Common purslane

Common purslane is an annual succulent herb, usually prostrate and then ascending, 10–40 cm long and much branched from the base; a strong taproot with many fibrous roots allows it to tolerate drought and poor soils. The stems are smooth, not jointed, and range from green to red or purple. The leaves are alternate (sometimes nearly opposite), with short petioles and flat, fleshy obovate-to-oblanceolate blades 1–2.5 cm long and 0.6–1.5 cm wide, with rounded or slightly notched tips and a glossy upper surface. The small bisexual flowers are borne in clusters of 2–30 at the branch tips or leaf axils; there are 2 sepals, 5 yellow petals (sometimes 4–6) 4–7 mm long, 7–15 stamens and 4–6 stigmas; flowers usually open only in the morning and then wither. The fruit is an ovoid capsule 3–5 mm long that opens by a horizontal lid (circumscissile); the seeds are minute, glossy black, kidney-shaped and 0.6–1.2 mm long, with a tuberculate surface. It flowers and fruits in the warm season (almost year-round in Vietnam) and is regarded as a weed in many places.

Purslane is an almost cosmopolitan species. According to Plants of the World Online (Kew POWO), the populations regarded as native are concentrated in the Old World — the Mediterranean basin and southern Europe, North and tropical Africa, the Middle East and South Asia (Pakistan, India); long ago it spread and became naturalised in the Americas, Oceania and many islands. It is a species complex with many described forms and varieties or subspecies, which makes the precise native range difficult to define; many sources still treat it as native in parts of southern Europe and Asia as well. In Vietnam purslane grows wild throughout the lowlands, along roadsides, in fields, gardens and bare ground, and is also cultivated as a vegetable; it prefers sunny spots and tolerates light to heavy, nutrient-rich or poor soils.

Chemically, purslane stands out as the richest known leafy-vegetable source of omega-3 fatty acids: following Simopoulos and Salem (1986) in the New England Journal of Medicine, it is a “terrestrial source of omega-3”. Its alpha-linolenic acid (ALA) content is about 188–400 mg per 100 g fresh (wild genotypes roughly 188 mg/100 g; many sources cite 300–400 mg/100 g of fresh leaves), higher than spinach and with a favourable omega-3/omega-6 ratio. Besides ALA there are trace amounts of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA), along with linoleic acid (omega-6). Notably, purslane contains the catecholamines noradrenaline (norepinephrine), dopamine and DOPA at appreciable levels (Endress et al.; Chen et al., 2003; Xiang et al., 2005), a rare feature in an edible plant. Other groups include flavonoids (quercetin, kaempferol, apigenin, luteolin), the alkaloids oleracein and portulacanone, carotenoids (beta-carotene, provitamin A), vitamins C and E, glutathione and tocopherols, mucilaginous polysaccharides, organic acids (citric, malic, oxalic) and the minerals magnesium, potassium, calcium and iron.

Purslane is widely used as a vegetable: in Vietnam it is boiled, cooked in soup (canh rau sam), stir-fried, pickled or eaten raw in salads; worldwide there is Mexican verdolaga (stewed or in salads), Turkish yoğurtlu semizotu (with yoghurt), Japanese tempura and pickles. In traditional medicine it is considered cooling and sour, with heat-clearing, diuretic, anti-inflammatory and anti-dysenteric effects and use in digestive support; the crushed plant is sometimes applied to wounds and boils. Modern research: a review by Zhou et al. (2015, BioMed Research International) summarised the species' pharmacology; a Heliyon review (2022) and a 13-accession comparative study (2014) confirmed strong antioxidant activity; experiments in Wistar rats indicated neuroprotective effects (Martins et al.); and a randomised, double-blind clinical trial in 2024 in patients with non-alcoholic fatty liver disease (NAFLD) showed that purslane extract improved liver enzymes, blood lipids and inflammatory markers, attributed to ALA, flavonoids and antioxidants. Purslane is also used as livestock feed.

As food, purslane is considered safe and nutritious in ordinary culinary amounts. The main caution is its high oxalate content: a case of oxalate nephropathy linked to consuming large amounts of purslane has been reported (Wang et al., BMC Nephrology, 2023), so people with a history of kidney stones, kidney disease or hyperoxaluria should limit it; blanching or boiling and drinking enough water help reduce oxalate. Because it contains catecholamines, caution is advised with high concentrated doses alongside cardiovascular or blood-pressure medicines; pregnant women should use it as an ordinary vegetable and avoid high-dose extracts without advice. On conservation, the species is Not Evaluated (NE) on the IUCN Red List and is not listed in the CITES appendices; purslane is globally distributed, often weedy and extremely abundant and is not threatened — in some places it is even considered an invasive weed. Growing it and maintaining purslane landraces (including large-leaved, green-stemmed forms) helps conserve genetic diversity for food and medicine.