I have a 3-4 yr old smooth hydrangea that suddenly grew what looks like an oak leaf hydrangea stem. The main shrub has not begun to flower yet this year, and I thought the stem was a separate plant. I looked at the main stem and this one is growing off of it close to the ground. It was ness as rly a foot taller than the roughly 3 foot plant. It was strange looking so I cut it back to the level of the other leaves. I have had this happen with grafted roses but the stem comes out closer to the ground. What could this be?