Purslane: Weeds, Food, and the Politics and Ethics of Nomenclature

THINKING ABOUT WEEDS, READING ABOUT WEEDS, DIGGING ABOUT WEEDS
Now that I've been gardening more, I've also been reading a ton online about plants and gardening.

Today I was reading more about weeds, which I've been thinking about a lot lately, as I become more familiar with the plants native to Michigan, the ones that are invasive, and the ones that are introduced but are not considered problematic.

WEED IDENTIFICATION RESOURCES: IMAGE GALLERIES, DATABASES
One thing I've been exploring a lot is the various weed databases that are around. Rutgers University has a really handy weed gallery with thumbnail photographs of the plants, helpful if you aren't as familiar with botany as some databases require the researcher to be. (The Illinois Council on Food and Agricultural Research weed identification tool, for example, though it is also very useful, asks you to specify the characteristics of a number of plant features to conclude what your weed is, which may overwhelm the neophyte gardener.) For Michigan, there's also a common weed seedlings gallery, which is, interestingly, much more comprehensive than the noxious and restricted weeds list for Michigan. (Ergonica will help you find your way to a similar list for your region, if you aren't local to MI.)

THINKING MORE IN-DEPTH ABOUT WEEDS
Today I came upon this fabulously interesting reading on weeds: course notes from a weed science course taught by Dr. Alan York at North Carolina State University. Although from an anthropological perspective, the idea of a plant "interfering with human activities" calls for some deconstruction and consideration, what's really great about the information he presents is that he deals in much more specific terms about the particular problems weeds pose to human populations than most sources I've come upon: "health hazards," "water management," "safety issues," etc. His detailed, quantified explanations of the reduced crop output of crops given particular levels of weed interference are particularly helpful for understanding the problem of weeds from his perspective.

THREATS TO BIODIVERSITY
Similarly, as someone generally concerned about the diversity of life on the planet, and with the conservation of (relatively) uncultivated land and its species, I'm chilled when I hear the Michigan State University's Invasive Species Initiative has to say about garlic mustard: "Garlic mustard is an exotic invasive plant from Europe that invades woodland habitats in North America and impacts forest biodiversity. In some woodlands, dense stands of garlic mustard in the spring threaten showy spring blooming ephemerals like spring beauty, trilliums and trout lilies. Other research points toward potentially negative impacts on timber species and forest health. Many land managers consider it to be one of the most potentially harmful and difficult to control invasive plants in the region." (See more on the Garlic Mustard Initiative, including photos, here.)

PURSLANE: THE PROBLEM OF CULTURE
But, to get back to what I mean about the deconstruction needed in thinking about weeds "interfering with human activities" (in Alan York's language), consider the example of purslane. (Thanks very much to Scrumptious, my dear friend who blogs about her CSA adventures in San Francisco, for pointing out this problem to me!) Purslane is called a "severe weed pest in vegetable crops and newly seeded turf" by the Rutgers University Agricultural Experiment Station. It gets a similar rap from most folks in the American mainstream. Yet, according to the organization Annadana, it was cultivated over 4000 years ago, and has been eaten for at least 1000 years by people in the Southwestern area of the United States. It's used by healers in the Andes, was used by Mayans in the Yucatan, and is grown as a vegetable in Africa. The Australian Naturopathic Network indicates it has been used also by Australian Aborigines, peoples in India and the Middle East.

As Rosemary Barron writes for the Weston A. Price Foundation for Wise Traditions in Food, Farming, and the Healing Arts, "the FDA lists purslane as a pervasive weed (the 7th worst, worldwide) but to those of us who love its earthy, slightly acidic flavor and crisp, succulent stems and leaves, the word ‘weed’ hardly seems fair." She explains further, "Medieval herbals describe purslane as ‘cold,’ meaning that it was considered a cure for a ‘burning’ (or malfunctioning) heart and liver. Greeks call it a ‘blood-cleansing’ herb. In Mexico, purslane is considered good for diabetics. Recent research has confirmed that purslane is one of the best vegetable sources of omega-3 fatty acids, as well as carotenes and vitamin C."

The CSA folks and naturopaths are clued into the human benefits of this plant. It's gotten the attention of medical researchers as well as the New York Times food and dining section. So why does the FDA still classify it as a weed? What exactly are the human activities with which it's interfering? Stretching green lawns in front of our domiciles that offer nothing to humans or beneficial animals in the way of foodstuffs?

Moreover, why does the American Heart Association not mention purslane anywhere in its omega-3 recommendations? Given the rising cost of food and devastating environmental problems leading to concerns about transportation of food, it should be much more widely publicized that the plant most Americans are trying to weed out of their lawns could actually help save their lives by reducing their risk of coronary heart disease, without paying a single penny to a pharmaceutical company.

Promoting the home cultivation and consumption of this omega-3-rich vegetable could also circumvent the problem that the recommendations for twice-a-week fish consumption, if it actually could be afforded financially by everyone in the population (a BIG if in a society -not to mention a world- with such great wealth disparities as ours has), would so much further contribute to overfishing that it would destroy the world's fisheries.

People. It's time to think about sustainability seriously, and not to treat it as something outside the purview of health sciences. We need to think seriously about how we live, if we want to continue to do it on this planet.


SOME RELEVANT HEALTH RESEARCH:
Ezekwe, Michael O., Thomas R. Omara-Alwala, Tadesse Membrahtu. "Nutritive characterization of purslane accessions as influenced by planting date." Plant Foods for Human Nutrition. Sept 1999 v53 i3 p183(9).

Guil-Guerrero, Jose L., and Ignacio Rodriguez-Garcia. "Lipids classes, fatty acids and carotenes of the leaves of six edible wild plants." European Food Research and Technology A 209.5 (Sept 1999): 313(4).

Purslane eyed as rich food source - US weed has beneficial nutrients
Agricultural Research, Dec, 1992, by Sean Adams

Simopoulos AP. "The omega-6/omega-3 fatty acid ratio, genetic variation, and cardiovascular disease" ASIA PACIFIC JOURNAL OF CLINICAL NUTRITION. 2008;17 Sup.1:131-134.
Simopoulos AP, Norman HA, Gillaspy JE, Duke JA. Common purslane: A source of omega-3 fatty acids and antioxidants. J Am College Nutr. 1992;11:374-382.

Simopoulos AP, Norman HA, Gillaspy JE. Purslane in human nutrition and its potential for world agriculture. World Rev Nutr Diet. 1995;77:47-74.

Simopoulos AP, Salem N Jr. Purslane: a terrestrial source of omega-3 fatty acids. N Engl J Med. 1986;315:833.

Simopoulos AP, Gopalan C (Eds). Plants in Human Health and Nutrition Policy. World Rev Nutr Diet, Basel: Karger, vol. 91, 2003.

Zeghichi S, Kallithrka S, Simopoulos AP, Kypriotakis Z. Nutritional composition of selected wild plants in the diet of Crete. World Rev Nutr Diet. 2003;91:22-40.

Simopoulos AP. Omega-3 fatty acids in wild plants, seeds and nuts. Asia Pac J Clin Nutr. 2002;11(S6):S163-S173.

Simopoulos AP. Omega-3 fatty acids and antioxidants in edible wild plants. Biol Res. 2004;37:263-277.