Portulaca oleracea (Common Purslane, also known as Verdolaga, Pigweed, Little Hogweedor Pusley), is an annual succulent in the family Portulacaceae, which can reach 40 cm in height. About 40 varieties are currently cultivated. It has an extensive old-world distribution extending from North Africa through the Middle East and the Indian Subcontinent to Malaysia and Australasia. The species status in the New World is uncertain: it is generally considered an exotic weed; however, there is evidence that the species was in Crawford Lakedeposits (Ontario) in 1430-89 AD, suggesting that it reached North America in the pre-Columbian era. It is naturalised elsewhere and in some regions is considered an invasive weed. It has smooth, reddish, mostly prostrate stems and alternate leaves clustered at stem joints and ends. The yellow flowers have five regular parts and are up to 6 mm wide. The flowers appear depending upon rainfall and may occur year round. The flowers open singly at the center of the leaf cluster for only a few hours on sunny mornings. Seeds are formed in a tiny pod, which opens when the seeds are ready. Purslane has a taproot with fibrous secondary roots and is able to tolerate poor, compacted soils and drought.
When stressed by low availability of water, purslane, which has evolved in hot and dry environments, switches to photosynthesis using Crassulacean acid metabolism (the CAM pathway): at night its leaves trap carbon dioxide, which is converted into malic acid (the souring principle of apples), and in the day, the malic acid is converted into glucose. When harvested in the early morning, the leaves have 10 times the malic acid content as when harvested in the late afternoon, and thus have a significantly more tangy taste.
Known as Ma Chi Xian (pinyin: translates literally as “horse tooth amaranth”) in Traditional Chinese Medicine, it is used to treat infections or bleeding of the genito-urinary tract as well as dysentery. The fresh herb may also be applied topically to relieve sores and insect or snake bites on the skin. Eating purslane can dramatically reduce oral lichen planus.