In the Keywording panel, LR will show the ancestors of an applied keyword only if there is more than one keyword with the same name. For example, if the keyword hierarchy contains the keywords Applegate and Oregon > Applegate, then if you apply the latter to a photo, it will display as Applegate < Oregon:
The keyword Oregon > Medford isn't displayed as Medord < Oregon in the Keywording panel because there is only one keyword whose name is "Medford".
There is no way to change this behavior.
Thank you. That helps. Just to clarify, as long as I have the hierarchies established in the keyword list, I need only enter the name of the appropriate lower level? I don't need to enter all the levels. It seems that Lr includes the ancestors when one queries, even when they don't show in the panel. What happens on export? Does the full hierarchy then get into the keyword panel?
as long as I have the hierarchies established in the keyword list, I need only enter the name of the appropriate lower level?
That's right, as long as there's just one keyword with a given name. If there are multiple keywords with the same name, you'll have to use the ">" notation to disambiguate which one you're referring to.
What happens on export? Does the full hierarchy then get into the keyword panel?
When you export a photo, by default all the ancestor keywords will be included in the industry-standard keywords field of the exported photo. You can stop a keyword from being exported by right-clicking it in the Keyword List, selecting Edit Keyword Tag, and unchecking Include On Export.
Also, in the Export settings window, there is an option Write Keywords As Lightroom Hierarchy. If this is checked, fully qualified keywords (e.g. Oregon|Medford) will be written in a proprietary metadata field in the exported photo that only LR understands.