Horticulture specialists for the University of Arkansas Division of Agriculture's Cooperative Extension Service are experts at identifying "mystery plants."
Arkansans can send us a photograph and ask, "What's that plant?"
Some mysteries are easy to solve. We tend to get the same questions over and over.
Here are some of the plants we're most often asked to ID.
Empress tree, Royal Paulownia (Paulownia tomentosa): We see this tree in many, many pictures submitted for identification. When young, it has huge leaves. It grows rapidly as a young tree. Then things slow down and it begins to bloom, with purple blooms. Following the flowers, it sets woody seed capsules, which disperse seeds far and wide. Invasive tree, weak wooded, not recommended for those who want a long-lived shade tree.
Arum seed pods are another common question. Oftentimes gardeners come across a lone stem full of orange/red seeds jutting out of the ground with no foliage in sight. In landscapes, these are usually a perennial ornamental called Italian arum. In the wild, such seed stalks are usually from Jack-in-the-pulpit or Green Dragon. All of these related plants produce foliage in the cooler months. In early spring they have spathe-like blooms that produce the seed stalks. As temperatures heat up, the foliage disappears leaving behind the seed pods, which turn from green to orange.
Peppervine (Ampelopsis arborea) is a very common weed across Arkansas. The prolific grapelike vine produces compound leaves, inconspicuous pale green flowers followed by small fruits, which ripen in the fall. Birds do eat them, and then they drop the seeds, which helps disperse the vines. So it is a native vine, but prone to becoming invasive. The fruits contain calcium oxalate, which can be an irritant to humans. Some sources list the plants as poisonous, while others actually eat them. I would recommend not eating the plant and eradicating it from your garden before it takes over.
Beautyberry and French mul-berry are the common names for Callicarpa americana, a wonderful native shrub for the garden. It thrives in full sun to moderate shade. This deciduous plant has small pale purple blooms in the summer that are not showy, but the resulting berries put on a real show come fall. The plants are covered in show-stopping, bright purple berries from early fall through frost. While purple is the most common form, there are pale lavender- and white-berried forms as well.
Castor bean is the common name for Ricinus communis, an annual, tropical-looking plant with large leaves and bizarre seed pods. It is a member of the Spurge or Euphorbia family. The seeds are extremely poisonous, so keep plants out of the reach of children (or trim off the flowering spike to prevent seed set). The toxin in castor seeds is ricin. As a child you may have been given castor oil, which also comes from this plant. Since the toxin does not occur in the pure oil, castor oil can be consumed and has been used medicinally. Although an annual plant, it grows up to 6 feet or more in one growing season and can make quite a statement in full sun.
Chinese tallow tree or popcorn tree are the common names for the highly invasive Sapium sebiferum or Triadica sebifera tree (Latin names have changed, but both are used). Native to China, it was introduced to the United States in the early 1900s as an attempt to use the oil to produce soap. Short-lived, brittle trees up to 60 feet tall, they produce a copious amount of seeds and can begin reproducing as young as 3 years old. The resulting fruits are white and look like puffed popcorn, thus the common name. Cold winters limit its spread in northern Arkansas, but it has been a problem in the southern part of the state.
Chinese parasol tree or varnish tree are the common names for Firmiana simplex, a deciduous tree with a tropical-like look growing in Arkansas. Native to Southeast Asia, the tree is hardy to temperatures of 10 degrees or so. This deciduous tree, which has smooth, green bark even at maturity, produces large, palmate leaves. It grows up to 35 feet tall. In late summer it is covered in clouds of yellowish-green flowers that give way to leathery seed capsules.
Groundsel bush or Baccharis halimifolia is a native shrub found commonly in the southern half of Arkansas. There are separate male and female plants. The female plants have showy white "flowers" that are actually feathery seed pods similar to what a dandelion produces. Groundsel is a bit too aggressive to be used as a shrub in the home landscape.
Hyacinth bean (Lablab purpureus also sometimes called Dolichos lablab) is an annual ornamental vine and a member of the bean family. The fast growing vines can reach 20 feet in a single season. Vines climb by twining around a support and can cover a chain-link fence quickly. The purple-leafed form is most often grown in gardens, but green-leafed selections are available. From midsummer through fall, they produce an abundance of purple flowers (a white form is also available) followed by deep magenta seed pods. Save seeds to plant next year in your sun garden.
Hymenocallis is the genus for a perennial bulb plant commonly called spider lily or Peruvian daffodil. Many species exist and most are native to the United States, Mexico and Central America. They resemble a white daffodil because of the central cup, but then they have long, spidery-thin petals that stretch away from the cup. They are tough and low-maintenance bulbs that will perform well in average garden soil.
Indian pink (Spigelia marilandica) is a native perennial wildflower that occurs in moist woods and streambanks. It produces trumpet shaped, upward facing blooms that are red on the outside and yellow on the inside. It does best with morning sun and afternoon shade. It is a favorite of hummingbirds and butterflies.
Jewels of Opar (Talinum paniculatum): The original plant is green-leafed, but a newer variety, "Limon," has lime green foliage and wiry stems of tiny hot pink flowers, followed by bronzy red, little, round seedpods. It grows well in full sun and is quite drought tolerant once established. It only grows about 10 to 12 inches tall, but it can reseed itself.
Jujube or Ziziphus jujuba is sometimes called Arkansas date because it is a small fruiting tree with mature fruit similar to a date. This deciduous tree can grow 30 feet or more and often has thorns on the stems. The immature fruit is green, but as it ripens it goes through a yellow-green stage with mahogany-colored spots appearing on the skin. The fully mature fruit is entirely red. Shortly after becoming fully red, the fruit begins to soften and wrinkle. The fruits can be eaten after they wrinkle, but most people prefer them during the interval between the yellow-green stage and the full red stage.
Turk's turban or Turk's cap are common names for Malvaviscus arboreus. This perennial member of the hibiscus family begins to bloom in midsummer through fall. The deep orange flowers are swirled petals that never open, but produce long, protruding stamens. It is an old fashioned, "pass-along" plant and a favorite of butterflies and hummingbirds. This plant is also considered deer resistant.
Fallopia japonica (originally Polygonum cuspidatum) is commonly called Mexican bamboo, Japanese knotweed or fleece flower. The variegated form became popular as a garden perennial, but gardeners need to beware. It spreads easily from underground runners.
Another runner that blooms in the shade is Mexican hydrangea, aka Cashmere Bouquet or Rose Glory Bower (Clerodendrum bungei). The plant produces beautiful pinkish purple clusters of lightly fragrant blooms on dark, glossy foliage. But in good soil, it will spread quickly.
Pomegranate: Punica granatum is a plant that has made a quick comeback. In the South, it was a pass-along plant prized for its double orange blooms on a large shrub. Rarely did these plants produce any edible fruits. Today, large fruiting varieties are being planted in gardens across the region.
In late summer, Arkansans often send us some weird seed pods to identify. They are prized by craft folks who like to use these seed pods from a weed whose common name is Unicorn plant or Devil's claw -- Proboscidea louisianica. The flowers are actually quite nice, but you probably don't want the plant in your garden.
Poison ivy vs. Virginia creeper: These two common weeds/native plants are often mistaken for each other. Poison ivy is a noxious weed that causes horrible rashes in many people. Leaf shape can vary, but it always has three leaves with the bottom two leaflets touching and the top with a slightly extended petiole. Virginia creeper has three to five leaflets depending on the vine's age, but they are all attached at the same point. It is a native vine that can become aggressive in good growing conditions.
Janet B. Carson is a horticulture specialist for the University of Arkansas Cooperative Extension Service.
HomeStyle on 08/18/2018