Wednesday Weed – Broad-leaved Everlasting Pea

Every Wednesday, I hope to find a new ‘weed’ to investigate. My only criterion will be that I will not have deliberately planted the subject of our inquiry. Who knows what we will find…..

Broad-leaved Everlasting Pea (Lathyrus latifolius)

Broad-leaved Everlasting Pea (Lathyrus latifolius)

Dear Readers, you may often see this sweet pea lookalike scrambling amongst the buddleia between railway lines, or erupting from wasteland beside electricity substations. Here in East Finchley, it is often seen  in more weed-friendly front gardens, and if it cropped up in mine I would certainly leave it, pretty plant that it is. Unlike the ‘domestic’ sweet pea, this plant has no scent and is a perennial with a preference for clay soil, largely because although it likes full sun, it requires moisture, which heavier substrates provide. Although in its wild form it is sometimes considered to be a weed, there are also cultivated varieties which are marketed as ‘everlasting sweet pea’. It seems that the dividing line between ‘pest’ and ‘garden plant’ is even more blurred with this plant than with other species.

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The ‘peas’ of other members of the Lathyrus genus cause a kind of poisoning called Lathyrism, which causes paralysis of the larynx, excitability, paralysis of the lower limbs and eventual death. Lathyrus sativus, or the grass pea, has been a famine food in several countries, and during the Spanish War of Independence against Napoleon resulted in the deaths of many poor people, as documented by Goya in the woodcut below. The cultivated sweet pea causes a slightly different kind of poisoning, which attacks the connective tissue. Although there is no evidence to suggest that broad-leaved everlasting pea has been implicated in any such nastiness, I’d certainly be very reluctant to ingest any parts of this plant, although I have seen the flowers described as edible.

'Because of the grass pea' - this aquatint by Goya shows a woman already crippled by the effects of eating grass pea porridge as a famine food.

‘Because of the grass pea’ – this aquatint by Goya shows a woman already crippled by the effects of eating grass pea porridge as a famine food.

Broad-leaved everlasting pea first appeared in cultivation in the UK by the fifteenth century, and had ‘escaped’ by 1670. I am curious as to why it was originally ‘imported’ – many early plants were brought here because of their medicinal properties, or their value as food plants or flavourings, but this plant has none of these benefits, at least as far as I’m able to ascertain. I wonder if its combination of tolerance of clay soils and nitrogen fixing abilities made it a good choice as a ‘green manure’ for improving soils? On the other hand, maybe it was brought here solely by virtue of its hardiness and attractiveness. It certainly attracted the attention of such artists as P.J.Redouté, who is  perhaps better known for his nineteenth century paintings of old-fashioned roses.

Swallowtail Garden Seeds (https://www.flickr.com/photos/swallowtailgardenseeds/14913883105)

Lathyrus latifolius by P.J. Redoute (1833) (Photo One – see credit below)

So, next time you are sitting on a crowded train heading out of London Bridge or Waterloo stations, have a look at the mass of ‘weeds’ growing at the junctions between the lines. I can more or less guarantee that somewhere there will be a neon-pink tangle of broad-leaved everlasting pea brightening up the place. It’s amazing what you can spot during a commute. It’s almost worth bringing your binoculars.

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Photo Credits

Photo One – Swallowtail Garden Seeds (https://www.flickr.com/photos/swallowtailgardenseeds/14913883105)

All other photos copyright Vivienne Palmer. Free to use and share non-commercially, but please attribute and link back to the blog, thank you!

4 thoughts on “Wednesday Weed – Broad-leaved Everlasting Pea

    1. Bug Woman Post author

      Hi Ann, well Lathyrism is specifically associated with plants in the Lathyrus genus, particularly Lathyrus sativus, and is caused by a chemical called Oxalyldiaminopropionic acid (ODAP). Laburnum is also in the pea family, as you know, but the chemical here is cytisine, which apparently is very similar to nicotine and can be used for smoking cessation (when it isn’t poisoning people 🙂 ). Interesting how a group of plants which provide so much benefit for humans also contain such a variety of toxins. I’m making the rash assumption that they were developed by the plants in an arms race against being eaten by animals, but it’s probably more complicated than that….

      Reply

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