"Maggie's Mom" wrote:
Two years ago I planted a rose - Mr. Lincoln. It grew
normally, had beautiful flowers, and towards the Fall
it sprouted a strange looking twig with small leaves on it.
I left it alone, curious about what was transpiring.
[...]

If the odd twig came from the base of the rose, particularly
from below the graft union (almost all commercial roses
are grafted), it's sprung from the rootstock, which is probably
of a rose called "Dr. Huey," aka "Shafter." That's sort of
a climber, blooms only once a year, and has red flowers,
not fully double, lighter in hue I think than those of
"Mr. Lincoln."

It's just barely possible that it's a sport, a branch that acts
like a climber, sprung from a mutated cell in a bud of
"Mr. Lincoln." Occasionally such a somatic mutation will
result in a climbing branch on a non-climbing rose, from
which one can take cuttings and propagate what's considered
a new variety. It's not likely but it does happen occasionally.
If memory serves, the climbing form of "Mr. Lincoln" in
commerce showed up in India some years ago.

See where this oddball branch comes from, and what sort of
flowers it bears. If they're "Dr. Huey" flowers you're best
off pruning the thing away. If it's not from the base and the
flowers look like "Mr. Lincoln" flowers, you probably
have a climbing sport -- but again, such things are rare.

Mark.