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Lepidium draba
⚠️ PROHIBITED NOXIOUS — also called Whitetop. A 30–60 cm perennial from Eurasia with grey-green foliage and flat-topped clusters of small white four-petaled flowers giving large infestations a snow-covered appearance in late spring. Extremely aggressive rhizomatous spread plus heavy seed production. Serious threat to Alberta's rangeland and crop production. Allelopathic — suppresses other plants chemically.
Quick Facts
Distribution
Scattered in southern Alberta, spreading northward
Light
Full sun
Bloom Time
May–June
Soil
Adaptable — prefers disturbed alkaline soils
Water
Low to moderate
Use Caution— Mustard-family glucosinolates — can cause GI upset and may flavour milk/meat from livestock grazing it
Growing & Cultivation
Propagation
DO NOT PROPAGATE. Control: repeated herbicide treatments over 3+ years; hand-pulling futile due to deep rhizomes.
