mulching info

We are in the middle of a terrible drought here in the mtns. of NC. I live in a county that ordinarily gets more rain than anywhere else in the lower 48 states except for Olympia, Washington. So we are desperately watering.
I have added some mulch and will add more tomorrow. However, since I write a gardening column, I would like to know what plants/shrubs/trees that you CAN'T mulch.
Does anyone know of a list of these plants? It seems like I heard you could mulch dogwoods but could not let the mulch touch up against the bark. Is that true?

Bearded iris (www.bachmans.com says not to b/c the borer's more active on mulched plants).

Yeah, but I need a list of all plants that can't be mulched, at least, not right up to contact with the trunk or main stem

I have surely read before, in general tree trunks should NOT have the mulch piled up on them. Can't help otherwise.

thank you, Sally.

Same with roses, don't mulch up to the trunk. I think that's because the mulch can cause moisture rot and fungus disease.

I don't think I've ever read of a plant that should not be mulched... maybe a cactus?

It has more to do with the type of mulch and how close to the base or trunk you place the mulch
A few plants are extremely sensitive to damage by high soil temperatures, therefore maybe straw would be better than bark.

That surprised me with roses. OOPSY, gotta get down to the rose bed.