Fig. 2.

Explosive spore discharge and development of the spore cloud from a Sphagnum fimbriatum capsule with a diameter of 2·15 mm containing approx. 213 000 spores (calculated from formula in Sundberg, 2000). The pictures show snapshots (25 frames s⁻¹) from video footage of: (A) the capsule on its shoot in a test tube in the frame before discharge; (B) the ‘spike’ at the moment of explosive spore discharge from the first frame; (C) the spore cloud after 0·24 s – note that the lowest part of the cloud has already started to settle while the upper parts are expanding upwards and sideways; (D) the centroid maximum at t_cen = 0·72 s, when as much of the cloud is settling as is rising, used for obtaining a proxy of h_cen, the maximum height of the average spore (in the ‘centre’ of the cloud); (E) peak height (h_peak) at t_peak = 2·44 s, when the cloud summit reaches its maximum (168 mm above the capsule top in this case) – all spores below the summit are now settling; (F) the cloud after 5·0 s, when all spores are descending and a large proportion has already settled while the remaining cloud is becoming difficult to observe because of a diminishing spore concentration. The vertical white scale bar in (A) represents 50 mm. (See also the video provided in Supplementary data, available online.)