el·a·ter 
(ĕlə-tər)
(ĕlə-tər)n.
1. An elaterid beetle.
2. Botany A tiny elongated structure that forces the dispersal of spores by the absorption of moisture. It is either a band attached to the spore, as in horsetails, or a filament occurring among the spores, as in liverworts.
[Greek elatēr, driver, from elaunein, to drive.]