Fig. 3

Comparison of two models of viscous drag for projectiles launched from five fungal species whose initial launch speeds are characterized by Reynolds numbers (Re) ranging from 0.3 to 167 (Fischer et al. 2010b). For each species, maximum discharge distances and initial launch speeds were directly measured, the latter by means of ultra high-speed videography. In each case, the launch speed required to obtain the observed discharge distance and the predicted discharge distance based on the observed launch speed were calculated using two drag models: Stokes’ Law (here labelled “Our Model”) and a more complex semi-empirical model (“White”) that is representative of drag models typically used to model viscous drag for Re> 1. For low Re, Armillaria and Gymnosporangium, both models accurately model the drag. For larger Re, Stokes’ Law continues to successfully model the drag. The White model, however, consistently overestimates the drag requiring either extremely large launch speeds (210 ms⁻¹ for Pilobolus) or severely underestimating the discharge distance (0.7m vs. the observed 2.5 m for Pilobolus). Supplied by Mark Fischer.