Portuguese laurel

Discussion in 'Woody Plants' started by marisol, Sep 26, 2009.

  1. marisol

    marisol Member

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    Can someone please tell me if Portuguese laurel leaves can be used for seasoning food? I guess I am wondering if this is what we know as bay leaves . . .
     
  2. Silver surfer

    Silver surfer Contributor 10 Years

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  3. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    Shows the value and importance of avoiding misleading English names!
     
  4. JenRi

    JenRi Active Member

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    Indeed!
     
  5. Dana09

    Dana09 Active Member

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    When I googled Portuguese Laurel for some reason, I came up with some info that it develops arsenic in the wood and ought not to be burned,
    so,
    I don't think I would be inclined to use it as a food enhancer myself!
    The birds seem to do alright with the berries tho don't they?
     
  6. bjo

    bjo Active Member 10 Years

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    Hi,

    I know that Michael and myself will never agree about common names, but this time I'll go a little way with him.....

    to quote Michael

    "Shows the value and importance of avoiding misleading English names! "

    To me, the key word here is English. Neither species is native to English speaking countries and therefore have no "natural" name in English. Hillier's Manual gives a date for introduction to UK for Laurus nobilis of circa 1562 and for Prunus lusitanica, 1648. So presumably, the English names date from about this time.

    Here in Portugal where both species are native, there is no confusion in the common names:

    Laurus nobilis = Loureiro
    Prunus lusitanica = Azereiro or Ginjeira-brava

    I certainly would not recommend using Prunus lusitanica leaves as a substitute for bay leaves, but is there any real evidence that they are poisonous ? (perhaps there is confusion with Prunus laurocerasus?)...and I am dubious (but prepared to be convinced) that there would be enough arsenic in the wood to cause problems.....however, I am not offering to try either experiment !!

    Brian
     
  7. Michael F

    Michael F Paragon of Plants Forums Moderator 10 Years

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    The arsenic idea sounds highly improbable to me. But all Prunus species (not just P. laurocerasus) contain cyanogenic glycosides in their foliage; if the leaf is damaged by a browsing animal, these react to produce cyanide, to discourage and/or poison the browsing animal.
     
  8. Silver surfer

    Silver surfer Contributor 10 Years

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    This is all very interesting. However, I just hope that marisol who originally posted the question, has been back to see the answer!
     
  9. Dana09

    Dana09 Active Member

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    And more notes of interest.
    Yes, it is cyanide, not the other lethal toxin.

    "Found naturally in the stones of cherries, plums and peaches, the cores of apples and the leaves of the laurel plant, cyanide evolved as a plant protection mechanism of grazing animals (interestingly, a number of bacteria, fungi and algae are also found to produce the chemical). Ingestion of moderate amounts of these natural substances cause headaches accompanied by mild heart palpitations, more than enough to steer animals – two-legged or four – clear. However, the Middle Eastern people of ancient times made the discovery that the distillation by evaporation of laurel leaves produced lethal concentrations of this innocent plant product.

    Although cyanide has found usage in the gold industry2 and butterfly collection (collectors used hydrocyanic acid – produced by the fermentation of crushed laurel leaves – in their collection bottles), its most notable use throughout history was as a poison. One of the first administrators of cyanide was said to be Livia3, the wife of Augustus who, in AD 14 killed her husband by soaking his figs in the poison. A number of people elected to end their lives by cyanide: Adolf Hitler, Eva Braun, Hermann Goering, and Alan Turing. The poison was stockpiled by both the United States and the Soviet Union during the 1950s and 1960s – indeed, it was thought that the Soviet Union had plans to use them to clear their way right into enemy territory."

    and
    "Whilst we are talking of Laurels, it is interesting to note that there are other dangers with some Laurels. For instance, the Portuguese Laurel (Prunus lusitanica) has cyanide compounds in its leaf structure. On no account should this foliage be burnt."

    Interesting to live so long with these trees and never know this fact til now.

    D
     
  10. bjo

    bjo Active Member 10 Years

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    Hi,

    Michael is right about leaves of Prunus species containing cyanogenic (cyanide producing) compounds. However, as with so many things, what is critical is not the presence of a compound but the quantity. As I had this suspicion that Prunus lusitanica was not especially poisonous, I did a little web browsing.....

    First thing I came across was the suggestion that probably all higher plants produce cyanide as part of their normal metabolism.

    Second, perhaps 12,000 species across more than 100 families produce significant amounts and would be considered "cyanogenic". These plants include many important food crops - notably cassava which can be very dangerous unless properly prepared. Linseed - a health food - has a cyanide production potential of 11 to 33 mg per 100g!

    Almonds (Prunus dulcis) owe much of their flavour to the cyanide content. Bitter almonds contain up to 300mg cyanide potential per 100g. Sweet almonds up to 5mg/100g.

    Then by luck I came across an article that deals directly with our two species (Santamour, FS (1998) "Amygdalin in Prunus leaves" Phytochemistry 47(8) 1537-1538). Next bit of luck, although there is not free access to the article, I managed to get a copy.

    It confirms my suspicion (recalculating the data) in one analysis (the concentrations do vary), leaves of Prunus laurocerasus contained 310 mg cyanide potential/ 100g, but Prunus lusitanica only 10.9 mg/100g.

    Logically there should be a difference in the resistance to herbivory between the two species - perhaps they are targetted by different types of grazer?

    I enjoyed my bit of browsing on the web(especially as it confirmed my supicions !!), but I am still not going to browse on Portugues laurel leaves anytime soon!

    Real conclusion, as Silver Surfer says, stick to Bay (Laurus nobilis)

    Ciao
    Brian
     

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