Jonathan,
Who was the source of your BJ?
I would confirm that it was actually a (rare) fig-graft with them.
LSU Purple is recommened as a fig root stock since it is
(as claimed by LSU) nematode (rkn) resistant.
Hope this helps,
George (NJ).

The source? I bought it at a retail nursery in Las Vegas, a large one, NOT affiliated with the chain nurseries at mega-retailers. I cannot remember its name though. I hope this helps.

Why do you call it a "rare" fig-graft? Is there somewhere I can read about this?
Thanks
Jonny ;-)

RE: "Why do you call it a "rare" fig-graft?"
Figs are usually mass propagated (commercially) using the
'cutting' method. Air layering (for low volume, quick, sure results), may also be used.
Grafting is usually done (in other spieces) for dwarfing (or opposite); hardiness;
or root resistance to certain deceases specific to the spieces.
RE: "Is there somewhere I can read about this? "
I do not know of any...

As an example, most (maybe all) French vines (grapes) are grafted on an
American wild rootstock which is resistant to an
European grape root disease (cannot remember the exact name - do your Google work)...

I missed one important reason for grafting.
It is that if that particular 'cultivar' is stubborn to propagate
otherwise...

Gorgi:
So would a Jack Black fig fall under the catagory of "very hard to propagate" and thus be a likely candidate for grafting?

I have one UnKnown of the 'BJ' type, and I see nothing unusual about propagating it...
Also, another reason for grafting figs (which for most of us is not possible), is fig-breeding (YES, seeds from cross-pollinated fruits). Rather than waiting an 'x' number of years for the (1000's of) seedlings to bear (some good) fruit; buds/stock maybe grafted onto mature fig trees to speed things up.

Gorgi
So what's your guess? Is it possible that this BJ is a graft? Of course what looked like a graft could have been a result of the main stem being completely broken, and a new leader shoot taking over from the side.
I looked at it again, and there is no way to tell one from the other, because it happened long ago.
If it is a graft, I certainly would be happy to know it was a LSU fig. I'm in Texas, and that type of fig should do well here, maybe even better than the BJ fig which struggled from day one.
I could take a photo if you like and show you what I mean

I very seriously doubt that any commercial operation would graft figs. Grafting is more labor intensive than just sticking a cutting in dirt, which is all it takes to propagate most figs. Also, figs frequently send up new shoots, and are sometimes killed to the ground after a hard freeze (like yours) and re-sprout from the roots, so it would just not make any sense to graft. Wait until new growth comes up and post a picture of the leaves on here and someone will likely be able to tell if it resembles black jack.

Kiwinut:
Hey that's the kind of response I need.

As I said in the first post "it looked like it was a graft."

I was not certain by any means. After hearing what you and Gorgi have said, I have to agree that it probably is not.

I'm happy either way.

I'm glad knowing the BJ fig I bought is coming back. If you both said something different, and indicated it was a graft on something like an LSU. That would have been great too. Since those are good figs for my area, and are supposed to be tasty.

I just wanted to know what the plant growing from the roots most likely was, a volunteer from the rootstock, or the original BJ tree growing back from its roots in order to take care of it the best I can as it recovers and grows back.

Just yesterday I discovered that my fig Petite Negrone has two new branches that have absolutely different leave shapes then other branches. I even wanted to post a question here if it's possible. Now I assume my fig could be grafted and because I planted it very low (it grows as a bush, not like a tree, in a pot), the rootstock is sprouting. I will wait and see if I will have two different fruits on one bush - I hope so.
Yelena

As kiwinut very clearly pointed out, because of freezing issues (a sure top dead for figs, sooner or later) fig
grafting is not desired for us up (winter cold) north.

yelena,
Figs are curious in that the same plant will carry various shaped leafs. Usually this variation is limited to the number of lobes, but the difference can be quite stark between older, mature growth versus young, vigous growth to the point one might think that the leaves represent two different varieties, e.g. the difference between leaves on the main trunk vs. leaves on suckers growing up from the base. It's very doubtful that you have a grafted fig, unless you did the grafting yourself.

Gene,
Thank you for your response. Leaves are absolutely different in shape: with a lot of lobes and with no lobes at all. I really don't care about leaves as long as I will have ANY figs, the more rhe better (never more than 6 fruits).
By the way, during my garage sale last fall, one old Italian man wanted to buy my fig (I keep pot by my garage) because it has very unique leaves. I gave him cuttings and he was really happy.