Oxypolis rigidior aka Cowbane

Oxypolis rigidior belongs to the carrot family, Apiaceae. It is a perennial, a plant that lives for years. Its common names include cowbane and pig potato. Kew says it is native to southeastern Canada. Its native range also spans the central and eastern United States. Kew places it in temperate climates, where heat and cold stay mild. The RHS says it is not native to Britain or Ireland. These records show its origin, not everywhere people grow it. The sources give no more detail on its wild habitats.

Chicago Botanic Garden says cowbane grows in an upright form. Like Kew, it lists the plant as a perennial. The records give no height or spread at full size. They thus give no basis to judge its garden size. Nor do they describe its leaves, stems, or roots. The common names alone tell us nothing about these parts. This account does not cover any named cultivar, or bred form. The garden record covers the species itself.

The plant has white flowers. Chicago Botanic Garden lists bloom times from July through October. It groups July with August, then September with October. These dates span both summer and fall. The entry does not say if blooms last through those months. Nor does it describe the flower shape or fruit. The sources do not name what pollinates the flowers. They do not say how the plant makes seeds. White blooms and upright growth are its main recorded garden traits.

Chicago Botanic Garden calls for full sun and moist soil. These are the clearest facts on growing it here. Its profile lists USDA hardiness zones 2–11. This wide range comes from just one archived garden entry. The page says updates stopped before February 2022. It gives no soil texture, soil pH, or plan for watering. The sources call for moist soil. They do not show if it copes with drought or standing water. They give no review of pests, disease, or care tasks. Nor do they confirm any safe food use or toxic effects. Neither common name tells us if it is safe to eat. The sources describe a long-lived plant that needs sun and moist soil. Yet they leave many points on care and safety unclear.