Oxalis grandis aka Great Yellow Woodsorrel

Oxalis grandis is known as great yellow wood-sorrel. It belongs to the wood-sorrel family, Oxalidaceae. Its native range covers the eastern United States. It grows in woods, including sandy sites and alluvial soils. Kew classes it as a perennial or rhizomatous geophyte. Other sources describe both annual and perennial growth.

Plants reach 1–2 feet [0.30–0.61 metres] tall and wide. The upright stems are green, round, and lack scent. Long leaf stalks bear three leaflets. Each leaflet has an upside-down heart shape and smooth edges. A fine maroon line borders each leaflet. Leaves may grow along stems or form a basal rosette. Underground stems send out roots and new shoots. This growth allows patches to extend beyond one plant's stated width.

The flowers are yellow, with red marks at each petal's base. Each bloom has five petals and five sepals. Flowers reach about 0.08 feet [0.025 metres] across. NC State gives May to June as the flowering season. Plants For A Future gives a longer May to September season. Green capsules follow the flowers. Ripe capsules split open and scatter their seeds. The unripe fruit has a sour taste.

Light guidance differs between the sources. NC State lists full sun; Plants For A Future recommends shade or partial shade. Both describe soil conditions that allow some dryness. Plants For A Future favours moist to slightly dry ground. NC State lists well-drained clay, loam, sand, and humus-rich soil. It also lists neutral soil and USDA zones 5–7. Growth is fast. Woodland ground cover is one use, including beneath shrubs. NC State also lists containers, native gardens, and naturalized areas. Plants For A Future reports no weed potential. NC State flags the plant as weedy, so reports differ.

The leaves taste sharp because they contain oxalic acid. Plants For A Future lists raw or cooked leaves as edible. It also lists raw flowers, but urges small portions. NC State includes seeds and roots among edible parts. This does not make the whole plant safe in quantity. All parts carry some toxic risk when eaten. NC State rates the risk as low and flags pets and horses. Large amounts may cause serious harm. People prone to kidney stones or gout should take extra care. Cooking reduces the leaves' oxalic acid content. Plants For A Future also reports using leaf juice on linen stains.