Why Do These Trilliums Have a Green Stripe on Each Petal?

Just before or on Mother’s Day in southern Ontario the Trilliums burst into bloom. As I’ve been wandering through the woods this April and May I’ve been trying to take photos of all the types of trilliums I see. Colourwise, I’ve found white and red trilliums. As the white ones age, many will gradually fade to a light pink. The most interesting white ones had a broad green stripe down each petal.

Where Do These Green and White Trilliums Grow?

Photo of White Trillium Green Stripes on NaturalCrooksDotCom

Although I’ve looked elsewhere, so far I’ve only seen these white and green trilliums at Bronte Creek Provincial Park. They are quite striking.

When I looked closer, I found some are almost entirely green. They are less noticeable as they blend in with the green leaves.

Photo of White Trillium Infected Mycoplasma on NaturalCrooksDotCom

According to information provided by Bronte Creek, the green stripe is caused by a virus.
A University of Alberta website cautiously states that the stripe may be caused by a bacteria or virus.

A Michigan State University website on the Painted Trillium is a bit more specific. It says “Trillium grandiflorum (Large White Trillium) … [can be] infected with virus-like mycoplasmas, which are parasitic, subcellular organisms that often result in the normally white petals being streaked with green or pink….” It says this type of infection is “not uncommon.”

The basis of the Michigan comments was a source called “Case.” In a chat about green-striped trilliums, another person says “To my knowledge there has been no direct DNA work done to confirm and expand on the Case, et.al. observation of mycoplasmas in trillium.”

So I’m not 100% sure what causes the green stripes, but the most accepted theory is that it is an effect caused by mycoplasma.

Photo of Red Trillium Lemoines Point On NaturalCrooksDotCom
This is a Red Trillium near Kingston in 2013.

Do Ants Really Plant Trilliums?

I’ve read this idea on websites and in books. I guess it may be true although I find it surprising.

Photo of White Trillium on NaturalCrooksDotCom

Apparently ants collect the seeds from trilliums and take them away from the plant and sometimes underground. They eat only a portion of the seed and the remainder can sprout and start a new plant. (That’s similar to birds eating buckthorn berries, digesting the outer fruity layer, and then shedding the undigested seeds which may grow into new shrubs.)

Photo of Trillium Fading Pink on NaturalCrooksDotCom
This photo was taken last year of a white trillium fading to pink which will soon set seed.

If you’ve seen ants taking the seeds away from a trillium please let me know with a comment. I’ve never seen ants anywhere near a trillium, myself.

Photo of Red Trillium Red Sepals On NaturalCrooksDotCom
This Red Trillium has red on the edges of the green sepals, too.

For now, I will enjoy every shade of trillium I find.

Related Reading

Join In
Have you seen any of these striped trilliums? Or seen any ants toting away the trillium’s seeds? Please share your experiences with a comment.

40 thoughts on “Why Do These Trilliums Have a Green Stripe on Each Petal?

  1. We have trillium striped with green here in Brantford, Ontario long the Grand River. I have seen them in the same area several years in a row.

    • Sounds like another good place to look for them! The virus seems to stay in one area for many years, if not for ever. The ones at Bronte Creek have had this colouring for more than 15 years that I know about.

      Thanks for sharing your sighting!

  2. By the way, the “Case” source you mention above is a really great book on Trillium by two long-time Trillium enthusiasts and botanists, Fred and Roberta Case’s “Trilliums” (1997, Timber Press).

    In it, they describe some work from the seventies where abnormal flowers (like the ones you posted) were examined with an electron microscope. Mycoplasmas (very very tiny bacteria that live *within* host cells) were present only in the abnormal flowers and not in normal-appearing flowers. So right now it’s guilt-by-association. Mycoplasmas also cause “parrot tulips” distinctive flowers.

  3. Today at LaSalle Park in Burlington, amongst a large number of trilliums I saw a single trillium flower with a green stripe down the length of each petal, like the top photo. It really stood out from the normal flowers. I didn’t search them all but if there were more it wasn’t too many.

    • Interesting! That’s another place then where the virus has started to sneak into the trilliums. I saw some at 16 Mile Creek too. Thanks for sharing your sighting!

  4. I would love to send to you some pictures I have taken of Trilliums. How would I do this.

    Sincerely,

    Donna McAdie

  5. Lawson Tract by Ingersoll ON also has a few of these green striped trilliums as well as solid green ones. I just assumed it was a cross pollination thing such as I see in my tulips where the red and yellow start blending when grown together. A friend just mentioned it to me that it was bacteria. Her information indicated that it would eventually kill the plant. Has there been any research into this? Should they be removed from the ecosystem?

    • I couldn’t find much research into this at all. In fact, almost all the websites just quote each other and refer vaguely to the one study that concluded it is probably (not proven) caused by a virus. I haven’t seen any sign of it killing the plants. I personally would not remove them from the ecosystem. I’ve seen enough info on websites to believe that these types of trilliums are quite common.

      If anyone has seen this actually killing plants, please share!

  6. We have the bold green stripe and solid green trilliums in st Ignace mi. Have pictured them for about 4 years

    • I think they may be fairly common although the cause is not 100% studied. They make quite an interesting change from the solid white ones. Four years sounds like it doesn’t affect them too badly. Thanks for sharing your sighting!

  7. August 7, 2018
    Hello,
    Interesting comments. As an avid gardener and former Arborist, I am always on the lookout for unusual plants/trees. I viewed green striped Trilliums in the forests near London Ontario back in 2003. Often wondered if it was an off-shoot of the green variety.
    I I have no other suggestion other than what was offered by others. If you find a BLUE Trillium, let me know…it should be worth a few million!!!
    Al de Koning

    • Yes, a blue one in Ontario would be quite something! I’m not sure how many colour variations there are in the States, though. They have around 39 native species!

  8. Hello Again,
    “Honest Crooks.” This reminds me of a garage in the Pickering area years ago. Guess the name of the operator was Crooks. Above the door of the garage it advertised, “Deal with honest Crooks!”

    Al de Koning

  9. I just found one with green stripes in Waterford MI. First and only one. Glad I found your page. Thought I found a new species! Lol

  10. Longwoods Conservation Area, near London, Ontario. I thought they were quite pretty and am slightly disappointed to learn of the potential virus. Although that is how tulip mania originated in Holland, so sometimes these things add beauty.

    • Thanks for sharing another spot where they pop up. I was reading that there are many more types of Trilliums in the USA than in southern Canada. At least we have these unexpected variations!

  11. I found one with the green stripes last year (2019) in the Geo Time Trail in Clair Hills in Waterloo. I found one again this last week and a friend has seen several of them on this trail. They are beautiful and it was very interesting to discover what causes the change. I thought it might be a new species too! :-)

  12. In my backyard I maintain a small wooded area. For 50 years trillium has grown in one place. over the years I have observed the green striped flower petals come and go along with occasionally double petaled trillium. A storm came though 5 years ago and I lost so many of my trees. To help the trillium I now mulch with extra leaf mulch. The results is that the plants are multiplying generously. I now have a clump of green petaled trillium. So far no double plants have appeared. I was wondering as to whether I should remove the green ones but gathered from above messages that I can leave them. So far they have not spread over the several years since the storm.

    • I’m not an expert but what I’ve read said that it doesn’t seem to be a big problem for the trilliums. I’m glad your patch has thrived with your extra care!

  13. I have found many green-striped trilliums in Elgin County including some with six to ten pedals. As well I have found many deformed red trilliums including ones that looked like they had been smashed with a hammer. I have many pictures of these flowers if you like to see them.

    • Unfortunately there isn’t really a way to share photos, although you may want to post some to a website/app called iNaturalist to record the location. Thank you for sharing your info, though, it’s interesting to realize how widespread some of these variations are!

  14. There are quite a few green stripe trillium in the wooded areas around the Forest Hill Apartment complex
    in London Ontario. I have found 2 mutant varieties – an almost all green one with 4 petals and a completely double one – 2 sets of three petals – absolutely stunning!

  15. I just noticed the green striped trilliums this year in Horseshoe Valley. Some had and extra set of green petals and this seems to only be occurring on the ones that are fully green or almost fully green.
    I also noticed that the leaves that held the pod before the trilliums bloom are much broader.

  16. Need to know if it is illegal to transplant trilliums? I have done this so many times and replant them in my bush. They are growing fine. A lot of times construction companies just dig up everything. I like to save them.

    • I think plant moving is controlled at local levels. Here in my town, it’s not legal to move them from a city park without permission. But I think it varies from place to place. In most cases, plant rescues are usually given permission. Good luck in your area and I’m glad they are thriving.

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