Feb 07 2011

Quiz: What plant is this?

Published by at 7:15 am under Quiz

I can usually identify this plant in a heartbeat, but I was stumped when I saw this photograph.  Maybe you will be too, so I've made it a quiz. 

Here are some clues:

  • The plant is a perennial native of Asia.
  • It's invasive in North America wherever it's found.
  • The stems are hollow and stand over 10 feet tall, persisting through the winter.
  • The plant spreads by wind-borne seeds and rhizomes. 
  • The rhizomes are particularly difficult to eradicate and result in dense stands of this plant.
  • It was originally brought here as an ornamental because it's flowers are arranged in pretty cream-colored sprays above the stems.  (This is the flower stalk in winter.)
  • The young stems are edible and taste like rhubarb but Americans don't like it well enough it to reduce its population by harvesting.

Do you know what it is?  Leave a comment with your answer.

(photo by Dianne Machesney)

23 responses so far

23 Responses to “Quiz: What plant is this?”

  1. Anne Marieon 07 Feb 2011 at 7:36 am


  2. Bill Parkeron 07 Feb 2011 at 7:56 am

    Is it Japanese Knotweed (Fallopia japonica, syn. Polygonum cuspidatum, Reynoutria japonica)?

  3. Mary Ann Pikeon 07 Feb 2011 at 8:20 am

    Given the shape of the flower head, I’m guessing Japanese Knotweed.

  4. paul wiegmanon 07 Feb 2011 at 8:25 am

    The dreaded Japanese knotweed. The dead twisted seed heads line the Yough between Confluence and Ohiopyle.

  5. Larisaon 07 Feb 2011 at 8:32 am

    Hi Kate!

    Sound like Knotweed. There used to be a festival in spring around it, but I’m not sure if that has continued.

  6. Carlaon 07 Feb 2011 at 9:20 am


  7. Marcy Con 07 Feb 2011 at 9:24 am

    I am thinking Japanese Knotweed….I think so far I have kept it from the yard, but not easy to do, it’s at the end of our road….this takes over creek and river banks….not a good way to control unless you keep ahead, you get the plant before the roots literally take hold…even putting heavy dark tarps and plastic doesn’t kill it…very, very agressive!!!

  8. Stephenon 07 Feb 2011 at 10:12 am

    Does this plant have thorns, and are the stems red?

    I have no idea what this plant is, but I’m thinking I’ve seen this all over the fields.

  9. Donnaon 07 Feb 2011 at 11:01 am

    Is it a wild grape vine?

  10. Peteron 07 Feb 2011 at 11:03 am

    I’m guessing it must be Japanese Knotweed, but that took some detective work on my part. Definitely don’t get any credit if this wasn’t an “open-book quiz.”

    Looking at the pictures of it in summer, it does seem familiar. I’ll have to keep my eyes open as summer comes around.

  11. Gigion 07 Feb 2011 at 11:26 am

    Perhaps Japanese knotweed?

  12. TJon 07 Feb 2011 at 11:34 am

    Is it bamboo?

  13. steve Son 07 Feb 2011 at 11:45 am

    i believe it is a member of the Polygonaceae family, ‘Polygonum cuspidatum’, commonly known as Japanese Knotweed.

  14. kellyon 07 Feb 2011 at 12:10 pm

    i’m going to guess….japanese knotwood with some sort of gall or other parasite.

  15. Markon 07 Feb 2011 at 12:12 pm

    Too early for responses? How about Japanese knotweed?

  16. Steve Colemanon 07 Feb 2011 at 12:36 pm

    Hi Kate,
    Japanese Knotweed.

    Just checking on Perigrine falcons if back in town and where they may have gone this winter?

    Great blog. I should look here more often.

    Best Regards,

  17. Kate St. Johnon 07 Feb 2011 at 12:47 pm

    Great responses, everyone! Yes, it’s the dreaded Japanese knotweed.

    I’m used to the look of the plant as a whole but not this small piece of it. I found some yesterday next to Highland Park reservoir. It’s everywhere!!

    p.s. Steve Coleman, peregrine news is easily accessible in my “Peregrines” category here: http://www.birdsoutsidemywindow.org/category/peregrines/ The peregrines are definitely in town.

  18. Sharon Leadbitteron 07 Feb 2011 at 8:04 pm

    BUT ….. keep in mind that the Japanese knotweed is in major use for resveratrol supplements … yes it’s invasive … flowers are kinda pretty though. But at least there is a use for it. Also, alot of beekeepers love it because it’s an important source of nectar when not much else is flowering.


  19. Kate St. Johnon 08 Feb 2011 at 6:55 am

    I wish people would use it a lot & they would keep it in check.

  20. lisaon 08 Feb 2011 at 11:20 am

    Too bad its not more tasty, or it could feed starving millions.

    Impossible to eradicate this pest….short of a flame thrower, and I am not sure that is even enough. I have been chopping at this stuff for years and it just laughs at me and doubles itself……

  21. Tom Maieron 10 Feb 2011 at 1:22 pm

    Looks like Japanese Knotweed.

  22. marygreeneon 24 Jul 2012 at 2:04 pm

    pawlonia tree pawlonia tomentosa
    from asia, over 10 feet tall, hollow stems, invasive, growing in my yard.
    it’s one of P T Barnum’s curiosities and grows wild in all the places the circus travelled
    as elephants have extremely inefficient digestive systems

  23. Kate St. Johnon 24 Jul 2012 at 2:13 pm

    Mary, sorry to hear you’re overrun with Pawlonia. Maybe its twigs have a similar look to Japanese knotweed … but Dianne Machesney, who took this picture, had the advantage of seeing the whole plant & this one is Fallopia japonica (or Polygonum cuspidatum).
    Alas, there are too many plants that are out of control.

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