Phytolacca americana, commonly known as pokeweed, is a herbaceous perennial plant that grows up to 3m tall. It is considered one of the most aggressive and weedy plants. The stem is showy, red-purplish, and branched about 10 cm wide.
It can be easily identified by its reddish-purple stems, large leaves, and dark purple to black berries.
Phytolacca americana Classification
- Domain: Eukaryota
- Kingdom: Plantae
- Phylum: Magnoliophyta
- Subphylum: Angiospermae
- Class: Dicotyledonae
- Order: Caryophyllales
- Family: Phytolaccaceae
- Genus: Phytolacca
- Species: Phytolacca americana
- Varieties: Phytolacca americana var. americana, and Phytolacca americana var rigida
- Common Names: American pokeweed, Common pokeweed, Pigeon berry, Pokeberry, Poke sallet, Poke, Dragonberry, and Garnet.
Nativity and Distribution
Pokeweed is native to north, central, west, and southern parts of the United States. Today it can also be found in:
- Asia
- Europe
- Africa
- Australia
Physical Characteristics
- Leaves: Alternate, broadly ovate, with smooth to slightly wavy leaf margins.
- Fruits: Dark purple to black berries.
- Stems: Showy herbaceous reddish-purple stems.
- Flowers: White or green with 4-5 sepals and no petals.
- Roots: Tap root system.
Phytolacca americana is a herbaceous perennial plant that grows up to 3m in height. It is easily recognizable by its showy reddish-purple stems, large leaves, and drooping dark purple to black berries.
Stems are smooth, robust, and woody at the base when mature. They exhibit an upright bushy growth habit and are thick in diameter about 2.5 to 5 cm wide. The leaves are simple, alternate, broadly ovate about 17 cm wide and 30 cm long with smooth to slightly wavy margins.
The upper surface is green while the underside is pale green with reddish tints along the veins and has a distinct odor when crushed.
Pokeweed produces green or white flowers about 2 cm wide that develop in clustered racemes. The perfectly radially symmetrical flowers have 4-5 sepals and no petals. Flowering occurs between July and September.
The seeds are black, oval in shape, about 2-6mm in diameter with a hard glossy exterior to help them withstand harsh environmental conditions.
Reproduction, Dispersal, and Life Cycle
- Life Cycle: Perennial
- Seeds: Can produce 1,500 to 7,000 seeds
- Climate: Temperate climate
- Dispersal: Birds, water and transport of contaminated soil
Phytolacca americana behaves as a perennial and reproduces by seeds. One isolated plant can produce between 1,500 to 7,000 seeds which are generally highly viable.
Seeds germinate on the soil surface or in shallow soil (up to ¼ inch deep). Seeds at greater depth can remain viable for 40 years.
Seeds are mainly dispersed by birds who ingest the berries and excrete the seeds in new locations. Secondary dispersal can also occur by water or transport of contaminated soil through erosion or human activities like landscaping and gardening.
Similar Plants
- Phytolacca octandra
- Fallopia japonica
- Heracleum mantegazzianum
Uses
- It is grown as an ornamental for the striking appearance of the berries.
- It is used as a border plant because of its imposing structure.
- Young leaves are consumed as vegetables and as a topping in salads such as poke salad.
- It is used as a traditional medicinal plant for treating ailments like respiratory issues and skin disorders.
- The berries are processed to make pink dye.
Impact on Farms and Environment
P. americana is an invasive weed in cropping systems and landscaping settings because of its aggressive and vigorous growth. It competes for important resources and space, reducing crop quality and yield.
Some of the commonly affected crops include corn, soybean, and cotton. It is also a host to pests like soybean cyst nematode and is highly susceptible to the contagious mosaic virus.
It is also a weed of old fields, pastures, forest edges, wastelands, under power lines, and rights-of-ways, negatively impacting native biodiversity and impeding movement.
Pokeweed is a poisonous plant. It is toxic to humans and if abrasion occurs, it can cause symptoms like vomiting and diarrhea. It is also toxic to livestock and when ingested it can cause dyskinesia or even death, making it a potential hazard in farmyards where livestock are present.
Control
- Mechanical control: Hand pulling, digging, cutting, and tillage
- Chemical control: Herbicides like Glyphosate, 2,4-D, Triclopyr, Imazapyr, and Dicamba
The best way to prevent a pokeweed infestation is to monitor seedlings in areas where birds often perch such as under power lines, on fence rows, and under tree canopies and implement an immediate removal strategy.
If the infestation has already occurred, it’s best to remove the small plants from the roots by hand-pulling. You can also consider a homemade weed killer to achieve similar results.
However, digging can provide better control when the plant becomes established and develops an extensive root system. You only need to wet the ground around the plants and dig them out from the roots.
Repeated cutting below the root crown depletes its energy storage, preventing regrowth. Intensive tillage can also help limit pokeweed growth in agricultural farmlands.
Several selective and non-selective herbicides including 2,4-D, Dicamba, and Glyphosate can be used depending on the type of crop and size of the weed.
Consult a local expert for more information on the best herbicide to use on your farm or landscape.
Biological control agents against P. americana are yet to be developed.
Lead Editor for Insight Weeds.