Rubus × 'APF-12' (marketed as 'Prime-Jim') is an erect, thorny blackberry cultivar historically celebrated as one of the world's first commercial primocane-fruiting blackberries. Released in 2004 by the University of Arkansas, it was developed through a controlled cross between the thornless, erect cultivar 'Arapaho' (the female parent) and the unreleased, thorny breeding selection 'Ark. 830' (the male parent). This precise genetic pairing aimed to introgress a rare, recessive double-cropping trait—originally traced back to the wild Virginian selection 'Hillquist'—into an upright agronomic architecture. 'Arapaho' provided the necessary structural stability and genes for high fruit quality, while 'Ark. 830' carried the vital primocane-fruiting genetics, resulting in a hybrid capable of flowering and fruiting on first-year canes (primocanes) in late summer, in addition to the traditional early-summer crop on second-year canes (floricanes).

The fruit of 'Prime-Jim' is medium-to-large, elongated-ovate in shape, and develops a glossy black exterior when fully mature. Because it was an inaugural release for this fruiting architecture, the berries retain a prominent wild-type tartness and are highly thorny, characteristics inherited from its paternal line, making it highly favored for home gardens and local processing rather than long-distance shipping markets. It serves as a foundational benchmark for studying how dual-season fruiting genetics impact the chemical composition and harvest windows of domesticated small fruits.