The Effect of the Calyptra on the Plane of Guard Cell Mother Cell Division in Funaria and Physcomitrium Capsules

The calyptra influences the plane of division in guard cellmother cells of Funaria and Physcomitrium. Normally, capsulesexpand while sheathed by the calyptra and the axes of the stomataare parallel to the axis of the capsule in both genera. Removalof the calyptra from an elongating sporophyte leads to setathickening prior to capsule expansion and an essentially randomorientation of stomata. If the calyptra is removed from a sporophyteof Funaria at the time the division of the guard cell mothercells is expected, guard cells of abnormal shape and undividedguard cell mother cells are found in unusually high frequency.