Extended Data Fig. 1 - SVR visualization of the wake of 10 fixed dandelion seeds - The flow speed is half of the terminal velocity of the seed. Each image was obtained using long-exposure photography.

Extended Data Fig. 2 - SVR visualization of the wake of 10 freely flying dandelion seeds - a–j, Each image corresponds to a snapshot from a video of the flight of the dandelions in the wind tunnel. The images show the seeds as they pass through the laser sheet, and the SVR may be difficult to identify in some panels because of the orientation of the laser sheet with respect to the axis of the SVR.

Extended Data Fig. 3 - The breakdown in symmetry in the SVR of dandelion seeds - a, b, At low speeds, the SVR is axisymmetric. a, Contrast-enhanced image. b, Original image. c, d, At higher speeds, this symmetry is lost. c, Contrast-enhanced image. d, Original image. a–d, Experiments were repeated independently on n = 10 biological samples, with similar results. e, f, The axisymmetry of SVR at low Re (e) breaks down at higher Re (f).

Extended Data Fig. 4 - Images of porous disks showing the resolution of the technique for disks of various porosities - a, b, Impervious disk. c–f, A disk with 33% porosity. g, h, A disk with 55% porosity. i, j, A disk with 75% porosity. k–p, A disk with 89% porosity.

Extended Data Fig. 5 - Steady and unsteady wake behind porous disks and pappi - Video snapshots are shown. a–d, The flow visualization behind a solid disk, with a steady wake (a) and an unsteady wake at three time points within one period of vortex shedding (b–d). e–h, The flow around a porous disk (ε=0.75) with a steady wake (e) and an unsteady wake at three time points within one period of vortex shedding (f–h). i–l, The wake behind a dandelion sample with a steady SVR (i) and at three time points within one period of vortex shedding (j–l)

Extended Data Fig. 8 - The flow past a porous disk using direct numerical simulations and boundary integral methods - a–c, The axial velocity uz/U (a), pressure p/ρU² (b) and streamlines (c), showing the presence of an SVR with upstream and downstream stagnation points z_su and z_sd, respectively. d, The reduction in the drag force on filaments within an array moving at slow speeds calculated using a boundary integral method. The force D_i on the ith filament of a rectangular pappus, divided by the drag force for an isolated filament D_0.