��������

If America is a melting pot, so are her flower gardens—to an extent that few of us realize. Ever since the first Europeans landed on our shores, foreign plants have come along, intentionally or otherwise. 

Many of these non-native plants grow abundantly across the entire continent today, naturalized along roadsides, fields, forest edges, and other disturbed sites around the country. 

Common Non-Native Plants

Many pretty plants are so common in gardens that you wouldn’t know they were actually stowaways! Here are a few non-native plants that are part of our heritage today …

Daylilies

Orange-red daylilies arrived in Europe from China during the 17th century and were widely cultivated in the New World. Today, persistent patches of Hemerocallis fulva (“beautiful for a day”) blaze in deserted American cellar holes and form brilliant borders along country roads. Hemerocallis fulva is commonly called tiger lily, roadside lily, outhouse lily, ditch lily, or tawny daylily.

They are a living testimony to human history, for Hemerocallis spreads almost solely by division. Sometimes, it’s transplanted by gardeners. Sometimes, it sends out underground rhizomes. Sometimes, it appears unexpectedly, the offspring of bits and pieces torn and tumbled along by snowplows or road graders. It has often been used for erosion control; its thick tuberous roots do well to hold soil in place.

In ancient times, the daylily was valued as both food (baked into a custard with rich milk, butter, and salt) and medicine (in the form of a poultice applied to burns). Daylily buds are edible, but today, we use the proud plant to hold soil on hillsides and brighten those corners of the garden where a rugged pest- and disease-resistant perennial is needed.

This daylily species quickly escaped from gardens to the wild. In the U.S., it has become naturalized in 42 states. It spreads by 12-inch-long underground stems, or stolons, not by seed. Its network of stolons and roots makes it difficult to fully dig out; any bit of root left in the ground can generate a new plant. It is now listed by a number of states as an invasive plant.

Daylilies do attract some pollinators, though their value is minimal; they’re not a host for butterfly or moth larvae to feed future pollinators, and the nectar is primarily accessible and suitable to long-tongued generalist adult insects only.

The hybrid daylilies sold at garden centers are clump-forming, and they set seed; they are not stoloniferous like standard daylilies. (“Stoloniferous” refers to how the plant spreads. When the tip of a branch touches the ground, it can root and start another plant.) You should not fear that they will take over your garden or escape into wild areas.

See our article on growing daylilies.

Foxglove

is native to Europe, where it has been grown for centuries. When English and German settlers came to America, they brought foxglove seeds and scattered them on the edges of their homesteads. It did not take long for this plant to escape the coastal settlements and begin the trek westward. In 1809, when John Bradbury set out to collect wildflowers in the newly acquired Louisiana Purchase, he could trace the paths of the pioneers in the trails of foxglove that they had left behind. 

Common Foxglove, a tall biennial herb, is now found in gardens and has naturalized to spread to roadsides, fields, forest edges, and other disturbed sites around the country. The flowers bloom during the summer months, usually June and July. In the first year, the plant produces the foliage, but the masses of purple bellflowers don’t generally come until the following year. Arranged in a showy, elongated cluster, each flower is tubular and pendant. The flowers are typically purple, but some plants, under cultivation, may be pink, rose, yellow, or white.

As early as 1768, foxglove was known to be a potent heart medicine. Its leaves and seeds contain digitalis, making it the primary source of the eponymous commercial drug.

Note: Due to the cardiac glycoside digitoxin in the leaves, flowers, and seeds of this plant, it is highly poisonous to humans and a danger to animals that may try to eat it. Even the water that cut flowers are placed in is toxic.

On the bright side, foxglove is a pollinator magnet! The petals are fused together to produce the tubular flower—the lower lip of which acts as a landing pad for pollinators. Twenty to 80 individual flowers can be found loaded up on each stalk, typically only on one side.

• Honeybees, bumblebees, butterflies, and moths love this plant.
• So do hummingbirds! See more plants that attract hummingbirds.

Unfortunately, the common foxglove is an invasive species in some regions. While it provides a benefit to pollinators, it’s perhaps not the most ideal plant to select for a wildlife garden because of its toxicity, as well as its ability to escape easily and spread. The small fruit are capsules in the shape of an egg, and each plant can produce up to 5,000 seeds!

Forsythia

��ǰ�����ٳ󾱲�’s neon yellow sprays have become a ubiquitous sign of spring across much of North America. Long before it came here and before it had been introduced in Europe, it grew wild on the South China coast. 

It was not until the mid–18th century that fortune—Robert Fortune, specifically—found it. A plant hunter for England’s Royal Horticultural Society, Fortune disguised himself in native garb and pigtails to scour the country for new plants. In 1846, he carried a sample of forsythia (aka “golden bells”) to London, where it was named after William Forsyth, a founding member of the society and superintendent of the Royal Gardens at Kensington.

Forsythia made its way to America in about 1860, sailing from England to Massachusetts, although it did not appear in nursery catalogs until the end of the century. Today, it thrives on most of the continent, faring less well in the Gulf states and the Southwest.

One of the earliest bloomers, it’s easy to grow because it forgives nearly everything and will tolerate neglect and poor soil. It just needs to be cut back by 1/3 each year to keep it in a manageable state and blooming. Prune AFTER the blooms fade, not in late summer or fall, or you’re cutting off the buds for next year. 

Read how to force forsythias for early spring color.

The Native Plant Center lists forsythia as an invasive plant, though it’s not listed on the U.S. Department of Agriculture’s list.

• Forsythia is considered invasive by some, as it is stoloniferous (i.e., when the tip of a branch touches the ground, it can root and start another plant) and very difficult to remove. Some varieties of forsythia are sterile, so seeding is not usually the problem; it’s the root systems.
• Also, forsythia isn’t well integrated into the wood web. Native bees don’t use forsythia as a pollen source because it blooms too early, and bees co-evolve with native plants for food sources. For honeybees, the shape of the flower is probably prohibitive.

The shrub is not harmful on the level of Burning Bush (which spreads quickly to crowd out all native plants), but consider native alternatives if you’re planting anew.

The Native vs. Non-Native Question

Would you be surprised to learn that daffodils and tulips are non-natives, too? Or, that peonies and many state flowers are actually non-natives? Even tumbleweeds out on the Western range were introduced from elsewhere.

Yet, you certainly couldn’t call these long-established non-native plants “invaders.” They have a long heritage intertwined with our own. This challenges the idea of what a native plant is, and how we as humans can and are changing the natural environment. What is native, really?

One could argue that all plants are invasive. Think back to the Ice Age, when mobile glaciers ravaged a landscape that has since rebounded with plants that found their way there. Even if we humans do not remember when a plant was introduced, it could indeed be a non-native. Human memory is short, and sometimes, people equate popularity with history!

So, rather than get caught up in what year a plant was introduced, we might start with a question: Which non-native species are happy and getting along in the existing ecosystem—and which are truly harmful? (You might pose the same question for native plants as well.)

By harmful, we mean: Which non-native plants are bullies and invasive pests, crowding out native plants and severing the food chain (i.e., the insects, birds, and wildlife that depend on that native species)?

• Examples of harmful non-natives are: Purple Loosestrife (Lythrum salicaria), Japanese Honeysuckle (Lonicera japonica), Japanese Barberry (Berberis thunbergii), Burning bush (Euonymus alatus), Japanese Knotwood (Reynoutria japonica), Kudzu (Pueraria montana), and Field Bindweed (Convolvulus arvensis).

Whenever you consider a plant’s harmfulness, you need to consider your local ecosystem. For on-the-ground advice, contact your county cooperative extension. Here’s a list of state extension websites. 

Native Alternatives

For those who wish to learn about native alternatives to the plants featured in this article, here are some gorgeous, pollinator-friendly choices to explore!

�����ٱ���Բ��پ������&�Բ�����;�ٴ�…

…D����������� (Hemerocallis fulva)

•  
  This attractive flowering plant grows in full sun and well-draining soil. They prefer loose, sandy soil that isn’t overly fertile. Drought-tolerant, blanket flowers have a wonderfully long bloom season from early summer to early fall, growing to heights of 1 foot to 3 feet tall. The yellow-orange blooms add sizzle to the garden and attract nectar-seeking butterflies.

…Common Foxglove (Digitalis purpurea)

• 
  Show-stopping spikes of loosely spaced, white, violet, or deep purple, 2-inch-long tubular flowers line erect stems. Flowers bloom in June and are larger than other penstemon flowers.

…Forsythia (Forsythia spp.)

• 
  This is a broad, rounded shrub covered with fragrant yellow-green flowers in early spring. The flowers open before the leaves emerge and are held close to the branches. Aromatic light green leaves turn deep yellow-gold in fall. Spicebush is deer-resistant and an excellent host plant for the Eastern tiger swallowtail and the spicebush swallowtail butterflies. In the fall, birds feed on the small, brilliant red fruits formed on female plants. 

• Golden Currant, Clove Currant (Ribes odoratum)
  A thornless, loosely branched, arching shrub with blue-green, lobed leaves that turn a dull yellow in fall. In spring, golden yellow flowers appear and emit a strong, clove-like fragrance. Birds and small animals eat the black, round berries formed from June through August.

Local nurseries and other sources of landscaping plants still mostly sell non-natives. It’s really up to you as a gardener to make plant choices. If you wish to grow native plants and reduce the spread of invasive plants, contact your local county cooperative extension.