Portulaca oleracea Seeds | Purslane
LATIN NAME: Portulaca oleracea
COMMON NAME: Purslane
Plant Profile
Look at a purslane plant that has finished flowering and you may find two different sets of seed. Small, glossy black seeds are shed from capsules that open normally, and they are hard-coated and slow to start, staying dormant in the soil for years. Larger, brown seeds come from flowers that never open at all, and they start quickly and grow at once. The two together are an insurance policy: some of the offspring wait for another season, and some exploit the current one. For a gardener this explains why purslane seems to vanish and reappear on its own schedule.
The seed capsule opens by lifting a single circular lid, like the top of a small pot, and the seeds inside are minute and sculpted with stellate, star-like ridges that are distinctive under a hand lens. Stems are smooth, reddish and watery, breaking with a snap; leaves are alternate or almost opposite on the lower stem, thick to the point of looking inflated, and the flowers are small and yellow, opening in the morning sun for a few bright hours and shutting by early afternoon. There are five petals and many stamens, and the whole display lasts a single morning per flower.
Among leafy greens purslane is the outstanding source of alpha-linolenic acid, the plant omega-3. The leaf also supplies vitamin E, vitamin C, beta-carotene, magnesium and potassium, and the seeds contain a good share of the same oil. From a biotech angle the species has been used as a source of polysaccharides for cosmetic formulation, and as a tissue-culture subject for the production of the leaf’s antioxidants; it has also been studied for its capacity to accumulate metals, which is useful for cleaning contaminated soil and a caution for anyone harvesting from a roadside verge.
Science & Biotechnology
Most leafy vegetables use one photosynthetic pathway and stick to it. Purslane runs a C4 system, concentrating carbon dioxide before fixing it, which is well suited to hot, bright conditions. Under a real drought it also begins to take up carbon dioxide at night in the manner of CAM plants, storing the acid until daylight and closing its pores in the heat. That flexibility explains its performance in a dry summer, and it has made the species a model for studying how the two pathways interact inside a single leaf.
Uses & Benefits
An unusual feature of purslane is its content of catecholamines. Leaves and stems carry dopamine, noradrenaline and related compounds, together with the mucilage that gives the raw leaf its slightly slimy, soothing texture when chewed. The mucilage is a water-soluble polysaccharide, and it is the reason the bruised leaf feels cool on a sting and why the plant has a long record as a poultice for burns and insect bites. The whole plant also holds oxalic acid, which is worth knowing if you are cooking for anyone prone to kidney stones; blanching and discarding the cooking water reduces it.
The crop yields by the handful if handled properly. Pinch the soft tips of the running stems, three or four leaves back from the growing point, and the plant branches and pushes more shoots. Repeated pinching over a warm season is far more productive than a single pull, and pinching before the flowers open keeps the leaves tender rather than leathery. The washed leaves go raw into salads with yoghurt and garlic, into soups in the last minute of cooking, or into pickles, where their crispness survives.
Growing from Seed
Purslane seed is very small, so prepare a fine tilth rather than a lumpy bed and sow it on the surface, pressing it in lightly, because the seed wants light to sprout. Thin the rows to about fifteen centimetres, water gently until the soil is damp but never wet, and avoid sowing into cold ground: warmth is the signal it waits for. Once the plants have knitted together they shade out most competition and need almost no attention. Over-watering produces rank growth and rot at the base, so let the surface dry between waterings.
Leaf form and stem habit together settle identification better than any single character.
Our Take
If you have ever weeded this plant off a path, grow a row deliberately and you will appreciate it properly. It is the easiest hot-weather salad crop I know, and it will feed you through a drought that has flattened the lettuce. For comparison, Portulaca quadrifida is the small-leaved tropical relative that does the same job in humid heat, while Basella rubra gives you a climbing leafy crop through the wettest part of the year. Where the ground is cooler and you would rather have an upright leaf, Bloomsdale spinach remains the standard against which all of them are judged.
Related Reading
Gardeners who grow Purslane often pair it with these related subjects: