Invasive vs. Aggressive: They are not the same

In Florida if given a chance, Bidens alba will completely take over a disturbed area, but this doesn't mean that it's invasive. 

A polka-dotted wasp moth sipping nectar from a bidens floret.
For more information see An Exception to the Rules

Native plants are NOT invasive. 

They belong here and work well within the natural ecosystems. A pioneer plant like beggars' ticks (Bidens alba) is certainly aggressive and efficient at completely covering a disturbed site, but after a couple of years, it will give way to other plants in Mother Nature's succession parade, which  depends upon where it's found. The plants that take over could include broom sedge (Andropogon spp.), goldenrod (Solidago spp.), dog fennel (Eupatorium capillifolium), which then my be replaced by pines and oaks after a few years.

Definition:
- An invasive exotic plant is a naturalized exotic plant that is expanding its range into natural areas and disrupting naturally occurring native plant communities.     
                         via Florida Exotic Pest Plant Council  (www.fleppc.org)

Invasive plants may not be aggressive

On the other hand, as a gardener just looking at your landscape, you might not be able to determine which plants are invasive and which are not. Some relatively tame landscape plants like heavenly bamboo (Nandina domestica) and Mexican petunia (Ruellia brittoniana) are on the FLEPPC Category I list of invasives, while others like wedelia (Sphagneticola trilobata) are aggressive in the landscape, but are only on the Category II list.

This mailbox planting of mostly nandina does not appear to be overly aggressive.

But the birds eat the berries and deposit them (with a
dollop of organic fertilizer) far beyond your yard.

Nandina domestica


You can purchase this plant in any number of big box stores and at plant sales throughout Florida, but it is invasive here.  FLEPPC has placed it on the Category I list as most invasive for all of Florida.It is also been proven to be toxic to birds.

If you have it on your property, remove it ASAP. Plant beauty berry (Callicarpa americana), one of the native azaleas (Rhododendron spp.) or a shrubby holly (Ilex spp.) instead.

You can find natives grown from Florida stock at www.plantrealFlorida.org
Mexican petunia (Ruellia simplex) is highly invasive even though you might be able to control it
in your landscape.

Ruellia simplex

The Mexican petunia (Ruellia simplex) is widely sold and widely planted.  It's easy to care for and blooms throughout the season. You may be able to keep it trimmed back in your yard, but it's on the move into our natural areas. There is a variety that is sterile, but if it looks the same as the invasive type, who really knows what you're really buying?

Botanical note: R. tweediana and R. brittoniana are synonyms. See Florida's Plant Atlas

Natives to plant instead include dotted horsemint (Monarda punctata), Spanish needles (Bidens alba), and snow squarestem (Melanthera nivea).

Wedelia: the beautiful invasive

Sphagneticola trilobata

Wedelia or creeping ox-eye (Sphagneticola trilobata) can cover your whole landscape, so you might not be surprised to find that it's a Florida invasive, but it apparently has not invaded enough of our natural areas to be included in the top 76 invasives and so is classified as a Category II invasive, which is on the watch list.

Creeping natives for Florida include dune sunflower (Helianthus debilis), railroad vine (Ipomoea pes-caprae), and sunshine mimosa (Mimosa strigillosa).
Wedelia can cover your whole landscape and invade your lawn.

A long-tailed skipper (Urbanus proteus) on a Bidens alba.

What can you do about invasives?

The problem with invasives is that their infestations will continue to grow unless we all act.  Remove invasives from your yard, don’t purchase them, and complain to the store management when you see invasives for sale.  Be part of the solution.  Don't be part of the problem.  When creating the priority list of what to in your landscape, removing invasive plants needs to be at the top of the list.

Meanwhile, enjoy the parade of pollinators on your natives including the aggressive, but not invasive, Spanish needles (B. alba). 

Hold still! A gulf fritillary (Agraulis vanillae) enjoys a drink.

A honey bee (Apis spp.) stops by.

A Eastern pondhawk (Erythemis simplicicollis) hunts for prey.
For more info see, Attracting Damsels and Dragons
For more on invasives here is a group of FNPS posts by various authors, which cover a variety of topics:
Invasive vs. Aggressive... Part 1
Invasive Exotic plants
Invasive Species Week Feb 26th to March 4th
Removing Invasives in Mandarin a team effort
Mexican Petunia: a Plant Gone Rogue 
Good Plants Gone Bad
Australian Pine: One of Florida's Least Wanted

This is only about half of the posts on this topic posted on this blog since 2010. We are serious about educating you, and anyone you talk to, about how important this is. There are still people who argue, "Well it's not invasive in MY yard, so it's okay." 

Well, it's not okay and we are spending millions of dollars (both private and public) to fight this problem.  Again: DON'T BE PART OF THE PROBLEM! PLANT NATIVES!

Post and photos by Ginny Stibolt

Comments

walk2write said…
Good advice. I made the mistake of planting that Ruellia when we first moved here, and I'm still battling it. I'm thankful that I confined it to a very small area in the yard. I wish that the nurseries and big box stores would take some initiative and not sell these things to unsuspecting people.
September 21, 2013 at 10:56 PM
Ginny Stibolt said…
Yes, our invasive plant issue is not going to go away until the retailers buy into it and the only way that will happen is if we all object to those plants when we see them.
September 30, 2013 at 4:48 PM
Unknown said…
Excellent distinction. Thank you! Great article!
July 14, 2019 at 9:53 PM
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