Vegetative spreading ofOxalis pes-caprae (Oxalidaceae)

Abstract

The underground movement ofOxalis pes-caprae L. is a combination of shoot elongation and root contraction. Its function is the dispersal of renewal bulbs located in the axils of the scale leaves. At the beginning of root contraction the bulb leaves become detached from the bulb bottom and remain at their initial position. Bulb bottom and contractile root form a turnip-shaped unit. Its proximal end becomes displaced by shortening of the root. While contracting, the root develops a pulling force, which is quantified by using the lifting method. Connection between the overground shoot and the contractile root is maintained by a few short basal internodes of the new shoot, which elongate to form a thin underground “thread”. Elongation of the thread and shortening of the root reach 20–30cm and obviously occur synchronously, whereby the thread remains taut during movement. Along the thread several lateral buds emerge. These develop into renewal bulbs usually reaching the size of the mother bulb.