The settling velocity of diaspores is a key parameter influencing dispersal ability in wind-dispersed plants but remains largely undocumented in bryophytes.
Zanatta et al. measured this parameter for nine species using a fall tower design combined with a high-speed camera and determine that, while settling velocity can be estimated by spore diameter in most of the cases, some spores show important departures from theoretical expectations. The authors investigate the potential causes of this divergence by taking specific variation in spore shape and surface roughness into account and suggest that this affects the balance between density and drag.
Florian Zanatta, Jairo Patiño, Frederic Lebeau, Mathieu Massinon, Kristofer Hylander, Myriam de Haan, Petra Ballings, Jerôme Degreef, Alain Vanderpoorten, 2016, 'Measuring spore settling velocity for an improved assessment of dispersal rates in mosses', Annals of Botany, vol. 118, no. 2, pp. 197-206 http://dx.doi.org/10.1093/aob/mcw092