Hi,
Certain varieties of plants are heirloom. So it is not the type of plant, but the cultivars that have been around for a long time. Like with roses, there are heirloom ones which are called antique, but there are modern ones too. Old iris varieties are called Historic, not heirloom. Most plant groups have cut off dates to call something an heirloom. With roses, only groups that pre-date Hybrid Teas can be called antique. With irises, it is by time, 25 years I believe.
Anyway, there are way way too many to list! Was there certain reason you were asking? Like having plants that would of been grown when your house was built? If so, asking on the Cottage Garden and Perennials forums might help.
Remy

Thanks Remy. I was thinking along the lines of having plants that would have been there when my house was built. I didn't realize Heirloom status had to do with the cultivar, but that does make sense - thanks for educating me.

Last year I added more irises, rose shrubs, annabelle hydrangea, but wasn't sure what else. Peonies are nice, but they always topple over on me and the blooms are so short lived, but pretty nonetheless. Mine were always covered in ants as well, not sure if that is common.

Thanks again

You're welcome. Since you mention all plants that are loved by cottage gardeners, I really do recommend stopping by the Cottage Garden forum and posting about when your home was built. There are a lot of nice people who frequent there who would be more than happy to make suggestions from the original time period of your home. One oldie I think of immediately is hollyhocks, but as I said you'll get lots more suggestions over there.
I love my peonies, but they are not for everyone, so don't feel bad about not caring for them. Some people do get ants all over theirs, mine, not so much.
Remy