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linaria_z7_ch

help with Persicaria-like weed

linaria_gw
9 years ago

Hi there,
I found this rather nasty weed when touring some perennial plantings. Pics taken in October,
the plant grows long rhizomes, seedhead looks Polygonum-Persicaria-ish, can`t think of a species with those wiry rhizomes though.

Location: midnorthern Europe, avarage soil

Thanks for your help, bye, Lin

Comments (6)

  • linaria_gw
    Original Author
    9 years ago

    here another pic,

    it grew somewhat taller than 1 foot, working its way through a dense cushion of Aster dumsosus

  • linaria_gw
    Original Author
    9 years ago

    and another stalk from that plant,

    hope that helps,

    Lin

  • missingtheobvious
    9 years ago

    Persicaria amphibia might be a possibility, if the location is not too dry. (Wiley mentions "wetland (or fomer wetland)" in Britain.)

    Photos here:
    http://www.irishwildflowers.ie/pages/614a.html

    Location maps here:
    http://onlinelibrary.wiley.com/doi/10.1046/j.1365-2745.2001.00571.x/full

  • floral_uk z.8/9 SW UK
    9 years ago

    Periscaria amphibia has different leaves and needs a very, very wet habitat. the leaves usually float on the surface of ponds.

  • linaria_gw
    Original Author
    9 years ago

    Hello missingtheobvious,
    thanks for those links, I skimmed them and was impressed by their detailed information,
    a nice bookmark for future refenrence.

    And I think you got that one rigt, I just hadn`t met the P. amphibium in person and was distracted by those rhizomes.

    And flora, I think it got dumped there with the soil and even though it does not thrive, it holds its ground and spreads, the soil is heavy and moist, other perennials I am familiar with look well fed, and there is a wandering shade from a nearby building keeping off the midday sun.

    And I managed to get hold of a serious botanical book, some identification key,
    there the only Polygonum (it is an old book) with rhizomes is P. amphibium, a very neat drawing showing a terrestial form and an aquatic form! Flowers, foliage, hairy surface all fit,
    so I am to 98% positive.

    Thanks for your help,

    bye, Lin

  • floral_uk z.8/9 SW UK
    9 years ago

    Interesting - I've only ever seen it floating on ponds.