I have created a rather large document and used several decorative glyphs within some headings. When creating the table of contens, these decorations are also used for the entries, which looks rather odd. Is there any way to prevent InDesign from using these glyphs or is it possible to provide alternative texts for the table of contents?
I've seen a wide variety of ways to handle TOCs that are supposed to differ from the corresponding entries in body text. Some of them are very clever. My go-to technique for what you describe is brutally simple. I style the decorative glyphs with a character style "Leafy Thingies" and, after I've updated my TOC, I select the whole TOC and do a Find/Change in Selection that finds all Leafy Thingies and replaces 'em with nothing.
(And then I write this up in the pasteboard, and when my client finds it two years later she writes me an email "Leafy Thingies? lol you crack me up")