Fig. 1.

Real and drag-minimizing spore shapes. (A) Minimal drag shapes for Re = 0.1 (darkest), 1, 10 (lightest). The arrow points in the direction of flight and spores are axisymmetric about this direction. (Left) Spore dimensions are given in physical units (assuming U₀ = 2.1 m·s⁻¹). (Right) All spores are scaled to have equal volumes. The near fore-aft symmetry is not imposed (20). Comparison of minimal-drag shapes with Astrocystis cepiformis (B), N. crassa (C), Pertusaria islandica (D) spores. (Scale bar: 10 μm.) Like surface ornamentations (Fig. 2 and Table 1), rounding of spore apices only mildly increases drag. [B, reproduced with permission from ref. 38 (copyright 1998, British Mycological Society); C, reprinted from Experimental Mycology Vol 14, Glass NL, Metzenberg RL, Raju NB, Homothallic Sordariaceae from nature: The absence of strains containing only the a mating type sequence, 16 pp, 2008, with permission from Elsevier; D, reproduced with permission from ref. 39 (copyright 2006, British Lichen Society).