It is only rootstock if it emerges from below the graft. I'd still be tempted to remove an overly vigorous shoot. You could just head it back and force some side shoots.

Such vigorous shoots are quite common and called 'water sprouts' or 'water shoots'.
You can prune them away if you feel the balance of the tree is being upset.
Or you can use them to increase the height of the tree. They do take a couple of years to settle down, but will eventually revert to normal and produce flowers and fruits.

The link below almost completely answers your questions. Do make sure that your tree is getting enough light, as it will otherwise grow leggy (as suggested in the link).

What happens to me is that many of the branches bow over with fruit, which exposes underneath branches to light. Some of the branches seem to take advantage and shoot up to fill the void. I figure this is basically a natural growth pattern, so I just prune them to shape or let them be if they are not too unruly.

Here is a link that might be useful: Problem Solver: Pruning Dwarf Citrus

Thank you for the comments! I hate to prune them off; they are so gorgeous... but yes, they do make the tree look unbalanced. And I'm worried this branch might be taking something from the rest of the tree.

You think you have problems, apparently my entire dwarf meyer lemon tree is a root stock, meaning each and every branch is a root stock. I still don't know how this could have happened.

Here is a link that might be useful: lemon photo link

tropical thought, this can happen by not triming off branches that sprout below the graft line. Look to see if all the branches are coming from below your graft line. If this is the case, then yes, your tree would be all rootstock. If, however, you have branches above the graft line, then you have your Meyer lemon tree. It's possible to have a combination of both. Look carefully. If you can post photos of close ups of the trunk at the graft line, we can help you to determine if this is the case or not. If you allow rootstock sprouts to grow, they will overtake the graft, as rootstock is very vigorous. You can also tell by the shape of the leaf. Most like, you've got some sort of trifoliate rootstock. If the leaves are in three's, then you've got rootstock growing. If they look like Meyer lemon leaves, you've got your graft growing. And, if you post the .html code directly into the body of your message, your photos will show up right in the message. A bit easier for us to evaluate than a link.

Patty S.

This is to hoosierquilt, from last summer, and they suggested
posting photos of the Meyer Lemon leaves, and trunk. I am not sure where you want me to post the photos, as normally I would email attach them or upload them to a server, but I am not sure where that is. If it is evident, I will do that for you. Otherwise, if you give me a site to send them to, I will do that too. I suspect this has returned to root stock. Not sure what I should see or not in the leaves, but they do appear to be in three's. Thanks for the help. My
email address is reism@cox.net Thanks, Mike

Additional information - posting to galleries at this website 5 photos. Also lots of nasty thorns are all over the branches and stems - not any blossoms or fruit - NONE. This was a very small tree when I bought it - like 2-3 feet tall, got 1-2 lemons first year or so, but never again, and we had a bad freeze last winter, and that may have hurt it too.

Mike, upload your photos to a photo sharing site like www.photobucket.com. Once uploaded, copy the HTML code, then paste that code directly into the body of your message. Your photos will then be embedded into the body of your message. You'll know you did it correctly by clicking "Preview Message", and your photos will then appear in your message.

Patty S.