The document summarizes two mechanisms of spore dispersal in plants. The pop gun mechanism involves the shrinking sporangia creating air pressure that forcibly ejects the operculum and shoots the spores into the air, as seen in Sphagnum. The censor or salt mechanism uses an epiphragm closing the capsule mouth, with tiny gaps between the attached peristome teeth allowing the spores to be ejected, as seen in Polytrichum.

1. DISPERSAL
OF
DIASPORES

17. POP GUN MECHANISM : In this mechanism as the
sporangia dries out , it shrinks in diameter and the
columella collapse and is replaced by air space.
The shrinking capsule place the air under
considerable pressure. This pressure against
operculum force it to be thrown off violently,
unzipping the annulus ring and the spores are shot
in the air with a sound which can be heard at a
distance . For example- SPHAGNUM.

19. CENSOR OR SALT MECHANISM: IN this mechanism the
apex of the columella is expanded to form epiphragm that
nearly closes the capsule mouth . The margins of the
epiphragm are attached to the inner tips of peristome teeth
that arched over the epiphagm . Between each of the teeth
and point of attachment of the margins of the epiphragm
are tiny gaps and through the holes that the spores are
ejected . For example : POLYTRICHUM.