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How do horsetail sporangia release their spores?
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Equisetopsida
Giant horsetail of Europe (Equisetum telmateia).
Horsetail (Equisetum) sporangia release their spores through a longitudinal slit on their inner side.1
The dissemination of these spores is facilitated by four ribbon-like appendages known as elaters, which are formed from the outermost wall layer of the spore. These elaters are highly sensitive to moisture; they coil and uncoil in response to changes in humidity, which helps to disperse the spores from the sporangia.21