Puzzle: Purple Passionflower

You could learn more about the Purple Passionflower by clicking here (PDF). I will say, I find it odd that the United States Department of Agriculture would write this on its website:

Purple passionflowers may become invasive in some regions or habitats. To control the spread of purple passionflower, remove the suckers regularly.

I can’t figure out if “suckers” is an actual part of the flower or if it is used pejoratively.

Photo by Robert Fernandez