In contrast to the extensively researched modeling of plant architecture, the modeling of plant organs largely remains an open problem. In this paper, we propose a method for modeling lobed leaves. This method extends the concept of sweeps to branched skeletons. The input of the model is a 2D leaf silhouette, which can be defined interactively or derived from a scanned leaf image. The algorithm computes the skeleton (medial axis) of the leaf and approximates it using spline curves interconnected into a branching structure (sticky splines). The leaf surface is then constructed by sweeping a generating curve along these splines. The orientation of the generating curve is adjusted to properly capture the shape of the leaf blade near the extremities and branching points of the skeleton, and to avoid self-intersections of the surface. The leaf model can be interactively modified by editing the shape of the silhouette and the skeleton. It can be further manipulated in 3D using functions that control turning, bending, and twisting of each lobe.