Tuesday, July 27, 2010

Shepherd's purse

Binomial name: Capsella bursa-pastoris
Common name : Shepherd's purse

Identification:

It occurs in autumn and winter on our property (SE Queensland). The basal rosette is like dandelion and sowthistle, but the leaves are quite narrow with some shallow regular serrations and with sparse, in number, very fine hairs along the edge of the leaf. There is a core string like dandelion
and catsears if you try and pull a leaf
apart. The seed spikes are quite distinctive with seed pods that look like small hearts.


History:

Originally from Eurasia but now cosmopolitan. Probably it has been used by humans for a long period - seeds were found in an archaeological site in Turkey dating from 5800B.C. In ancient Greece it was used as a laxative and in the middle ages as a haemostatic agent (to stop bleeding). In a certain part of China it is used as a substitute for bok choy in wontons. It is sold in Asia as a vegetable and a larger variety has been developed.

Nutritional:

(per 100gm leaves)
omega 3 fatty acids 233 mg
RAE (retinal A equivalent) 433mg
B carotene 5,200IU Vit C 104mg (an orange is about 80mg) + some minerals.
These levels are very similar to Spinach (Spinacea oleracea) , apart from the omega 3 fatty acids which is 138mg for spinach.

ref : Kallas,J Edible Wild Plants - Wild foods from Dirt to Plate Gibbs Smith 2010

What parts to eat:

young leaves in a salad, older leaves as a potherb ( reduces alot when boiled) taste is reported as peppery - it is really only mildly so, in the plants we have growing.

Medical: (Pubmed - search term Shepherd's purse)

Not much to report - undoubtedly though it has excellent anti-oxidant activity by virtue of the RAE and carotenoid content. There was a report of several pigs dying from nitrite poisoning from eating weeds with Shepherd's purse implicated ( abstract 60). Not medically related, but interesting, was a use of Shepherd's Purse for bioremediation of contaminated soil (it worked well). Another abstract indicated that it inhibited melanocyte activity and thus may have a skin whitening effect (abstract 26).

Conclusion:

Another quite nutritious edible weed, however there are lots of questions - if it stops bleeding externally what effect does it really have internally. I would like to see some proper trials on this, especially with regard to blood pressure if it does indeed cause vasoconstriction. John Kallis, in his book, indicated that a serve of this weed gave him a slight headache for 5 hours - I would be concerned that this was related to an increase in blood pressure.
So - just eat a few leaves mixed in with other greens would be my advice until there is some decent evidence available.


Tom

Photos once again from google images - still haven't had digital camera fixed- I need to see one of our tech savvy daughters to see if it is simply a setting that needs adjusting!

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