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5818 Views 9 Replies Last post: Jan 4, 2014 8:33 PM by MikeHardman RSS
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Dec 28, 2013 9:35 PM

black poplar or hybrid ?

I have recently moved into what was formally an office building in a sand quarry in Bedfordshire. In what is now the garden is a lovely old tree which so far I have managed to identify as a type of poplar. It seems to have all the characteristics of a 'populus nigra' except that it's not living near water ! What I have picked up in my internet searches is that there are many hybrid versions so Im wondering if anyone here can help make a more accurate identification.


Unfortunately its trunk isn't in the best of health. In some areas the bark has come away cleanly. In others areas there are some deep fissures which have a black interior. Near the base are some holes that look like those caused by a hornet moth. Higher up some of its limbs have been torn off roughly by a previous inhabitant of the building. Should I do anything about these defects or will it somehow survive these attacks ?DSCN2510.JPGDSCN2526.JPGDSCN2525.JPG

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    Dec 30, 2013 9:32 AM (in response to capt a)
    Re: black poplar or hybrid ?

    It may be Populus trichocarpa (black cottonwood) or P. nigra (black poplar), or (least likely) P. deltoides (eastern cottonwood).

    It is difficult to be sure because there are hybrids and cultivars, with intermediate characters (and some of the characters, such as leaf shape, vary within species).


    Have a look at these references and you may be able to decide (let us know).

    You may need to consider characters which cannot be seen at the moment, eg. catkins.

    When considering leaves, note that there will be a degree of variation, even on your one tree. So look at quite a few and try to bear in mind the range: of size, of acuteness of the tip, and of serration of the edges. The one you (nicely) photo may be unrepresentative in having an obtuse tip (?).


    P. trichocarpa:


    P. nigra:$file/RIN239.pdf


    P. deltoides

    (note the trembling of the leaves because of their flat stems)

    See this for comparison of leaves of Pp. deltoides and trichocarpa



    Just for a bit of completeness:

    If they were balsam poplar (Populus balsamifera or P. x gileadensis), see if you notice a sweet scent in the air in spring, and pinky spring leaves -



    Don't be swayed too much by the conditions that it is growing in. It is cultivated, so nature is not making its natural choice. Also, poplars can have agressive roots - so,unbeknownst to you, it could be tapping into a source of water such as a sewer.


    They are tough, so it will probably recover as it is (though they can get fungal diseases).

    But I note the section coming close the the building. I would be strongly tempted to take the top off the trunk where it makes its first slight kink towards the building; just above where the new shoots are arising. That would allow the new shoots to develop into branches, forming a more symmetrical crown, and being further from the building. It would also remove the damaged section higher up.

    ...Like this:


    Be careful not to damage the remaining trunk: it would be easy to rip a section off. Use the normal arboricultural practice of doing the removal in stages from the top down, and making a sub-final cut starting on the underside a couple of feet up from the final one. Then there will be minimal weight on the final cut (which should also be started from the lower side).


    As the new shoots extend, you will need to do some thinning, progressively over a few years. That will allow you to develop a well-shaped main branch structure and hence a pleasing crown.


    You could also find new shoots arising from the base. They would be best removed as soon as seen (you can rub the buds off with your finger/thumb if you catch them small enough). That is just to preserve a satisfying shape for the tree (nothing to do with grafting/rootstock issues as with some other trees). Once the top growth has developed (back in sympathy with the size of the root system), new basal shoots should become rare.


    Let us know what you think about the species, what you decide to do about the pruning, and how things progress in future.



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      Dec 30, 2013 11:17 PM (in response to MikeHardman)
      Re: black poplar or hybrid ?

      Hi Mike,


      Ik las dat je uit Nederland kwam! Is dat waar? Want ik doe.



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          Dec 31, 2013 9:37 PM (in response to capt a)
          Re: black poplar or hybrid ?

          You should be able to find some old leaves on the ground, amongst the grass, for instance: they will still indicate whether the leaf stem (petiole) is flattened or not. You would not be able to roll a flattened one between your fingers; an unflattened one, you would. Your description of it rustling and quivvering strongly suggests the petioles are flattened.

          If the petiole is flattened (I can't tell from the extra photos, but thanks anyway), that suggests either Pp. deltoides or tremula. But neither of those fit your tree. The lack of acuminate/acute tips rules out P. deltoides, and there are various factors such as lack of wavy margin that rule out P. tremula. But alternatively it could be a hybrid, including one or both of those species - hence the expression of that trait.


          I think we may need to be patient, Gerry.

          There's a good chance it is a hybrid and/or cultivar, so be prepared (as I think you are) not to get a precise ID even then.


          Whichever it is, you can treat it the same way.


          Oh dear - now we've got some cuttings rooting!

          Where are you going to plant those? (Or are they just for experiment/observation?)

          If you have somewhere in mind to plant them, best to do it sooner rather than later - as some species that root readily in water can die when planted out if they have become too accustomed to the water. Planting soon after root initiation gives them the best chance of establishing a wide-spreading and deep root system - essential for the health and long life of the tree. Just bear in mind that many Poplars have roots that agressively search out drains and septic tanks, and can cause damage to concrete through heaving, be it direct (roots physically) or indirect (hydration/dehydration of the soil).


          Happy New Year,


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            Jan 2, 2014 5:29 PM (in response to MikeHardman)
            Re: black poplar or hybrid ?

            Just while I think of it...


            1. The hybrid black poplars have the botanical name Populus x euramericana (syn. P. x canadensis),

            which covers all the hybrids that have arisen between P. nigra, deltoides and angulata since about 1700.

            So, if we decide yours is somewhere in that lot, you'll have a name to use.


            2. P. x euramericana 'Regenerata', is the only one that has obtuse tips to the leaves ('short acuminate or obtuse'), out of those mentioned by the veritable Alan Mitchell ('A Field Guide to the Trees of Britain and Northern Europe', Collins). But it is a female clone, so it would definitely produce catkins and then 'wool'.



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                Jan 4, 2014 8:33 PM (in response to capt a)
                Re: black poplar or hybrid ?



                Good field work and photos.

                I note that some of the leaf tips are acuminate.

                This is looking close to P.deltoides to me now.

                Some more links




                And there are male clones (no fluff).


                You raise a good point about the engineering of the leaves /petioles.

                ...To which I don't have an answer. I, too, can only muse at what evolutionary advantage the propensity to flutter offers. Phormium leaves have a similarity in the orientation of the petiole flattening at the point of unfurlment. Consider some palms, too.

                Leaves in general are worth studying for their engineering. There are lots of neat tricks awaiting discovery by the inquiring mind. One plant that is quite well known for its leaf engineering is the giant water lily, Victoria amazonica (I won't say any more).


                And to any body interested in engineering and the natural world, I have one word for you - biomimetics!



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