Sort of a cane-growing type, that renews and continues itself from the base - this is probably your most important shoot so far to keep.

I agree, mine is doing the same thing.

Mike

I would have been surprised if the answer was "sucker, cut it down", but you never know. The first two years they grew so poorly I thought they may not survive. Glad to see it growing and will leave it alone.

In general, for pruning, are they like a hydrangea? Take out old stuff every few years? Never more than a third.

I wouldn't cut that much, that often, with either.

Are we talking about Callicarpa? These should NOT be pruned. Most pruned Calicarpas lose their natural shape forever, just like Viburnum bodnantense, another tricky shrub. If you have access to it read Cass Turnbull's book about pruning. There is a chapter there devoted to tricky shrubs like Callicarpas. And remember that it will eventually reach 6x6 feet so be sure you have room for shrub of this size without constant need of pruning it.