Aufrechter Sauerklee

<em>Oxalis stricta</em>, the common yellow oxalis or upright yellow wood sorrel, is an annual or perennial herbaceous plant in the family Oxalidaceae. It is native to North America but has been widely naturalized across Europe, Asia, Australia, and other temperate regions, where it occurs as a common weed of gardens, cultivated land, roadsides, and disturbed ground. The plant typically grows 10–40 cm tall and produces trifoliate clover-like leaves with three heart-shaped leaflets that fold downward at night or under bright sunlight, a response known as nyctinasty. Bright yellow five-petaled flowers are borne on slender stalks from spring through autumn. Seed pods explode at maturity to disperse seeds over short distances, contributing to the plant's effectiveness as a colonizer. Biological traits such as precise average lifespan and body measurements remain poorly documented in consolidated literature. <em>Oxalis stricta</em> contains oxalic acid, which gives the plant a sour taste and can be mildly toxic to livestock in large quantities. It provides nectar for small pollinators. The species has not been formally evaluated for IUCN conservation status but is abundant and widespread globally, with no conservation concerns.