Fern Reproduction: Part 2

It's difficult to choose a blip from a great weekend away, especially as others who were there will probably use similar ones, so I have returned to this subject in contrast. The original fern frond has begun to dry out a little. Compare this blip with July 5th.

On each pinnule, the several indusia have shrivelled to expose the many ripe sporangia. Inside these are the hundreds of spores which, when the sporangium ruptures, will be carried away to some waterlogged ground, on the wind, to grow into a minute prothallus, bearing the sexual apparatus necessary to create the new fern frond.

The sporangium wall breaks open due to unequal drying of the cell walls from outside to inside. This causes tension and an eventual rolling back of a weak strip, a little like the lid on a sardine can.

Ferns are able to grow extra height, off the wet ground, as the fronds have a mechanism to transport water upwards, unlike mosses. The material used doubles as a support structure so allowing for greater complexity of form, hence improving their chances in the competition for light, and spreading dry spores further afield.