Dispersal of a liverwort by a springtail
The small grayish creature on the head of the liverwort (Reboulia hemisphaerica) is a springtail (Bourletiella hortensis), an arthropod that resembles an insect. The liverwort is growing in a brick pavement crack. Fragile white filaments dangle below its head and adhere to the stem.
By breaking up habitats, cities interfere with dispersal of plants and animals. A small liverwort I observed growing in pavement cracks apparently engages arthropods (springtails) to disperse its spores.
This liverwort grows as a flat disk in cracks between brick pavers. After fertilization, the liverwort produces spore capsules embedded in its head elevated on a stalk up to 2 centimeters (3/4 of an inch) in height.
Springtail descending the stem of the liverwort shown above. It has picked up fragments of filaments which are stuck to its back. The springtail is minute––less than a millimeter in length.
Dangling below this head are fragile, sticky white filaments that break up and adhere to the stalk. I observed springtails climbing up and down stalks of the liverwort, which stuck fragments of the filaments onto fine hairs covering the springtails’ backs. The springtails inadvertently carried these filaments away as they clamored around the plants.
I hypothesized that spores from the head of the liverwort rain down on the sticky filaments and adhere to them. When the filaments cling to the springtail, the little arthropod becomes a transport vehicle for dispersal of liverwort spores.
Small arthropods may disperse spores of non-flowering plants like mosses and liverworts, but this service is difficult to assess. Dispersal of spores by visiting animals is more obvious in the case of stinkhorn fungi (Phallaceae). The bright red, odoriferous, spore-producing heads of these fungi attract large numbers of iridescent green flies that feed on a glistening discharge coating the fungal surface.
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