one-berry
/ˈwʌnˌbɛri/noun
US. Any of several plants with single or apparently single berries: (a) the partridgeberry, Mitchella repens; (b) the Indian turnip or Jack-in-the-pulpit, Arisaema triphyllum; (c) the checkerberry, Gaultheria procumbens.
Origin
Mid 16th century (in an earlier sense). From one + berry.