Good Plants Gone Bad

By Shirley Denton

We bemoan the prevalence of invasive species in our landscapes. From cogon grass to Brazilian pepper and Japanese honeysuckle, we don’t want them. I personally fight with natal grass, guinnea grass, skunk vine, and lantana, all of which insist on coming into my landscape.

But I love species such as water lily and red mangrove – and sometimes us humans have spread them beyond their native ranges. I thought it might be instructive to see how some of them have behaved in their new homes.

Global Invasive Species database

I just scanned through 3065 records in the Global Invasive Species database looking for Florida natives that can misbehave when moved into areas where they don’t grow natively. I found a dozen of them, but since I was scanning through the list, there could be more. And this is just the species that are considered to be problems in the areas where they are introduced. Some of these I knew about. Others were surprises. A couple, I didn’t even know grew in Florida!

Opuntia stricta

Opuntia stricta, erect prickly-pear cactus. This is probably the best known problem species that is native in Florida where it is not a pest. It was introduced into Australia on the first wave of western colonization where it was used as a living hedge. In Australia, it is known as the “pest pear.”

Ambrosia artemisiifolia, ragweed. Guess what, this native species of disturbed places has found its way to around the world and adds the seasonal misery of hay fever sufferers wherever it has gone.

Spartina alterniflora is the dominant species in this saltmarsh.

Spartina alterniflora, smooth cordgrass. Cordgrass is one of our important coastal marsh grasses, and on the southeastern coastline, it is important for marsh stabilization and as a nursery for estuarine fishes. It was introduced into the northwest (esp. San Francisco Bay and Pudget Sound) and New Zealand for salt marsh restoration. Unfortunately, it not only stabilizes areas that need stabilization, it takes over and eliminates habitat for wading birds and other inhabitants of mud flats.

Acacia farnesiana

Acacia farnesiana, sweet acacia. This spiny native shrub is found mostly in coastal areas and it is appreciated as a native landscape plant. It was introduced into several South Pacific areas including Fiji, Polynesia, New Caledonia, and the Solomon islands for erosion control, wood, bark, and ornamental uses. I can just imagine that thorny thickets are less than appreciated!

Andropogon virginicus, broomsedge. Broomsedge was introduced to Hawaii where it is apparently is a fire hazard encouraging fires on native landscapes that ordinarily have a much lower natural fire frequency.

Bacopa monnieri

Bacopa monnieri, herb-of-grace. This low mat forming wetland edge species has a broad natural distribution. But that does not include Grand Cayman Island where it is listed as a pest.

Ceratophyllum demersum, coontail. Coontail is a submersed aquatic, found broadly across Florida in lakes and slow-moving streams. Apparently it behaves much like hydrilla when loose in places like Europe, Asia, New Zealand, and Egypt.

Juncus tenuis, path rush, poverty rush. This small rush is found predominantly in moist places in North Florida and in much of North America. It has travelled broadly is is an agricultural weed. But what put is on the invasives list is its introduction to several islands, notable Hawaii and St. Helena where it threatens native wildlife habitats including the nesting habitat of the wirebird on St. Helena.

Paspalum vaginatum, seashore paspalum. This native has become pan-tropical and is noted for reducing biodiversitiy in areas where it forms monocultures. It is valued as a turf grass and forage grass. It is noted as problematic in New Zealand and the Galapagos Islands.

Rhizophora mangle

Rhizophora mangle, red mangrove. Very important in Florida for coastal stabilization, someone introduced it into Hawaii. Somehow, I don’t imaging mangrove thickets having much appreciation in Oahu.

Sagittaria platyphylla, delta arrowhead. This aquatic, highly similar to Sagittaria graminea, has been recorded in three Florida counties. It is uncommon enough, that the Florida Plant Atlas has no photos of it. It is listed as a problem plant for Australia and New Zealand.

Nymphaea odorata

Nymphaea odorata, white water-lily. Ouch. A wetland favorite for me that is native to much of eastern North America. It has been introduced into the northwestern North America where it grows far too well.

And so...
A dozen of over 2871 native Florida taxa as documented by the Institute for Systematic Botany. Not too bad. Would that we only had a dozen misbehaved non-natives from the rest of the world!

Acacia farnesiana, sweet acacia: its thorny thickets may be  less
than appreciated in Fiji, Polynesia, New Caledonia,
and the Solomon islands !

References:

Global Invasive Species Database. 2012.

Wunderlin, R. P., and B. F. Hansen. 2008. Atlas of Florida Vascular Plants.[S. M. Landry and K. N. Campbell (application development), Florida Center for Community Design and Research.] Institute for Systematic Botany, University of South Florida, Tampa.

Photographs: Shirley Denton, http://shirleydenton.com

  Posted by Ginny Stibolt