Where is the cork bark elm from? I mean where is it native too, I guess its not from America, unless I just have never seen one before. Its a great looking specimen, seems like an ancient big tree from the picture already.
Good luck with this tree.
ed
These trees are not native trees. They are sports from the Hokkaido elm. They were propagated by Carl and Shin Young in Chico California when they ran the USDA quarenteen station in Chico. There is a plaque at the site still today that talks of Carl and Shin and thier contributions to the nursery trade.
About these trees. I am pretty sure propagation is by cutting only as they are sterile. Of the three, yatsabusa, corticosa and seiju, I know seiju and corticosa is I am not sure about yatsabusa.
The natural tendency of these trees are to grow inverse taper rather easily. This fact alone has kept them out of the "specimen" classification as bonsai. This, coupled with no apparent reason branch die off, and branches snapping easily while wireing makes them rather difficult bonsai subjects.
The only differences between the look of the trees when seen together as a group of three is the shape and length of the leaf. All three are small and deep green. The leaves tend to have very short internodes with leaves almost growing on a ridge on each side of the stem, looking like small swords.