"Bittersweet" is one of my favorite things to decorate with in the fall. Sometimes it grows prolifically, but in the last few years I have only been able to find a little, so I have been careful not to pick too much. I have seen it grow as a vine, climbing other plants, or it will take a bush-like shape. It look unremarkable in the summer, and I admit that I have never seen the flowers. In the fall it has deep orange berries in clusters.
Here is a sketchbook page I did when I first picked some earlier in the fall.
And here is a very poor picture of what it looks like after the leaves have fallen. The outer hulls on the berries sort of peel back and the berries have sort of a segmented look with lines like a cross over the end.
A google search will probably yield more beautiful photos and better information than what I can give, but I wanted to show it since I referenced it in my last post. I actually didn't use it very much in the arrangement that I showed because I only picked a few stems of it. The red berries in those photos are wild rose hips.