Hoary alyssum (Berteroa incana) is a flowering plant related to mustard that is native to Eurasia. Also known as false hoary madwort and hoary berteroa, it is considered an invasive weed. You can find them easily on roadsides and lawns.
I. Appearance and Characteristics
Berteroa incana is a species of flowering plant in the mustard family, Brassicaceae. Its common names include hoary alyssum, false hoary madwort, hoary berteroa, and hoary alison. It is a biennial herb native to Eurasia and it has been introduced to western Europe and North America. It is listed as an invasive noxious weed in some areas of United States and Canada.
Berteroa incana is typically a biennial herbaceous flowering plant, but it also grows as an annual to short-lived perennial. It is hairy, with flattened star-shaped and simple hairs. It produces one or more upright stems usually 30 to 80 centimeters tall, sometimes exceeding one meter. The basal leaves are up to 8 to 10 centimeters long. The leaves are hairy and grayish. The inflorescence is a dense raceme of flowers. The four white petals are roughly half a centimeter long and are tipped with two lobes. The fruit is a hairy silicle up to a centimeter long.
The plant is toxic to horses. Green and dry material is sometimes found in alfalfa feed. Signs of poisoning include lameness due to laminitis and leg edema, stiffness, fever, diarrhea, intravascular hemolysis, hypovolemic shock, premature birth, abortion, gut ulceration, edema of the kidneys, pulmonary edema, and calcium crystals in the urine. It can be fatal, but most horses survive with treatment. The toxic compound is not known.
B. incana is an invasive species of roadsides, railroads, farms and pastures, riverbanks, vacant lots, overgrazed rangelands, and lawns In the United States. It tolerates cold winters and hot, dry summer conditions. It thrives in poor soils with sand and gravel, more often in alkali soils.
It is a weed of alfalfa and clover forages, reducing their quality with its nutrient-poor herbage. It competes with native flora and reproduces continuously. It may reduce pollinators.
The plant is likely introduced to new areas when its seed is distributed with agricultural crop seeds.
II. How to Grow and Care
Hoary alyssum is a hardy plant that requires minimal maintenance, thriving in a wide range of environments. Key points include ensuring well-drained soil to prevent root rot and allowing space for growth since hoary alyssum can spread. Its adaptability makes it easy to care for, able to sustain itself in both poor soil conditions and various climates.
Sunlight
Hoary alyssum prefers direct sunlight but tolerates shade.
Watering
Thriving in its native habitat’s temperate climates, hoary alyssum has adapted to moderate moisture levels and exhibits a preference for consistent soil hydration without waterlogging. It maintains a delicate balance, tolerating brief periods of dryness but generally favoring a stable environment. Watering every week will sustain its health and mimic the natural precipitation it would receive outdoors. As an herbaceous plant often found in outdoor settings, hoary alyssum’s watering needs are closely tied to its active growing season, requiring more frequent irrigation during these peak growth times to support its development.
Soil
Hoary alyssum adapted to dry conditions on sandy or gravelly soils. It is found in overgrazed pastures, stressed meadows, roadsides and waste areas.
Fertilizing
Ensuring hoary alyssum thrives, opt for balanced nutrition fertilizers in spring for robust growth, switching to high-nitrogen feed during vegetative stages. Fertilize monthly at quarter strength to nourish without overfeeding. Fertilizing bolsters health and flowering but avoid excess application to prevent foliage burn. In cooler months, reduce frequency as hoary alyssum’s growth slows. Wear gloves when handling fertilizer and evenly distribute around the base, keeping clear of foliage. Seasonal adjustments and careful application promote hoary alyssum’s vitality.
Pruning
Hoary alyssum should be mowed or treated with herbicides before it flowers and forms seeds. Left to its own, Hoary alyssum is an invasive weed.
Propagation
Hoary alyssum propagation typically occurs through sowing during Spring. This plant propagates relatively effortlessly, with successful germination indicated by emerging seedlings. Adequate moisture and well-draining soil can aid in successful propagation.
Transplanting
To nurture hoary alyssum’s vigor, transplanting thrives best in the awakening green of early to mid-spring. Choose spots bathed in sun to partial shade, ensuring free-draining soil. Gently nestle hoary alyssum into its new home for robust growth.
III. Uses and Benefits
It is sometimes considered an ornamental plant good for landscaping purposes. It is planted to cover waste ground at mining sites and in urban areas in Europe.
