Plums do not have thorns, but do have fruiting spurs that may look like thorns. A true thorn will not have buds or leaves growing on them. A fruiting spur is short and can be pointed but will have leaves and tends to be where they put on their fruit. I would take a branch with the leaves to your local Agrilife extension service. They should be able to identify it or at least send off pictures to their experts to see what it actually is.

Sour cherry trees can pollinate sweet cherry trees. I'm not sure if they make the best pollinator, but they are certainly capable of doing so. If you take a cherry that resulted from a blossom that was cross-pollinated here and take out the seed, that seed can grow into a hybrid tree, which can eventually produce fruit of its own (I know that in the case of the hybrid cultivar 'Mesabi' it's even self-fertile). However, the seeds inside this fruit are sterile and cannot grow. Like breeding a horse and donkey together to create a mule, there is no third generation. The reason is a chromosomal difference, sweet cherries are diploid (2n=16) while sour cherries are tetraploid (2n=32). A hybrid between the two results in a triploid cherry, which is why it cannot further sexually reproduce. However, flowering cherry species just happen to have the same chromosome count as Prunus Avium (i.e. sweet cherries), so that means they are capable of freely interbreeding. But it should be noted the two are still not in the same species. The question then is what does this really mean? Even when it comes to the different wild varieties of Japanese flowering cherry, oftentimes crossbreeding them together results in a hybrid that grows less vigorously than its parents, or is not very well adapted to its environment. Sometimes this may become more evident several generations down the line (you might read up more on how Outbreeding Depression works). Cultivated varieties of flowering cherry, almost all of which resulted from hybridization over hundreds of years) are much less hardy than their original wild pure-species relatives. We can even see some level of graft incompatibility combining different varieties of cherries within the same species, the tree does not grow quite as vigorously or as big as if it were grafted onto its own rootstock.

Hi there! Kwanzan flowering cherries are quite spectacular in full bloom! If I may recommend something rather drastic: You might have to re-plant the tree to another location--preferably one that is facing east. Should you decide to do this, it would be a good idea to inoculate the exposed roots with mycorrhizal fungi. The mycorrhizal fungi provide beneficial bacteria that increase the uptake of essential nutrients for the strengthening of the root system and the tree as a whole. I would first dip the exposed roots in the liquid form of the fungi and then just before covering the roots, rest at least four packets of the solid form of the fungi upon them. Garden Gro http://www.thegreengro.com/ sells the liquid form and Xtreme Gardening http://www.ebay.com/itm/Xtreme-Gardening-Mykos-10-gram-Root-Paks-20-ct-/150964902917?pt=LH_DefaultDomain_0amp;hash=item2326359c05 sells the solid form of the fungi. Then again you might be placing too much stress on the tree by transplanting it. In that case, i recommend using the powdered or liquid form of the mycorrhizal fungi by green gro and inoculate the tree's roots simply by adding it to the top soil. Also, you might want to think about purchasing another variety of cherry blossom that is better suited to thrive in your climate zone. "Pink cloud" is a type of cherry blossom whose flowers are similar to that of the Kwanzan and seems to tolerate heat and humidity better than most flowering cherries. http://www.lecooke.com/cms/component/content/article/88-ask-the-grower/367-pink-cloud-flowering-cherries.html I truly hope this info helps. Cheers! Best.

Hey Lena. I love sour cherries.. I call it my childhood fruit.We make jams from it and some tea and syrup with fruits inside .your tree looks good.I am unlucky since zone 7b does not really good for growing cherries.You can check rain tree nursery or trees of antiquity or rolling river nursery,I got couple trees from them.they ship it small though but very very healthy. 2 years ago , I got big size trees like 5 6 feet tall from Willis orchard ,they sell really big trees,at first it looks healthy but all of them got diseases and had to pull them out,so stay away from them and ty ty nursery...