in which they grow, conservationists want to preserve endangered species by planting/creating more, nurserymen want to reproduce and sell the best versions of the desirable ones, and scientists and researchers have an interest in the plant staying endangered to get funding to continue researching it. There is no common goal between everyone which makes this all the more frustrating. Now, while those statements about each field were generalized blanket statements, they are true to some degree.
An excerpt from an article by Tony Avent published in March of 1995 demonstrates two perfect examples of this:
I have also read about a mutually beneficial relationships between invasive weed councils and herbicide companies. If a plant is invasive (see tamarisk) then one of the best ways to eradicate them is to poison them to keep them from resprouting or spreading. This is valuable to herbicide companies as it essentially creates a government backed supporter/purchaser. With those herbicides being banned (as in other countries) it becomes more difficult to control invasive plants. The problem is finding information on this as it seems to be well hidden. Am I a conspiracy theorist, sure if you say so, but this seems to make too much sense for a company that has more than 4 billion in sales per year to not have noticed or taken advantage of. Google “How much does the herbicide industry make per year” and you’ll only get results for the pesticide industry, with suggestions from Google to also search common phrases with pesticide instead of herbicide. Coincidence? I think not!
Anyone that pushes native plants would agree that biodiversity is vital to any ecosystem. Now if we want biodiversity, wouldn’t we want to introduce exotic species to increase that biodiversity? It seems that biodiversity is only considered important if it includes native plants. This is one of the many confusing conundrums about pushing native plants so hard with a vehement opposition to exotic plants.
Native Plant Superiority Is An Emotional, Not Scientific, Argument
Just like this blanket statement heading, the idea that native plants are always a better choice is definitely not a fact, but a mere unscientific, emotional opinion. There are times when native plants are clearly the better choice, but to try to push a native plant over an exotic plant purely because it is native is irresponsible. As a nursery we sell plenty of non native plants, but we also sell plenty of native plants. Do we have the greatest selection of native plants that we could, no, but the ones we do carry we sell tons of. Palo verdes, red yucca, desert spoon, oak varieties, mesquite varieties, desert willows, and many more native plants all tolerate our urbanized environment well and are common sellers that thrive.