"A boysenberry /ˈbɔɪzənbɛri/ is a cross between a European Raspberry (Rubus idaeus), a Common Blackberry (Rubus fruticosus), an American Dewberry (Rubus aboriginum) and a Loganberry (Rubus × loganobaccus).[2]
It is a large 8.0-gram (0.28 oz) aggregate fruit, with large seeds and a deep maroon color,[3] which changes to the typical boysenberry color when the fruit is cooked and made into jam and pie." -Wikipedia