FERNS and FERN ALLIES
Wads of grey-green spores trail from sporangiophores of the strobilus of the mature horsetail Equisetum arvense.
The wads of spores begin enlarge their volume in tens of seconds, when drying.
The microscope elucidates what happens with spores during their drying: each spore posses four elastic hapters which erect quickly when dried and catapult the spore out from the strobilus. Photomicrograph, prim. magn. 400–800×.
An axial view into a bunch of fern fronds.
Rows of sori are placed on the underside of fertile leaflets.
The mature reddish-colored sori open to expose membranous worm-like sporangia. The sporangia are filled with spores and equipped with an elastic annulus.
The microscope elucidates what happens with sporangium during its drying: the annulus quickly erects like a spring, the membrane bursts and throws the spores out. Prim. mag. 200–400×