Multi-scale electrical activity and signal propagation in the moss <i>Brachythecium rutabulum</i>

Abstract Plants and bryophytes display diverse forms of electrical activity, yet the organization of endogenous signals in mosses has received little attention. In this work, we present a long, uninterrupted macro-electrode recording of extracellular activity in Brachythecium rutabulum, providing the first centimetre-scale, multi-day characterization of its natural electrical behaviour. The moss exhibits a rich repertoire of electrical events, including components consistent with both physiological activity and slower drift-related processes: fast oscillatory spikes, slower rhythmic fluctuations and very slow depolarization waves. These patterns form a nested hierarchy of time scales, revealing that the moss operates simultaneously through rapid electrical events and slow integrative processes. Analysis across multiple electrode sites shows that electrical activity is not confined to local regions but propagates across the moss cushion with clearly ordered temporal delays. The recordings further reveal gradual baseline shifts, extended epochs of increased and decreased excitability and persistent temporal structure extending across long durations. Together, these findings suggest that moss cushions behave as spatially distributed excitable systems potentially capable of coordinating and integrating electrical signals across both space and time. This multi-layered organization supports the emerging view that moss can serve as a naturally evolved, energy-efficient living substrate for biohybrid sensing and unconventional computation.