Wing loading regulates descent time in <i>Liriodendron</i>  ×  <i>sino-americanum</i> samaras: bilateral symmetry and allometric scaling

Wind dispersal of Liriodendron × sino-americanum samaras depends critically on functional traits like mass, projected area, symmetry, and wing loading (mass-to-area ratio). Although wing loading’s role has been recognized, its scaling with size/symmetry and symmetry’s impact on descent remain unclear. Using 630 samaras, we quantified traits (mass, projected area, bilateral symmetry of 2-D projection) and measured descent time in free-fall experiments. Variation was highest in fresh mass (CV = 30.9%), followed by bilateral symmetry (CV = 29.9%) and projected area (CV = 20.3%), but lowest in descent time (CV = 12.6%). Wing loading was detected as the primary determinant of descent time, showing a strong negative correlation with mean decent time (r = −0.697). Mean descent time decreased with increasing mass and, weakly, with projected area. Mass increased disproportionately faster than area (scaling exponent = 0.643 < 1), diminishing area’s buffering effect on descent time reduction. Thus, the disproportionate increase in mass relative to area resulted in higher wing loading and consequently accelerated descent. Bilateral symmetry minimally directly affected descent time but conferred stability via autorotation. This highlights a trade-off between dispersal distance (reduced by faster descent) and seed reserves (enhancing establishment).