What does Boxing Day have to do with boxing?
1640s, American English adaptation of Low German kraanbere, from kraan "crane" (see crane (n.)) + Middle Low German bere "berry" (see berry). Perhaps so called from a resemblance between the plants' stamens and the beaks of cranes.
German and Dutch settlers in the New World apparently recognized the similarity between the European berries (Vaccinium oxycoccos) and the larger North American variety (V. macrocarpum) and transferred the name. In England, they were marshwhort or fenberries, but the North American berries, and the name, were brought over late 17c. The native Algonquian name for the plant is represented by West Abenaki popokwa.