I almost had a theory that plum trunks twist up to the left, while cherry trunks twist up to the right. This is not all that clear on young tree trunks, particularly for cherries. From my evidence, it looks like for plums, I can only claim that Prunus cerasifera, the ones on Vancouver streets, twist up to the left. I will show the exceptions last. This will take at least four postings. I invite postings demonstrating instances where my theory does not hold up. I will first show various cherries with trunks twisting to the right. Cherries 'Shirotae' - these trees are either ungrafted or low-grafted. The trunks are 'Shirotae' (2nd and 3rd are the same tree) 'Tai-haku' - the twist is most evident in the limb on the left 'Somei-yoshino' Oshima Cherry and 'Shifo-fugen' (above the graft line)
More cherries Prunus avium rootstock on 'Kanzan' 'Pandora' (particularly note the limb on the left), 'Accolade' and 'Ichiyo' 'Akebono'
Now left-twisting plums. Prunus cerasifera. I do not know how to distinguish ornamental plum cultivars. The first photo is the bark example festival blogger Jessica Tremblay used in one of her write-ups on distinguishing cherries from plums: Plum Trees vs Cherry Trees: How to tell - Vancouver Cherry Blossom Festival She has two other write-ups: Cherry versus Plum Blossoms: What's the Difference? - Vancouver Cherry Blossom Festival How to tell the difference between cherry trees and plum trees (infographic) - Vancouver Cherry Blossom Festival The first photo is from Bob Loveless; second Joseph Lin, third Chorok Kim (that whole tree had white flowers). The rest are my photos. These are not hard to find. I found three in the first block from my place. Here are some big old plums.
Now for exceptions. The most problematical is the Lindsay plum, because it's the same species as the ones above - Prunus cerasifera 'Lindsayae'. This is Jen Dawes's photos from Victoria. It seems to be twisting to the right. Cropping this does not give me a closer photo, just a smaller one. Prunus 'Blireiana', from Jen Dawes. Prunus salicina. These plums already break the rules by flowering in what appear to be umbels of two. And the bark is marked with lenticels, more like cherries. The second is from Joseph Lin and was identified as being Prunus salicina or an orchard cherry that may involve that species.
I didn't include 'Kanzan' above, except for its rootstock. I think this dead tree is 'Kanzan'. For sure it was a cherry, either low-grafted or not grafted. This is a good example because where bark is gone, the twist to the right is particularly evident.
