Where Did These Plants Come From?

I recently visited a relatively urban site that used to be near an old mill.  The site has received a grant to restore 1.5 acres of riparian corridor and 500 feet of creek in north Atlanta. I was there to help identify what plants were on the site. This inventory will be used to document the change as well as understand what native plants are there to be preserved.

No one lives on the site now but it is surrounded by buildings, both residential and commercial. As you might expect, if it needs to be restored then it has some invasive plants. English ivy (Hedera helix) and silverthorn (Elaeagnus spp., two species on site) were the two most prevalent plants. Mahonia bealei and privet (Ligustrum spp, two species on site) were there as well. Just getting started was bush honeysuckle (Lonicera maackii), but the vining Japanese honeysuckle (Lonicera japonica) was well established. Two non-native ferns were there – Japanese holly fern (Cyrtomium falcatum) and Autumn fern (Dryopteris erythrosora).

Autumn fern (with native Christmas fern below)

None of these plants were planted by people here. Where did these plants come from? They came via birds. They came via travelling mammals. They came via any critter with the capability of consuming a berry or seed and then depositing (largely by defecating) it further away.

They came as one: a seed slipping through the leaf litter until it reached fertile soil. Another one arrived and made its journey to the soil. They flowered and insects pollinated them, allowing them to multiply again and again. Some crept quietly and steadily, year after year, increasing their mass and their reach.

They were ignored by man, overlooked and unidentified. The fruit of each was carried further into the property, creating even more, choking out the light in some cases and hogging the water and nutrients as well. Native plants, some small and ephemeral, shrank back. The biodiversity of the environment decreased until the newer plants dominated the space. English ivy covered the ground and thick stands of evergreen shrubs overtook trilliums, bloodroot, and Solomon’s seal, perhaps. Will we ever know what was lost?

English ivy-dominated slopes; Japanese holly fern in cracks of the mill wall

Restoration projects sometimes report of returning native plants once the invaders are removed. Nature can be resilient if we help it in time. Free of the stifling vegetation, these special native perennials may have enough energy to come back.

I hope to write about the success of this project in the future. There were some very good native plants there, pushed back but still there. Once the sunlight hits the ground, native plants may re-emerge (some non-natives too but they won’t last!). Local restoration projects are a great way for people to get involved in the health of their community. Even people without their own garden can make a difference this way. If you have a park near you, offer to identify and remove non-native plants and see what grows thanks to your efforts.

The slope above the creek with ivy, mahonia, privet, and more