A berry or fruit, possibly from a plant associated with or eaten by harts (male red deer), or a plant bearing such berries.
From 'hart' (the male red deer) + 'berry.' This appears to be a dialectal or regional plant name, though the specific plant reference is uncertain.
Common names for plants are wonderfully mysterious—'hartberry' probably meant something specific to English country people centuries ago, but without written records of regional speech, the plant identification is now lost to time!
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