Tag: natives

From Beloved to Invasive: How does it happen?

On By durhammastergardenersIn benign non-native plant, bird friendly habitat, bugleweed, conservation, crape myrtle, Durham NC, ecological sustanability, ecology, gardening, Gardening information, gardening NC, heavenly bamboo, hellebore, how plants become invasive, Invasive Atlas of the United States, invasive plants, Japanese stiltgrass, lenten rose, lesser threat invasive plant list, liriope, monkey grass, nandina, native ecology, native ecologynative plant ecology, native plants, Natives, NC biodiversity, NC conservation, NC Native Plants, New Hope Bird Alliance, non-native plants, ox-eye daisy, perennials, polyculture, privet, protecting native plants, Rose of Sharon, Russian olive shrub, sustainable garden design, sustainable gardening, sustanability, Uncategorized, urban garden, urban gardening, watch list for invasive plants

By Jeannie Arnts , North Carolina Extension Master GardenerSM volunteer of Durham County

I have volunteered as a recorder for the New Hope Bird Alliance (formerly Audubon) Bird Friendly Habitat (BFH) team since 2018. The BFH team, consisting of a plant expert and a recorder, visits homeowners’ yards to identify native and invasive plants and make recommendations for improvements to achieve an ecologically beneficial habitat for birds, insects, and other wildlife. Since I have joined the group, plants previously recognized as non-native, non-invasive plants have been moved onto the “Watch List” or “Lesser Threat Invasive” list. Other plants previously considered lower threat have been moved to a higher threat category. The question arises, “What is it that changes a benign non-native into an invasive?

When is a Plant Determined to be Invasive?

Plants are categorized as invasive once they disrupt the ecology of intact, functioning eco-systems, leading to loss of biodiversity and habitat degradation. This results in huge economic damage valued in the billions of dollars to agriculture, forestry, and personal property. Invasive plants compete with our natives for critical and often limited resources like sunlight, water, nutrients, soil, and space. Anyone who has ridden the train at the Museum of Life and Science in Durham and seen the Russian olive shrubs (Elaeagnus sp) overtaking the landscape along the tracks or been on a hiking trail in many Triangle forests and seen the stiltgrass (Microstegium vimineum) engulfing the entire ground cover of the forest floor can easily see the impact of invasive species.

Russian olive shrubs (left) out-compete native plants and dominate riparian areas primarily in central and western USA. Japanese stiltgrass (right) was accidentally introduced into Tennessee around 1919 as a result of being used as packing material for porcelain from China.  it has invaded many woodlands in North Carolina. (Image credit: NC State Cooperative Extension)

What Factors Influence a Plant to Become Invasive?

Biologists have been “vexed for decades” by the question of what causes some plants, once thought to be benign, non-invasive exotics, to become a risk to our eco-systems due to their invasive characteristics. The ecologist, Charles Elton, wrote the book, The Ecology of Invasions by Plants and Animals, in 1958 and, more than 100 years earlier, Charles Darwin pondered this question during his voyage on the Beagle (1831-1836). Johnny Randall, former Director of Conservation Programs at the NC Botanical Garden, noted that one reason plants become invasive is that in their new environment, they no longer have natural controls, such as pests, pathogens, and herbivores. This gives them an advantage over native plants that have been part of a region’s ecology for millennia; consequently, the invasives often out compete the natives.1

In addition, a plant’s propensity to become invasive is a function of the plant’s own biology, including a relatively short generational period, large seed production, its ability to reproduce asexually (without the need for fertilization), and having large fleshy fruits, such as those produced by Autumn or Russian olive trees (Elaeagnus sp), privet (Ligustrum sp.) and heavenly bamboo (Nandina sp.) With this latter trait, birds will eat the berries and deposit the seeds far from the original location of the plant.

A non-native, is especially prone to invasion when it sets its roots in a “matched habitat” similar from which it came, i.e., their native ranges tend to have similar temperature extremes, precipitation levels, and seasonal cycles. Stiltgrass (Microstegium vimineum) is an example of a plant that meets most of the criteria for becoming invasive. It is an annual that produces up to 1000 seeds per year, has no natural controls, reproduces asexually, and its seeds are distributed by the wind. In addition, the seed bank may take up to five years to germinate. Many gardeners who think they have eliminated stiltgrass on their property one year are befuddled to find a number of plants from the seed bank sprouting the next summer. The good news is that if you continue to manage the stiltgrass, you will have fewer plants each year.

Beloved Plants that Become Invasive

I think we can all agree that we want stiltgrass eliminated from our property, but there are non-native plants that have been beloved by gardeners for generations that are being added to the invasive lists, much to the consternation of gardeners. One example is the lenten rose (Helleborus orientalis).

Some hellebores  have started to escape into woodland areas and are able to stifle our favorite native understory flowers. They prevent seedlings of other plants from getting established as dense mats of their offspring grow. (Image credit: NC Extension Toolbox, Bob Gutowski CC-BY-NC-SA-2.0; Jim Robbins CC-BY-NC-4.0).

There are many good reasons that hellebores are such a beloved plant: they bloom over the winter months when very few other plants are blooming; they require little care; they are deer and rabbit resistant; they tolerate a wide range of light conditions; including light shade; and they survive even deep frosts. Unfortunately, they meet many of the conditions that place them at risk to become invasive in our region: they have no natural pests or pathogens; they can successfully fertilize themselves (although bees will seek nectar and pollen from the plants); and they produce a multitude of fertile seeds. While there is not a perfect native substitute for hellebores, the gardener may consider planting a matrix of sedges (Carex species), coral bells (Heuchera americana), and ferns, many of which are host plants, to provide winter interest .

While not yet on the invasive lists in N.C, another beloved plant that is of concern is the crape myrtle (Lagerstroemai indica). Its spread is being tracked in Southern states by the Invasive Atlas of the United States and the plant’s spread is being watched with caution by conservationists in N.C. Each flower of the crape myrtle produces a prodigious number of seeds that are carried or blown far from the mother plant. I have had a crape myrtle in my yard for probably the past 40 years and it has only been recently that I have seen it sprouting up elsewhere in my yard and ¼ acre woods.


Crape myrtles are seen along roadways and in gardens in North Carolina but conservationists have raised concerns because it outcompetes many native plants (Image credit: NC Plant Toolbox, skdavidson)

Liriope (Liriope muscari and L. spicata), bugleweed (Ajuga reptens), Rose of Sharon (Hibiscus syriacus), and ox-eye daisy (Leucanthemum vulgare) are all common ornamental plants that have been added to the NC Invasive Plant list as “Low Threat” species. While they have the potential to harm our local ecology, they are not yet doing so.

Liriope (Liriope muscari), bugleweed (Ajuga reptens), Rose of Sharon (Hibiscus syriacus), and ox-eye daisy (Leucanthemum vulgare) are plants that many of us have in our garden. They are considered to be “Low Threat” to native plants of North Carolina. (Image credit: North Carolina Toobox, Manuel-CC-BY-2.0; Jim Robbins-CC-BY-NC-ND; Frank Mayfield, CC-BY-SA-2.0)

As gardeners, we can control the spread of potentially invasive plants in our own yards or we can choose to remove them and plant a native that supports our native ecology. A follow-up blog will suggest options to consider for replacing invasive plants with natives that power our ecosystems.

Notes

  1. Personal communications Peter Schubert, NC Invasive Plant Council, October, 2024 and Johnny Randall, former Director of Conservation Programs, NC Botanical Garden, October 2024.

Resources and Additional Information

NC Invasive Plants List adopted by NC-IPC, November 16, 2023NC Invasive Plant Council
https://nc-ipc.weebly.com/uploads/6/8/4/6/6846349/invasive_plant_list_-_ranked_-_2023-11-16.pdf

Grzędzicka, E., Assessment of Habitat Selection by Invasive Plants and Conditions with the Best Performance of Invasiveness Traits, February, 2023. https://www.mdpi.com/1424-2818/15/3/333

Invasive plant Atlas of the United States University of Georgia-Center for Invasive Species and Ecological Health, October 2018 https://www.invasiveplantatlas.org/index.cfm

Jones, M., Gaster, R. Invasive Species, NC Cooperative Extension, Lee County, July 30, 2019 https://lee.ces.ncsu.edu/2019/07/invasive-species/

Moony, H.A., Cleland, E.E., The Evolutionary Impact of Invasive Species, Proceedings of the National Academy of Sciences. May 2001, 98(10) 5446-5451 https://www.pnas.org/doi/full/10.1073/pnas.091093398

Moorman, C, Megalos, M, Douglas, K. Invasive Plants and Your Forests, NCSU Extension Publication. Revised September 11, 2024. https://content.ces.ncsu.edu/invasive-plants-and-your-forests

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Plant Goldenrod for Outstanding Fall Color

On By durhammastergardenersIn bees, beneficial insects, birds, drought tolerant plants, Gardening information, gardening NC, goldenrod, landscaping for wildlife, native plants, Natives, NC Native Plants, Perennial, pollinators, Uncategorized, urban prairie garden, wildflowers, wildlife

By Melinda Heigel, NC State Extension Master GardenerSM volunteer of Durham County

Goldenrod lights up the fall garden as summer blooms fade. This plant offers a lot more than just its pretty flowers; goldenrod also supports beneficial insects and birds late in the season. (Image credit: Melinda Heigel)

Want outstanding fall color? Plant goldenrod. Nothing says fall is coming quite like the vibrant yellow hues of the this plant (Solidago spp.). In central North Carolina this perennial wildflower typically begins to appear in late summer and is a harbinger of brilliant trees ablaze, mums, and, of course, pumpkin-spice everything. You can often spot this North American native growing high and unruly by roadsides and in all sorts of wild areas. But there are ways to incorporate this beneficial plant into your home landscape.

Biology

Goldenrod is the common name for the biologically diverse Solidago genus. Currently, there are over 120 documented species, both natives and cultivars, of this stunning bloomer. According to Clemson University, botanists still have a lot to discover about this plant because some of the species exhibit polyploidy (or having more than two copies of each chromosome). This feature makes for incredibly diverse traits in species: taller, shorter, some that prefer moisture, some that like drier soils, sun, part sun, and even flower characteristics and bloom time.1

Benefits of Goldenrod

Hardy

Aside from its beauty, goldenrod has a lot of great characteristics. Overall, this plant is easy to grow and tough. Most species do well in a wide range of soil types, are heat-tolerant, water-wise, and even tolerate drought once established. Goldenrod offers a long and prolific bloom time and can benefit from regular deadheading during the growing season.

Its resilience is famous, and gardeners know that this plant can thrive and naturalize easily in the landscape (read as some healthy “management” may be necessary to divide the plant every few years to control its spread) if you plant a weedy type. Goldenrod spreads by rhizomes and wind-blown seeds. Below, we’ll address some less assertive types that can offer great alternatives in a smaller home garden. And, finally, goldenrod is deer resistant and has no serious disease or insect problems.

Wild-life Friendly

Goldenrod draws pollinators into the garden. (Left to right) Two spider wasps on goldenrod and an unknown bee species feasting on Solidago juncea’s nectar. (Image credits: Eric Benson, Clemson University Extension, 2020; Fritz Flohr Reynolds CC BY-SA 3.0)

With the growing awareness of the role pollinators play in our ecosystem and the immense survival pressure they face, more gardeners are planting pollinator-friendly plants.  Goldenrod certainly falls into this category. Many of the species produce enticing and beneficial nectar for a host of bees, wasps, flies, moths, and beetles. It is also a host plant for the wavy-lined emerald moth (Synchlora aerata). Given the bloom time, ranging from June through October, these plants provide needed late-season sustenance. They also support more butterflies and moths than any other plant in its category.  Over 115 species of Lepidoptera (the order of insects that includes butterflies and moths) larvae rely on the plants’ leaves and shoots for food. After the blooms fade at the end of the season, birds eat goldenrod’s dried seeds while native bees nest in their hollow stems for the winter. Hands down, this plant has a positive impact on wildlife in your landscape.

Characteristics of Goldenrod

As highlighted above, there are a lot of variables within the Solidago species. It’s best to do a little research on the type of plant you are buying based on the specific characteristics you seek for your garden. However, all goldenrods are herbaceous perennial plants that generally bloom between June and October. While they range in height, habit, and environmental preferences, most prefer sunny conditions.  They have a clumping, tall, or climbing habit and produce showy blooms of tiny golden flower heads in tight, dense clusters on a long stem.2 Not generally picky about soil make up, most goldenrods do prefer well-drained environments. And these plants have a wide range of growth, spanning USDA Plant Hardiness Zones 2a-8b.

From a design perspective, they provide great color and texture in the landscape late into autumn after many summer flowers are spent. Depending on the species or cultivar you choose, they work well either as a back-of-the-border or front-of-the-border plant. Their free-flowing form looks great in a meadow, natural area, or cottage garden. And of course, they are right at home in pollinator and butterfly gardens.

Recommended Types of Goldenrod

As the term wildflower might suggest, some goldenrods can get weedy and a bit unruly in the home landscape.  This plant can naturalize (spread with abandon) as it propagates by wind-strewn seeds or by underground rhizomes, so some are best left in a meadow, prairie, or woodland setting. But with so many to choose from, including ornamental and hybrids well suited to smaller spaces, there is something for every garden.

Wondering what species or cultivars might be right for your yard? The Tufts Pollinator Initiative, a group of scientists who are dedicated to pollinator conservation, has done some of the homework for gardeners.  They composed the informative table below highlighting many characteristics like preferred conditions, bloom time, height, and growth habits of Solidago widely available in the garden trade.3

Solidago sphacelata
Solidago caesia
Solidago rugosa ‘Fireworks’
Solidago speciosa
Solidago juncea

(Left to right, top to bottom) Examples of goldenrods with clumping habits that translate well to the home landscape: autumn goldenrod (S. sphacelata); blue-stemmed goldenrod (Solidago caesia); wrinkle leaf goldenrod (S. rugosa ‘Fireworks’); showy goldenrod (S. speciosa); and early goldenrod (S. juncea). (Image credits: Tom Potterfield CC BY-NC-SA 2.0 ; Scott Detwiler CC BY-SA 3.0; F. D. Richards CC-BY-SA 2.0; Dan Mullen CC BY-NC-ND 2.0; Dan Mullen CC BY-NC-ND 4.0)

Extend the season of colorful blooms in your landscape with goldenrod–an ecologically sound choice for any garden.

Notes

1–https://hgic.clemson.edu/native-notes-goldenrod/.

2–Interestingly there is a goldenrod whose flowers are creamy-white instead of yellow–the silver-rod goldenrod (Solidago bicolor).

3–https://sites.tufts.edu/pollinators/blog/

Resources and Additional Information

For general information on goldenrod, check out North Carolina State University’s Plant Toolbox site. There are also additional links to various species of the plant.

https://plants.ced.ncsu.edu/plants/solidago

Often people, unfortunately, mistake goldenrod for the allergy-inducing ragweed (Ambrosia spp.). Read Clemson Cooperative Extension’s informative fact sheet which outlines how these two plants share little other than bloom time.

Goldenrod & Ragweed

To see more images and suggestions for home-garden goldenrods, view Sea Grant’s video on these native plants.

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