Not sure. Is this one of those topiary types which has the top grafted onto another tree of a similar species?

Ummm...I am not sure? How would I tell this?

Does it have a straight trunk and is there a bulge where the crown meets up with the trunk? Like one part of hte plant, enveloping another? If so, it's a grafted tree. The base is not the same as the top portion of the plant. The base may be a simple mulberry tree but do be careful if you are considering to grow the bottom part as regular mulberries can grow to sizes of gigantic proportions.

Here;s a link to a photo of a typical grafted mulberry standard. http://www.tree-mendus.ca/Mulberry.jpg

Many garden stores will sell many forms of standards that are really grafted to trees of similar species. Like apples to apples, pea shrubs to pea shrubs, lilacs to lilacs, etc... To be certain, check for hte graft union portion. That is the area that requires most winter protection because once that area is injured either by water seeping in, or an insect burring in, fungus, etc.. it will kill off the top portion of the plant. Also with any grafted tree, there will always be situation where the bottom part will try to grow more branches or trunks. It's important to suppress these growth because it takes nutrients away from it's head. It's akin to Frankenstein.

Is a weeping mulberry always grafted or are they a separate species. If they are always grafted how do you graft them and what onto