Mystery Plant

We have a community garden in Salem, Ma. We have 99 raised beds on top of a tennis court surrounded by a chain link fence. This plant is growing up the fence just outside of the gardens. It is next to a marsh. There was also some wild asparagus growing nearby. We are not sure if this is rhubarb maybe?Attachment 759Attachment 757Attachment 758

I am not sure what it is. I suspect a weed.
It is definitely NOT Rhubarb.
Rhubarb forms a clump of thick stalks, on the top of each stem/ stalk is a single large leaf. The stalks are often red. ( This is the part you pick and eat) See....

rhubarb plants - Google Search