[6] The berry is glossy and, as with many blackberries, appears black on the plant, but turns a deep, dark purple when frozen and thawed.

Waldo made the initial cross in 1945, selected it as OSC 928 in 1948 in Corvallis, and tested it in Marion County and elsewhere in the Willamette Valley.

[8] Oregon produces 90% of the US grown, frozen blackberries found in US grocery stores,[9] with Marion County and the Willamette Valley collectively accounting for most of that production.

[7][9] The marionberry is well-adapted to the mild, maritime western Oregon climate, with its frequent rains and warm summers.

These plants are long living (15 to 20 years) perennials, hardy and cold tolerant, easy to grow, and productive spreaders.

[4] Marionberries – as fresh or frozen fruit or in various products, such as jam, syrup or ice cream – are widely consumed and prized by visitors to the Willamette Valley as a souvenir.