Oxalis stricta, called the common yellow woodsorrel (or simply yellow woodsorrel), common yellow oxalis, or upright yellow-sorrel is a herbaceous plant.

O. stricta is native to North America and East Asia and has been introduced elsewhere, especially in Europe. It was not documented in Michigan before the 1890s.

It tends to grow in woodlands, meadows, and in disturbed areas as both a perennial and annual. and generally requires dry or moist, alkaline soils, preferring sandy and loamy dirt to grow in. It requires well-drained soil and can grow in nutritionally poor grounds.

Commonly considered a weed of gardens, fields, and lawns, it grows in full sun or shade.

Upright yellow woodsorrel is an annual or short-lived perennial plant that has short rhizomes, but never has bulbs. The alternate leaves of this plant are divided into three distinctively heart-shaped leaflets (a typical trait of other species of Oxalis) that can grow up to 2 cm wide. These leaves curl up at night (exhibiting nyctinasty), and open in the day to perform photosynthesis.

The flowers of the plant are hermaphroditic, blooming from July to October.

The mature seed capsules open explosively when disturbed (a very similar trait to that of the mature seed capsules or fruits of plants found in the genus Impatiens) and can disperse seeds up to 4 meters (about 13 feet) away.

Erect when young, this plant later becomes decumbent as it lies down, and branches regularly.