Rhododendrons: Brown leaves - feature or symptom?

Discussion in 'Ericaceae (rhododendrons, arbutus, etc.)' started by wcutler, Jun 8, 2019.

  1. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    My neighbour asked me about this rhododendron at the Parks Board Office right at Lagoon Drive, with such nice brown leaves. I don't think she even mentioned the white flowers, which now are pretty much finished. I don't know why she wants the ID, and I told her that would be impossible. But I'd like to clarify that the leaves are supposed to be green, is that not the case? The leaves at the back that are fully shaded are green. The brown colour is sunburn?

    I checked the Parks Board document at https://vancouver.ca/files/cov/ted-and-mary-greig-garden-50-rhododendrons-of-interest.pdf, don't see a good match for this. Flowers seem to be completely white, no splotch. All parts are hairy, but no indumentum or tomentum.
    Rhody_ParkBoardOffice-at-LagoonDr_Cutler_20190608_173718.jpg Rhody_ParkBoardOffice-at-LagoonDr_Cutler_20190608_173747.jpg Rhody_ParkBoardOffice-at-LagoonDr_Cutler_20190608_173936.jpg Rhody_ParkBoardOffice-at-LagoonDr_Cutler_20190608_173957.jpg Rhody_ParkBoardOffice-at-LagoonDr_Cutler_20190608_174047.jpg
     
  2. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Another neighbour, a walking companion of the first-mentioned neighbour, just sent me these photos taken May 27, which give a better idea why they describe this tree as a brown-leaved rhododendron. Some of these photos show a possibly yellow splotch.
    Rhododendron-BrownLeaves_DaveG_ParksBoardOffice-Pendrell_20190527_image1.JPG Rhododendron-BrownLeaves_DaveG_ParksBoardOffice-Pendrell_image2.JPG
     
  3. Margot

    Margot Generous Contributor 10 Years

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    I've never heard of brown-leaved rhododendrons before. Some rhodos do have indumentum or tomentum on their leaves which many give a brownish appearance but the green still predominates. To tell the truth, I see nothing alarming in the photos above. The bronzy cast to the leaves looks like a the normal colour new leaves on many rhodos exhibit when they first unfurl. I have one whose new leaves are dark maroon. As the weeks go by, they become green.

    I will see if I can find out more from other members in an ARS society I belong to and report back in the next day or two.

    Quote from Henning's Rhododendron & Azalea Pages
    "Indumentum (pl. indumenta) is a general term denoting the covering of hairs found on the underside of the leaves of many rhododendrons. On rhododendrons, indumentum is commonly a woolly covering on the underside of mature leaves, while a similar surface on the upper side of leaves is called tomentum."
     
  4. Ron B

    Ron B Paragon of Plants 10 Years

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    It's 'Martha Isaacson'.
     
    Last edited: Jun 9, 2019
  5. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Wow, thanks, Ron! That is an Azaleodendron, as you suggested before editing your reply with the cultivar name. Henning's has a page with some info about Azaleodendrons at
    Henning's Rhododendron & Azalea Pages.

    The first page I looked at for 'Martha Isaacson' says "Flowering in May, it has unusual evergreen foliage that is tinged deep maroon."
     
  6. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    Margot, I'm happy to see that a member of the ARS reads this forum. And thank you for your reply.
     
  7. wcutler

    wcutler Esteemed Contributor Forums Moderator VCBF Cherry Scout 10 Years

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    I'm so surprised that I didn't post photos from last year, so here are a few from before the flowers had really opened.
    RhododendronMarthaIsaacson_ParkBoardPendrell_Cutler_20200524_171230.jpg RhododendronMarthaIsaacson_ParkBoardPendrell_Cutler_20200524_171323.jpg RhododendronMarthaIsaacson_ParkBoardPendrell_Cutler_20200524_171428.jpg RhododendronMarthaIsaacson_ParkBoardPendrell_Cutler_20200524_171453.jpg RhododendronMarthaIsaacson_ParkBoardPendrell_Cutler_20200524_171545.jpg

    I've been watching it almost daily this spring. Here are two bud photos from May 21, 23.
    RhododendronMarthaIsaacson_ParksBoardBuilding_Cutler_20210521_143823.jpg RhododendronMarthaIsaacson_ParksBoardBuilding_Cutler_20210523_145038.jpg

    And June 3. Someone in my building came by, who mentioned walking through the Greig Rhododendron Garden with a friend whose husband's aunt is the Greigs' granddaughter. That makes me almost family now.
    RhododendronMarthaIsaacson_StanleyParkBoardOffice_Cutler_20210603_152312.jpg RhododendronMarthaIsaacson_StanleyParkBoardOffice_Cutler_20210603_152356.jpg RhododendronMarthaIsaacson_StanleyParkBoardOffice_Cutler_20210603_152404.jpg RhododendronMarthaIsaacson_StanleyParkBoardOffice_Cutler_20210603_152454.jpg
     
    Margot likes this.

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