1:36 PM PT -- Sally's rep tells us her head gash was too severe for stitches so she's in surgery right now.

Sally Kirkland was rushed to a hospital by ambulance Wednesday afternoon after taking a terrible fall during a radio appearance ... TMZ has learned.

Sally, a veteran movie star who has been nominated for a Best Actress Oscar, was doing John Fugelsang's show on SiriusXM. We're told she fell on her knee and face and suffered serious lacerations. An ambulance came and took her to a nearby hospital.

Doctors were doing triage at the time this story was posted. We're told she'll require a number of stitches but is expected to fully recover.