What is this plant?

Looks like trees to me. Look to nearby trees and compare leaves.

They kind of look like young castor plants. If they are be sure not to let anyone eat any part of them as they are highly toxic. They are fast growing and grow over 6 feet in our area. Here's a link. http://poisonousnature.biodiversityexhibition.com/en/card/castor-oil-plant-castor-bean .

If you click on this link and it takes you to a page that doesn't load. Try taking off the "/div" that might tack onto the end of the link.

Hope this helps.

Looks like the maple family. Maybe a Japanese Maple.

I agree on the castor plant.

Yes, definitely castor oil tree

The leaves look too small to be a castor bean. I'm with the others, I think it's a small maple tree they tried to kill. The roots may be pretty deep. Digging it out may be the answer.

Casrer leaves are larger than your hands. This looks like a maple tree.

Looks like ground elder to me

Looks Ike a maple to me. They tend to have lots of seeds they send out everywhere

it looks to me that it could either be a young maple or a very young sweetgum tree

Are there prickles on it? Could be Japanese Hop which is an invasive species. Although it is described as a vine, the leaves look identical.

I vote Sweet Gum (Gumball) trees. Invasive and drop pesky, prickly balls - everywhere. Just had 3 50+ footers cut down.

not the same leaf

Take leaf to your closet place that sells plants. They will know.

Guessing you're in a temperate climate, given the English ivy on the ground. They're woody plants, given their growth pattern and your note that they've been cut back before. My vote: sweet gum seedlings (Liquidambar styraciflua), American native tree. There must be one in the area as a seed source.

They aren't worth keeping. Grub them out if you can or cut them off at ground level and spray resprouts with Roundup (glyphosate) every 10 days until they no longer resprout.

When trying to identify a plant, look beyond the leaf itself. Many leaves look similar. Look also at growth patterns, bud placement and style, twig and bark color, and context in which it is growing. Many times, a plant will be the offspring of nearby plants, particularly in a situation like this. And, I also just noticed that the poster is from Georgia, where sweet gums grow wild everywhere. There is likely a sweet gum tree in the vicinity which provided a seed source for these unintended seedlings under the deck.

If you want to permanently get rid of these woody plants, I recommend Tordon. You might have to order it online if you local garden center doesn't carry it. It is a very thick liquid herbicide that is absorbed through the leaves and stems. Wear disposable gloves when applying. I found this was far superior to Roundup, easier to confine just where I wanted and killed woody plants to the root. It was the only thing that killed Buckthorn in my yard. Worked well on wild berry vines, too.

Look up Sweet Gum trees.

Looks like a granadilla vine.

look up marijuana

Its a tree (not marijuana.) I live in deep south Texas and I put roundup on what grew on our property. I know its a pain to have. It's like a noxious tree in that it's hard e get rid of it.

It looks like a Fatsia shrub. They are a shade loving plant, easy to grow and very hardy. I have an entire bed of them. The plant in your picture looks very "leggy," so you will need to cut it back to allow it to get full and lush if you decide to keep it.

Sweetgum; they have the five points of a sweetgum leaf, shiny leaves and the same color of green. They are not something you want to cultivate. Very invasive. Good luck.

If the leaves are delicate, it looks very much like an Aser (japanese maple) they come in a few different colours and will grow to tree size.