Are these dahlias?

[dilettante]

I've found these growing on my allotment in a bed that looked like it might have been used for flowers in the past. I'm not overly familar with dahlias, but I thought the leaves of these plants look a bit like those of dahlias. If not, what might they be? Can anyone help? They weren't there before Christmas, or if they were they might have been one of the things that had turned black with frost, or been sprayed by the allotment committee when they cleared the plot. They've grow under a (not as opaque as I'd thought) tarpaulin, which must have given them some frost protection.

Thanks in advance.

[veggiechicken]

Are they parsnips?

[Martin H]

No, they aren't Dahlias.

[roitelet]

I would be inclined to dig one up and see what's on the bottom.

[WendyC]

The first one looks like parsnip, and neither are dahlias.

[Gillykat]

Definitely not dahlias BUT.....definitely not nasties like couch grass, ground elder or knotweed either

[mothhawk]

I agree with VC. They look like parsnips. Dig one up and see what the root looks like.

[dilettante]

They are parsnips! Congratulations everybody, your prize is a good old fashioned air pie. I'm going to dig the rest up for the compost, they're a bit soggy and horrible.