Actually, now I think back, my zucchini produced pretty big leaves. Maybe I should plant one next year in my perennial border.

Carol

Sun or shade?

I have a Ligularia dentata whose name in the trade is now 'Dark Beauty' - originally called something like Dunkelaubig (I know it wasn't spelled that way, but it was German and meant something like big honking beautiful dramatic dark green glossy leaves with maroon undersides). It does really well in shade; it tolerates some dryness, although the leaves are biggest in moister locations.

The most successful large-leaved perennial I have in sun is Crambe cordifolia, but the leaves are not much to look at, only partly because it's a magnet for every slug and insect pest on the planet - it's in the cabbage family; nuff said. When it flowers, though, it's quite a sight, and smells divine.

I do have a Darmera peltata, which is a great plant but only hardy to zone 6; I've also tried Astilboides tabularis, but have not had it survive for more than a few seasons. They all like more moisture than I can give them.

Then there's princess tree, which needs to be cut to the ground each year to prevent flowering and to produce those enormous leaves. I DO sometimes worry that if I get hit by a truck, mine will be left to grow and set seed, but since a) it's right next to the house and b) I look both ways before crossing the street, that's very unlikely to happen.

Can't wait to see what else people come up with.

Stooled catalpa, like the princess tree, will produce larger leaves, and there is a variety 'Aurea' with golden foliage. There are some hosta varieties with quite large leaves. There are ornamental rhubarbs in addition to the common edible variety.

Carol, are you sure that you can't try a Gunnera in a protected spot in your zone 7 garden? It might be worth a try.
Also, many of the arums have tropical looking foliage and many are very hardy, to zone 5 or even 4.

There's the Empress Wu Hosta that has huge leaves.

Claire

The Empress will get to be about 4 feet high and 7 feet wide in about 6 or 7 years. Here's a picture of two of them side by side in a garden in Rhode Island.

There are lots of Hosta that have leaves as large as this one. You could have one in gold (Key West), chartreuse (Sum and Substance) and/or Blue (Blue Angel or Elegans). These will all grow in some sun, but the leaves get bigger in full shade.

For non-hosta try Astilboides Tabularis or Rogersia.

Steve