Purple Star of Bethlehem (Ornithogalum umbellatum) is a perennial bulbous plant. Its star-shaped flowers are typically bright white on their upper surface. While the common name suggests purple, the flowers often feature green or purplish stripes on the undersides of their petals. Native to Europe, North Africa, and Western Asia, it was initially introduced to North America as an ornamental plant.
Identifying Purple Star of Bethlehem
The plant grows from an ovoid bulb, approximately 0.5 to 1.5 inches in length, producing a rosette of basal leaves. These leaves are grass-like, linear, dark green, and often feature a prominent white or pale green stripe down their center. They can grow 6 to 12 inches long and tend to curve upward from the base before bending downward.
Leafless flower stalks emerge from the center of the leafy rosette, reaching heights of up to 1 foot. Each stalk bears clusters of 3 to 10 star-shaped flowers, usually about 0.5 to 0.75 inches in diameter. Each flower consists of six bright white tepals (three petals and three sepals), with a characteristic green stripe on their outer side. The flowers typically open during sunny periods, often around noon, and close at sunset or on cloudy days, a trait that has earned them common names like “nap-at-noon.”
Is Purple Star of Bethlehem Invasive
Purple Star of Bethlehem is an invasive species in many regions due to its aggressive growth. It quickly spreads and forms dense colonies, outcompeting native plants in various environments, including gardens, lawns, pastures, and natural areas like meadows and stream banks. Its prolific reproduction is a primary factor in its invasiveness, mainly through numerous underground bulblets (offsets) around the parent bulb.
These bulblets are very hardy; even small pieces left in the soil can generate new plants, making manual removal challenging. While seed production is less common in North America, the plant produces three-lobed seed capsules containing several black seeds, contributing to its spread. Its ability to reproduce effectively from bulbs and, to a lesser extent, by seed allows it to rapidly colonize new areas, displacing existing vegetation. Some states and regions classify it as a noxious weed or invasive species, highlighting its potential ecological threat.
Toxicity of Purple Star of Bethlehem
All parts of the Purple Star of Bethlehem plant are toxic if ingested, with the bulbs containing the highest concentration of harmful compounds. These compounds are cardiac glycosides, which directly affect heart function. Ingestion can lead to a range of symptoms in humans and animals, varying in severity based on the amount consumed and the individual’s sensitivity.
Symptoms of poisoning in humans and pets may include gastrointestinal distress such as nausea, drooling, vomiting, and diarrhea. More severe effects can involve cardiovascular problems like abnormal heart rhythm and rate, shortness of breath, and weakness. In livestock, clinical signs include depression, bloating, and a rapid pulse, with death potentially resulting from respiratory failure in severe cases. Contact with the plant’s sap can also cause skin irritation.
Managing Purple Star of Bethlehem
Managing Purple Star of Bethlehem requires persistent effort due to its robust reproductive capabilities. Manual removal is often effective for small infestations, but requires digging deeply to ensure all bulbs and bulblets are extracted. Any missed bulb fragments can quickly sprout new plants, so careful sifting of the soil is recommended. Discarding removed plant material, especially bulbs, in the trash rather than compost to prevent further spread, as they can survive and sprout in compost.
Cultural practices also help manage the plant. Mowing prevents seed set by removing flowers, though this alone is insufficient for control as it does not address the bulbs. Promoting dense, healthy turf or desirable plant growth helps suppress its establishment. Ensuring good soil drainage discourages its growth, as it prefers moist conditions.
For chemical control, certain herbicides have shown varying effectiveness. Products containing sulfentrazone, carfentrazone, or 2,4-D provide control of the foliage. However, many herbicides only affect the top growth, and repeat applications may be necessary over several seasons to deplete the underground bulbs. Non-selective herbicides like glyphosate are used for spot treatments, but they may also harm surrounding desirable vegetation. Always follow label directions carefully for any chemical application to ensure safety and effectiveness.