Native to most of Europe, Treacle Mustard (Erysimum cheiranthoides) can be seen growing wild on other continents as well. It is considered a weed in most areas. Because its seeds taste so bitter, a grain crop contaminated with treacle Mustard seeds is effectively ruined. Livestock can become ill if these plants grow in their grazing area.
I. Appearance and Characteristics
Erysimum cheiranthoides, the treacle mustard, wormseed wallflower, or wormseed mustard is a species of Erysimum. Like other Erysimum species, E. cheiranthoides accumulates two major classes of defensive chemicals: glucosinolates and cardiac glycosides.
It was formerly described by the Swedish botanist Carl Linnaeus in his seminal publication ‘Species Plantarum’ in 1753, on page 661.
It is commonly known as treacle-mustard, or wormseed wallflower. The treacle mustard name came from the Greek word ‘theriaki’ meaning antidote to poisonous bites as the plant was thought to have healing properties. The name ‘wormseed wallflower’ arose from the seeds of the plant being made into treacle, to treat intestinal worms in children.
It is a herbaceous, annual plant similar in appearance to many other mustards, growing an erect stem 15–100 cm (5.9–39.4 in), (rarely 150 cm) tall. The leaves are lanceolate to elliptic, 2–11 cm long and 0.5–1 cm broad, with an entire to coarsely toothed margin. It blooms in summer, between June and August. The flowers are bright yellow, 5–12 mm diameter, and produced in an erect inflorescence. Later, it produces a slender cylindrical capsule, 1–3 cm (rarely 5 cm) long, containing several small, pale brown or dark brown seeds.
Erysimum cheiranthoides is native to temperate areas of Europe and Asia.
It is found in Asia within China (in the provinces of Heilongjiang, Jilin, Nei Monggol and Xinjiang), Japan, Korea, Mongolia and Siberia. In Eastern Europe, it is found in Belarus, Estonia, Latvia, Lithuania, Moldova and Ukraine. In middle Europe, it is found within Austria, Belgium, the Czech Republic, Germany, Hungary, the Netherlands, Poland, Slovakia and Switzerland. In Northern Europe, in Denmark, Finland, Norway, Sweden and the United Kingdom. In Southeastern Europe, within Bosnia and Herzegovina, Bulgaria, Croatia, France, Romania, Serbia and Slovenia.
It is also widely naturalised outside of its native range, from New Zealand, other parts of Europe, to North America (including parts of Canada), and Argentina (in Tierra del Fuego).
II. How to Grow and Care
Treacle Mustard is a robust, adaptable species known for its low-maintenance care requirements. Treacle Mustard thrives with minimal watering once established, making it relatively drought-tolerant. Special care should be taken to avoid overwatering, as this can lead to root rot. It’s easy care level makes treacle Mustard a suitable plant for both novice and experienced gardeners seeking minimal care challenges.
Sunlight and Soil
Treacle mustard prefers full sun conditions and well-draining soil.
Watering
Originating from temperate regions, treacle Mustard is accustomed to moderate moisture levels and can tolerate brief periods of dryness. Its native climate has endowed it with a preference for consistent but not excessive watering, aligning with its natural rhythm of receiving rainfall weekly. Accordingly, treacle Mustard thrives best when watered once every week. As an outdoor plant often subject to the whims of weather, treacle Mustard displays resilience in various rain conditions, making it well-suited for gardens where precipitation patterns are unpredictable.
Fertilizing
Treacle Mustard thrives best in full sun conditions where it can receive uninterrupted daily light exposure. Should these conditions be met, the plant will likely flourish, showing vigorous growth and optimal health. However, treacle Mustard exhibits a certain degree of adaptability and can tolerate partial sun, though this may influence its robustness and flowering potential. In inadequate light, treacle Mustard may demonstrate leggy growth or reduced vitality. Outdoors, it fares well in locations that provide ample sunlight. There are no particular indoor recommendations, as treacle Mustard is primarily an outdoor species. Treacle Mustard ‘s light-related adaptability does not involve significant changes in leaf coloration or structure.
Transplanting
The prime time to transplant treacle Mustard is from the renewal of spring until the seasons are in full swing, offering the ideal temperature conditions treacle Mustard thrives in. Select a sunny spot with well-draining soil to encourage robust growth. Gentle handling and minimal root disturbance will aid successful establishment.
III. Uses and Benefits
- Medicinal uses
Cardiac glycosides, which are abundant in E. cheiranthoides, have been used for treating heart disease and other ailments in traditional and modern medicine. However, E. cheiranthoides is not a commonly used source of these compounds. Nevertheless, E. cheiranthoides has been used as an herbal remedy in traditional Chinese medicine. European herbalists in the 16th century, used the plant as a remedy for insect and animal bites. The common name wormseed wallflower comes from the use of E. cheiranthoides in treating intestinal worms.
- Use as a model organism
Because Erysimum is in the family Brassicaceae, it has been proposed that many of the genetic resources that already exist for Arabidopsis thaliana (an extensively studied model organism) can be used with Erysimum to aide in genetic analysis, making this genus particularly attractive for studying the cardenolide biosynthetic pathway. E. cheiranthoides itself is diploid and has a relatively small genome (~200 Mbp across 8 chromosomes), can be grown from seed to seed production as fast as 10 weeks, and performs well in a laboratory setting.
The genome of E. cheiranthoides variety Elbtalaue has been sequenced. As E. cheiranthoides has many genetic similarities to A. thaliana, it is likely that techniques for genetically modifying A. thaliana and related research methods will also work for E. cheiranthoides. Mutated isolates of E. cheiranthoides with altered cardiac glycoside content have been identified.
