Fig 1.
Schematic showing process of ballistospore discharge.
Buller’s drop and the adaxial drop form via condensation of water on the spore surface and their coalescence causes a rapid shift in the center of mass of the spore that is responsible for the launch.
Fig 2.
Species of basidiomycete fungi (Class Agaricomycetes) examined in this study.
Fig 3.
ESEM images (A-C) and accompanying diagrams (D-F) showing droplet formation at 102% RH on the hilar appendix of a basidiospore dispersed from Russula aeruginea.
(A, D) Spore prior to droplet formation with hilar appendix appearing as rounded protruberance from the base of the spore. (B, E) Droplet beginning to form, and (C, F) continuing to expand. Scale = 2 μm.
Fig 4.
ESEM images of droplet (d) formation on the adaxial surface of basidiospores.
(A-C) Lactarius hygrophoroides, (D-F) Russula pulchra. The spores in this figure are viewed in profile with the hilar appendix protruding from the base and the adaxial surface above (arrows). (A-C) 103% RH; (D) 98% RH; (E,F) 102% RH. Scale = 5 μm.
Fig 5.
Dynamics of droplet growth, evaporation, and reformation on the surface of a basidiospore of Russula variata in response to changes in relative humidity controlled in the ESEM.
Fig 6.
Droplet formation on basidiospores of Suillus brevipes in the ESEM at 101% RH.
(A-D) Spores are orientated with adaxial surface facing away from surface of the specimen stub, allowing observation of droplets growing from this hygroscopic region of the spore. Note merger of droplets in second and third panels. Scale = 5 μm.
Fig 7.
Condensation of water on non-ballistosporic basidiospore from the puffball, Lycoperdon pyriforme.
(A) Spore prior to condensation of water at 100% RH and (B) with halo of water surrounding the spore at 101% RH. Scale = 2 μm.
Fig 8.
Overview of the mechanism of droplet formation on the surface of basidiospores.
(A-C) Condensation of water on the spore surface associated with spore discharge. Process of drop formation is driven by the presence of hygroscopic sugars on the spore surface in the two positions shown in gray in A. (D, E) Water evaporates from the surface of the airborne spore. (F) Condensation of water on the spore surface resumes under conditions of high atmospheric relative humidity. (G) Larger droplets of water formed by merger of spores carrying smaller droplets.