Identification: What variety of Japanese maple is this

Discussion in 'Maples' started by fiddick, Jun 16, 2021.

  1. fiddick

    fiddick Active Member

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    Hi All,

    hopefully someone can help me out. I live and garden in Orillia ON, Zone 5, but I bought the maple in question in the suburbs of Vancouver. I was looking for Shirasawanums because they seem hardy enough here. The maple in question was labeled as a Shirasawanum and the variety was given as well. My recollection is that the variety name began with an M or N, but I could be wrong about that. Anyway, this maple is totally unlike any other Shirasawanums that I've been able to find online, but I still think it's a Shirasawanum because it's come through several winters here unscathed. I'd really like to know the name of this variety, if anyone has any ideas, please let me know. It's kind of unusual for a Shirasawanum if that's what it is (it could also be an interspecific cross) in that it has deeply cut red leaves with a bit of green showing through. Thanks.
     

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  2. maf

    maf Generous Contributor Maple Society 10 Years

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    I don't know what it is, but looks a little like Acer shirasawanum 'sensu'. Not exactly the same as your picture though. Does yours have nine-lobed leaves in addition to the seven-lobed ones pictured? As it stands, relatively few leaf lobes for a shirasawanum, so likely an interspecific cross as you mentioned.
     
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  3. fiddick

    fiddick Active Member

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    I think I might have looked at Sensu online before and dismissed it as a possibility because the coloration doesn't seem right. The photo doesn't really give the best impression of the color on this. The leaves tend to be more purplish. However, that might have something to do with the growing conditions and it's maturity. I have this planted not in deep shade, but for the most of the day a large Norwegian maple is blocking the sun. Most of the sun it gets is in the early morning and perhaps late afternoon. In the spring, the leaves emerge very reddish (the purplish color that you see in Bloodgood, for example, but a shade lighter). This year the leaves seem a little greener, so maybe with age they will get greener still and look more like Sensu? But right now, the leaf colour looks quite different from that in any Sensu picture that I've seen.
     
  4. Otto Bjornson

    Otto Bjornson Well-Known Member

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    that really looks like an Acer Palmatum " trompenburg". What are your fall colors?
    similar growth habit to the shirasawanum as well
     

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  5. fiddick

    fiddick Active Member

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    It does look a bit like that, but somehow from other photos I've seen it looks a little off. The colours of trompenburg seem more vivid -- but photos vary so who knows. How vigorous is trompenburg? The plant that you see in the photo is over 4 years old. I bought it in 2018. It was more than a seedling then, but admittedly not too big. My sense is that A. palmatum grows much faster. And the slow growth isn't due to winter dieback -- there has been none. However, it is in somewhat dry shade. The Bloodgood behind it has likewise not really grown much in nearly 10 years, so the slow growth might be due to sun and soil conditions. As for the fall colour, my recollection is that it wasn't all that noticeable. Or perhaps the better way to put it is that it wasn't all that memorable because I can't remember, whereas I definitely remember the colours of my A. pseudosieboldianum, A. s. aureum, and Bloodgood. Again, this could be due to the conditions under which it is growing. How hardy is Trompenburg? I seen that it's hardy to zone 5, but I'm borderline zone 5, I think, and that's Canadian zone 5, which tends to be colder than the US zone 5 I think. It's been hit and miss with Bloodgood and Emperor 1 in my yard, some make it, some do not. But as I said, the Bloodgood planted right behind it has had no problems surviving at that particular site, though with next to no growth. Then again, we get fairly reliable snow cover here and the tree is fairly small. I'll try to have a look today if any of the leaves have more than 7 lobes. I take it if any of the leaves have 9 lobes it's more likely to be a Shirasawanum than a Palmatum. If they are all 7, is it more or less a sure thing that it's Palmatum (or a cross with it)?
     
  6. Otto Bjornson

    Otto Bjornson Well-Known Member

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    trompenburg was one of the varieties we grafted for years. Although it is an upright cultivator, it is a slow grower and tends to expand more horizontally. Makes for a nice tight landscape tree. And the colors can vary depending on your location and amount of sunlight. We found all of our grafted trees were basically all equal in hardiness with the palmatum root stock. We grafted an ongoing variety of approx 30 different cultivators every year. Tried to stay away from the usual suspects as we created our own niche with unusual varieties. But of course Bloodgood is a great larger landscape variety which always was a good seller for us as well.

    Also, regardless of the variety, a japanese maple is only going to grow based on the quality of the sine wood attached to the root stock. And that can lead to many variations from what you might be expecting from a text book.
     
  7. fiddick

    fiddick Active Member

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    I'm curious, are you a wholesaler or a retailer? I bought this from Aarts Nursery in Langley. If you are a grower, perhaps it is something you supplied to them and it got mislabeled.
     
  8. maf

    maf Generous Contributor Maple Society 10 Years

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    A pure Acer shirasawanum would have 9-13 leaf lobes. Both 'Sensu' and 'Trompenburg' have 7-9 lobes and are widely believed to be hybrids between shirasawanum and palmatum despite the fact that one is listed in books under shirasawanum and the other under palmatum.

    I don't think it is 'Trompenburg' in any case as I don't see the rolled under leaf lobes which are a defining characteristic of this cultivar, but what is interesting is that all the suggestions are pointing towards an interspecific cross even if the exact one has not been identified yet.
     
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  9. fiddick

    fiddick Active Member

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    I've been out to check the plant. I couldn't see any leaves with more than 7 lobes, so it can't be a pure Shiraswanum. It probably has some Palmatum in it even if it isn't a pure species. Yes, that was one of the other things I had notice in the photos, the rolled leaves. Mine might have had that when they were first coming out, but they don't really have that now.
     
  10. MapleMO

    MapleMO Contributor 10 Years

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    When I saw your picture, Sensu was the first one that came to my mind as well. This is a photo of mine taken about a week ago.
     

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  11. fiddick

    fiddick Active Member

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    This is quite different, especially at the tips. The new leaves at the tips never look lighter like this on my plant. By the looks of this photo, the new leaves on Sensu are pale then darken. If anything it's the reverse on my plant. They start purplish red, then fade a little as some green develops. The green also seems more pronounced this year compared with previous years. I don't know if this is due to the age of the plant or changes in its growing conditions. I bought another tree a couple years ago, unlabeled, and couldn't for the life of me figure out what it was. I thought I was possibly buying a cutleaf sieboldianum, but got it home and the leaves didn't quite seem right. (I should explain that some of the maples I bought, not this one, were from a local botanical garden where they had posted the available varieties online, so I went with my list, but a lot of the plants were unlabeled and the overseer wasn't in that day, so took my chances in the hope they were what I had set out to buy). Then low and behold this year the branches all started weeping and I figured out that what I have is A. p. Omure yama. Anyway, I'm watering the tree in question more consistently this year and the added growth seems to enable it to get more of the afternoon sun as well, so maybe it now is showing or will start to show its true nature.

    Regardless, when I bought it, it was sold in a section of the nursery where they were selling smaller, rarer plants -- so just one copy of each. I wouldn't be surprised if it is some nonregistered variety. I also wouldn't be surprised if it was mislabeled -- these things do happen. Meanwhile, if anyone reading this thread has any ideas on my other maple (posted in a different thread), bought at the same time as the Omure yama, which I had thought was A. pseudosieboldianum takesimense, I would really appreciate it...
     
  12. ROEBUK

    ROEBUK Contributor Maple Society 10 Years

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    We can safely say it's not Trompemberg , here's some of pics of my Trompemberg then a few of my Sensu from this evening.
     

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  13. fiddick

    fiddick Active Member

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    In the Trompenburg photo, how old are those leaves? Is that what the look like when they first unfold, or are they more mature? Regardless, that quite different, darker, than the leaves on mine. But they are a little more like this when they first emerge.

    I had this vague recollection that the name on my tree was something like M... Ninja when I bought it, but when later google searches for "shiraswanum ninja" turned up nothing I gave up on that idea.
     
  14. fiddick

    fiddick Active Member

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    Actually, I'm wondering if it might be A. s. Royalty. Anyone familiar with that? Does it ever get some green on the inside of the lobes?
     
  15. ROEBUK

    ROEBUK Contributor Maple Society 10 Years

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    Well they are new spring growths, comes out this colour every year , the other cultivars you have mentioned i don't think they are in the UK at this present time so can't comment on those.
     
  16. Otto Bjornson

    Otto Bjornson Well-Known Member

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    We were a small operation, only sold direct to customers between 1991 - 2008.
    The trompenburg will open up in spring with a very deep purple tone leaf, just like the image from @ROEBUK
    However, they do turn to the more bronze / green tones thru out the summer months. And even more on the green side with limited sun. Crimson fall tones of course
     
  17. maf

    maf Generous Contributor Maple Society 10 Years

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    Knowing you think the name might start with "M", could it be "Mirte", listed in books as palmatum but I have heard of people buying it under shiraswanum in continental America. Looks like a hybrid and known to have pubescent foliage in the leaf out stage which is a shirasawanum trait. (7-9 deeply divided leaf lobes.)
     

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