On the Role of the Calyptra in Permitting Expansion of Capsules in the Moss Funaria

The presence of calyptrae was found necessary for young sporo- phytes of Funaria to develop the ability to form capsules. If the calyptrae were left in place, the sporophytes formed capsules. If the calyptrae were removed the frequency of capsule formation was a function of the length of the sporophytes at the beginning of the experiment. When sporophytes were shorter than 10 mm, capsule formation was postponed indefinitely if calyptrae were absent, and there was a strong tendency for intercalary growth to become indeterminate. Beyond a certain stage, determined by environmental and endogenous factors, 100% of naked sporophytes formed capsules. Setae thickened in the typical way when the sporophytes elongated without calyptrae. The absence of the calyptra had only minor effects on the timing and quality of capsule expansion, once the sporophyte was beyond its early de- velopment. Late in elongation, the absence of the calyptra seemed to promote earlier and more vigorous capsule expansion. But if the calyptra was removed just before the capsule expanded, the speed and vigor of expansion was not altered.