A test of the air-seeding hypothesis using sphagnum hyalocysts.

"Air-seeding" is a proposed mechanism for the initiation of water stress embolism in dead plant cells. During air-seeding, external air is drawn into the lumen of a dead plant cell through a pore or crack in the cell wall. The resulting bubble may expand to fill the lumen, thus embolizing the cell. The data presented confirm that Sphagnum hyalocysts can embolize by air-seeding when the pressure difference across the air-water meniscus is given by DeltaP = 0.3/D (derived from the capillary equation), where DeltaP is the pressure difference across the meniscus (megapascal), and D is the diameter (micrometer) of the pore through which the air bubble enters.