Mosses were among the first plants to colonize land over 400 million years ago, but they never really left the water behind. Unlike seed plants, mosses (as well as ferns and liverworts) don’t enclose their sperm in pollen but release it directly. Since their unprotected sperm is vulnerable to drying out, these plants can only reproduce if there’s a watery film through which the sperm can swim. However, recent research has started to uncover a more complicated story behind the sex life of mosses. Mounting evidence suggests that mosses recruit micro-arthropods like springtails and mites to carry their sperm in the same way that flowering plants attract and reward insect pollinators.
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