DISPERSAL ECOLOGY OF VANCOUVERIA (BERBERIDACEAE)

All Vancouveria species are habitual myrmecochores of the Viola odorata type. The anatropous, bitegmic seed develops an unusual elaiosome in the form of a large, empty, folded and lobed sac of epidermal tissue. The thin-walled assimilating capsule dehisces along an oblique weak zone that probably represents the suture between two fused and unequal carpels. In V. hexandra the capsule opens early to expose immature assimilating seeds. Decurved pedicels, down-turned fruits, and weak funiculi produce tachyspory. The related Epimedium, Jeffersonia, and Plagiorhegma have appendaged seeds and other possible myrmecochorous features resembling those of Vancouveria. Myrmecochory was probably established in the early or middle Tertiary period. The Vancouveria-Epimedium complex indicates that enormous plant migrations may be accomplished by means of ants.