Hi Dr. Cordain,
You might be interested in this weed. I have been pulling it out of my gardens for years and tossing it aside. Not anymore. I hope all is well.
Although purslane is considered a weed in the United States, it may be eaten as a leaf vegetable. It has a slightly sour and salty taste and is eaten throughout much of Europe, the middle east, Asia, and Mexico. The stems, leaves and flower buds are all edible. Purslane may be used fresh as a salad, stir-fried, or cooked as spinach is, and because of its mucilaginous quality it also is suitable for soups and stews. Australian Aborigines use the seeds to make seedcakes. Greeks, who call it andrakla (αντράκλα) or glystrida (γλυστρίδα), fry the leaves and the stems with feta cheese, tomato, onion, garlic, oregano, and olive oil, add it in salads, boil it or add to casseroled chicken. In Turkey, besides being used in salads and in baked pastries, it is cooked as a vegetable similar to spinach. In the south of Portugal (Alentejo), “baldroegas” are used as a soup ingredient. Because of its high water content Purslane cooks down quite a bit. Pick more than you think you will need. Makes a quick cold soup in hot weather by cooking and blending together with other vegetables.
Purslane contains more omega-3 fatty acids (alpha-linolenic acid in particular) than any other leafy vegetable plant. Research published by Artemis P. Simopoulos states that Purslane has 0.01 mg/g of eicosapentaenoic acid (EPA). This is an extraordinary amount of EPA for a land-based vegetable source. EPA is an Omega-3 fatty acid found mostly in fish, some algae, and flax seeds. It also contains vitamins (mainly vitamin A, vitamin C, and some vitamin B and carotenoids), as well as dietary minerals, such as magnesium, calcium, potassium, and iron. Also present are two types of betalain alkaloid pigments, the reddish betacyanins (visible in the coloration of the stems) and the yellow betaxanthins (noticeable in the flowers and in the slight yellowish cast of the leaves). Both of these pigment types are potent antioxidants and have been found to have antimutagenic properties in laboratory studies.
100 Grams of fresh purslane leaves (about 1 cup) contain 300 to 400 mg of alpha-linolenic acid. One cup of cooked leaves contains 90 mg of calcium, 561 mg of potassium, and more than 2,000 IUs of vitamin A. A half-cup of purslane leaves contains as much as 910 mg of oxalate, a compound implicated in the formation of kidney stones, however, note that many common vegetables, such as spinach, also can contain high concentrations of oxalates.
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 ten times the malic acid content as when harvested in the late afternoon, and thus have a significantly more tangy taste.