Purslane/Pigweed (Portulaca oleracea & spp.)
Devotee of sidewalk cracks the world over. © JPM, 2022.
Names
Another of the world's ancient weeds, this fleshy, drought-adaptable summer plant hails from the genus Portulaca (P.) and goes by a few English names: purslane and pigweed are the two most common; it is also called moss rose, especially in the USA, although citizens of that country should be aware that the unrelated fat hen or goosefoot (Chenopodium album) is also called pigweed there. Some of the older colonial literature such as the diaries of the failed Bourke & Wills expedition and colonial botanist Ferdinand von Mueller may also refer to this plant as portulac. The First Nations people across the world have as many traditional names for it as there are tribes.
There are more than 20 native and introduced species in Australia, the most common being common purslane, P. oleracea. Other Australian species of note include slender pigweed (P. filifolia), a thin-leaved arid clime variant; buttercup pigweed (P. intraterranea), a large-flowered and very important desert bush food plant; and heart-plant (P. bicolor), noted for its yellow or pink flowers, although it is probably too small to bother harvesting. One popular ornamental purslane is the large-flowered P. grandiflora, which is typically too bitter to eat, as is P. pilosa, noted for its pink flowers and burning, bitter foliage (Deane, 2011, comments below article). A seaside species is also a known edible (Sesuvium portulacastrum), but this will be covered in detail in another foraging article.
Habitat and Range
Purslane is a reasonably common plant and another first occupier of desolate, disturbed or difficult ground. Its fleshy stems, leaves and taproots are adept at storing water, enabling this intrepid adventurer to survive to reproduction in otherwise inhospitable environs such as pavement cracks, roadsides, rocky ground, and deserts. It is common in trampled places such as footpaths, trails, driveways, agricultural roads and orchard rows, and will spring up everywhere, especially your garden, after substantial rain. Colonial explorers relished themselves on this plant during their barren journeys into Australia's dry interior, where purslane may still be found in abundance. Purslane prefers warmer weather, being more prolific in the northern and arid regions of the continent. It does occur abundantly in southern parts of Australia particularly between spring and autumn (September-April), and being far less common in Tasmania and southern Western Australia. As a plant with global distribution, purslane may be found on every continent save Antarctica.
Figure 1. Distribution of Portulaca (all species) across the continent. Atlas of Living Australia.
Identification
Key Identifying Features
- Thick, greenish-red, fleshy stems growing from a central taproot, usually ground-hugging but may prop up to 15-25 cm in height
- Stems are smooth with a clear sap (very important!)
- Leaves emerge from the stem joints or at the stem tips
- Leaves are 1-3 cm, smooth and stubby with rounded tips and fleshy in texture (some species leaves may be heart-shaped or thin)
- Flowers are yellow (some species of Portulaca may be dark or light pink) with five petals, appearing at stem joints or stem tips.
- Flowers set into small, green, lidded capsules
- Capsule lids pop off when ripe, revealing dozens of tiny black seeds
- Some species (e.g. P. filifolia and P. tuberosa) may have a substantial tap root.
Figure 2. Common purslane (P. oleracea, centre) is instantly recognisable by its fleshy stems and sprawling habit. Sydney Olympic Park. © JPM, 2022.
Figure 3. A close-up of the smooth, reddish, branching stems of P. oleracea. Leaf positions at the stem joints or stem tips is also obvious. Sydney Olympic Park. © JPM, 2022.
Figure 4. Foliage of common purslane (P. oleracea) is rounded and stubby. Sydney Olympic Park. © JPM, 2022.
Figure 5. Foliage of the slender pigweed (P. filifolia) tapers to a stubby tip. Atlas of Living Australia. © M. Fagg, 2020.
Figure 6. Buttercup pigweed (P. intraterranea) has a foliage profile very similar to P. oleracea, excepting its larger flowers. Atlas of Living Australia. © R.W. Purdie, 2016.
Figure 7. Heart-plant (P. bicolor) is aptly named! Atlas of Living Australia. © K. Nicolson, 2021.
Flowers are small and short-lived, lasting less than a few days at most. The common purslane (P. oleracea), slender pigweed (P. filifolia) and buttercup pigweed (P. intraterranea) all have yellow flowers; some other species such as heart plant (P. bicolor) may also have pink or whitish-pink flowers. Flowers have five petals (occasionally, four or six), but this feature can be difficult to discern on common purslane (P. oleracea); other species have very conspicuous flowers (see figures 5-7 above). Flowers will self-pollinate and quickly turn into tiny, green capsules shaped like urns, including a tapered lid! Ripe capsules will turn slightly yellow at the base and their lids will pop off, emptying their dozens of minuscule black seeds for dispersal by wind.
Figure 8. The small, yellow flowers of common purslane (P. oleracea) appear in the leaf joints. Sydney Olympic Park. © JPM, 2022.
Figure 9. Close-up of a common pigweed (P. oleracea) flower. The number of petals on this species is difficult to discern. Sydney Olympic Park. © JPM, 2022.
Figure 10. After pollination, the flowers turn into small, tapered capsules (P. oleracea, pictured). One of the capsules has no lid, showing the black seeds inside. Sydney Olympic Park. © JPM, 2022.
Figure 11. Close-up of the tiny, edible seeds and an open pod of common purslane (P. oleracea). Sydney Olympic Park. © JPM, 2022.
Culinary Uses
Purslane is one of those ancient vegetables with thousands of years of recorded human use on every continent. All sources report that purslane is extremely high in Vitamin E (Chevallier, 1996; Duke, 2002; Apelian, 2021) and purslane greens are oddly high in omega 3 fatty acids, although Duke (2002: 156) notes that walnut or mustard (Brassicaceae) oils have more omega 3s. Modern nutritional testing shows just how good it is (Williams, 2012: 320):
All parts of the plant are edible, although most of the use tends to be the above-ground parts: leaves, stems and seeds. Not all species are equally delectable, however, so it is worth trying a plant before committing to harvest. Leafy shoots of young plants, prior to flowering, can be eaten raw in salads, but this should be sparing due to this plant's oxalic acid content. Chopped raw leaves go well with yoghurt, e.g. in tsatsiki or raiti; in fact the calcium and perhaps microbiota in dairy goes a long way to alleviating adverse effects of the oxalates in the raw plant. Older plants (that is, flowering or post-flowering) are much better cooked like spinach, blanched a few minutes and rinsed in cold water, after which it can be liberally added to stir fries, soups and stews, chopped up for sandwiches etc. The juicy, thick stems of adult plants make ideal pickles: brine, vinegar, or salt & white wine (Duke, 2002).
Figure 12. Purslane is best boiled before consumption to remove oxalic acid. © JPM, 2022.
Figure 13. A fatty-acid feast! Lamb cutlets, eggs and butter-fried purslane! © JPM, 2022.
Purslane seeds are incredibly nutritious, packing 19.8 g of protein, 10.4 g of fat and 55.4 g carbohydrates per 100 grams (Low, 1989: 220-221). Their minuscule size makes them somewhat tedious to harvest, however. Australian First Nations tribes, particularly those of the central desert after rains, would heap up massive piles of this plant onto kangaroo skins or spinifex mats (a tarp would work just as well nowadays) and leave them to dry. The piles would then be beaten and the tiny seeds would fall out of their pods and were collected in large amounts and subsequently ground with stones and eaten or baked into cakes (Low, 1989: 87). Each plant can bear upwards of 10,000 seeds, making harvest of this plant an important desert food staple even today.
The desert species, buttercup purslane (P. intraterranea), also has quite a substantial taproot, as can slender pigweed (P. filifolia), both of which are worth roasting and taste somewhat like potato (Low, 1988: 156). Common purslane taproots are not as substantial but still contain valuable carbohydrates and minerals and can likewise be eaten.
Figure 14. Taproots of common purslane (P. oleracea) can be eaten but are not as substantial as the desert species. Sydney Olympic Park. © JPM, 2022.
Figure 15. If you live in the desert, slender pigweed often has a taproot worth roasting. Atlas of Living Australia. © M. Fagg, 2020.
Some sources mention that purslane plants can be dried and burnt into a fine ash which makes a reasonable, albeit alkaline, salt substitute (Apelian 2021: 103). This salt is likely high in potassium rather than sodium (see Williams' nutritional analysis above).
Medicinal Uses
It should be of no surprise that this versatile plant has many applications in herbal medicine. Ivan Ross (2003: 407-410) lists more than 30 clinically proven pharmacological activities for common purslane (P. oleracea); Duke (2002: 599) lists 28, including antibacterial, antioxidant, analgesic (painkilling), antitumour, antiulcer, and molluscicidal. Most of the herbal preparations were methanol or ethanol (95%) extracts; some of the antibacterial preparations used acetone extracts; others utilised hot water extracts (see Ross, 2003, and the references cited there for details). A full review of purslane (P. oleracea) phytochemistry and its pharmacological effects is available in Zhang et al. (2015).
More specific applications include those detailed by Apelian & Davis (2020: 126), including as an effective treatment for bronchial (breathing) issues like asthma by eating the vegetable or taking a methanol extract. They also supply a recipe for a purslane (P. oleracea) and mullein (Verbascum thapsus) anti-asthma medicine (1 dropper = single discharge of a rubber dropper); drink in parts throughout the day or completely as needed to alleviate coughing and improve pulmonary circulation and oxygen absorption in the lungs:
- 3 droppers purslane tincture
- 1 1/2 droppers of mullein tincture
- 1/4 cup water.
Chevallier (1996: 253) remarks that purslane juice or a decoction is useful for skin ailments like boils and carbuncles, in addition to its aforementioned antibiotic/antifungal effects useful for treating hookworm; purslane juice is diuretic (causes urination, like coffee does); and mucilaginous (gel-jelly) properties in the digested vegetable to help sooth gastrointestinal upset, diarrhea and dysentery.
Duke (2001: 156-157) mentions that American First Nations tribes had varied medicinal uses for the plant: Cherokee herbalists used the juice for earache and parasites; the Iriquois made a poultice for burns and bruises; and the Navajo deployed its mucilage to alleviate stomachache.
Look-alikes
Spotted spurge (Euphorbia maculata) is the most probable misidentification for the novice purslane-hunter (Apelian, 2021: 304). It has a similar, ground-sprawling habit and reddish stems, although its leaves grow oppositely the length of its stems, unlike purslane which has leaves only at stem joints or stem tips. Secondly, spotted spurge sometimes has a dark spot in the centre of the leaf, hence the name. Thirdly, all spurges will drip an acrid, white latex as their primary defense; this milky sap is very potent and excellent at dissolving proteins such as human skin (yes, it can be used to dissolve warts, corns, skin cancers, moles, etc, but with great care!). Purslane has clear or no obvious sap when its stems are damaged. Fourthly, spotted spurge has tiny white flowers that turn into hairy capsules; purslane capsules are smooth and flowers are never white (some purslane species may have faint pink flowers). Lastly, spotted spurge has fine, glassy hairs on the stems and the leaves, especially leaf undersides; purslane is glabrous = hairless!
Figure 16. Spotted spurge (Euphorbia maculata) is a common weed which could be easily confused with purslane (P. oleracea). Spotted spurge always drips white, milky sap, a key identifying distinction. Atlas of Living Australia. © G. Taseki, 2021.
Figure 17. Close-up of spotted spurge stems, showing the miniscule, clear hairs (also on the leaves); purslane is hairless. Notice the leaves grow opposite each other the whole stem length, also unlike purslane. Atlas of Living Australia.© T. Mesaglio, 2021.
Caution!
Raw purslane is high in oxalic acid, far more than spinach, a plant toxin that can result in various mineral deficiencies and kidney stones. It is soluble in water and nullified partially by high-calcium or high-magnesium foods such as dairy and nuts. Consume raw purslane in moderation and consider boiling or pickling this plant if you intend more regular consumption.
Further Reading
Apelian & Davis (2020), Herbal Remedies, pp. 125-126.
Apelian (2021), Forager's Guide, p. 103.
Atlas of Living Australia, "Portulaca oleracea." [LINK]
Atlas of Living Australia, "Portulaca bicolor." [LINK]
Atlas of Living Australia, "Portulaca filifolia." [LINK]
Atlas of Living Australia, "Portulaca interterranea." [LINK]
Atlas of Living Australia, "Portulaca grandiflora." [LINK]
Chevallier (1996), Medicinal Plants, p. 253.
Bonetto (2021), "Purslane, the Summer Edible Weed that Gives So Much." [LINK]
Deane (2011), "Purslane: Omega 3 Fatty Weed." [LINK]
Duke (2001), Edible Weeds, pp. 156-157.
Duke (2002), Medicinal Herbs, pp. 599-600.
Grubb & Raser-Rowland, Weed Forager's Handbook, pp. 96-100.
Low, Tim (1988), Wild Food Plants of Australia (Sydney: Angus & Robertson), p. 156.
Low (1989), Bush Tucker: Australia's Wild Food Harvest (Sydney: Angus & Robertson), pp. 86-87, 138-139, 151, 220-221.
Low (1991), Wild Herbs, p. 90.
Ross, I. A. (2003), Medicinal Plants of the World, Vol. I (Totowa: Humana Press), pp. 405-414.
Williams, Cheryl (2012-13), Medicinal Plants in Australia, Vol. III, pp. 319-320 & Vol. IV, pp. 118-123.
Zhang et al. (2015), "Portulaca oleracea L.: A Review of Phytochemistry and Pharmacological Effects." BioMed Research International 2015: 925631 [LINK]
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