Topological equivalence of stomata distribution patterns across vascular plants

Stomata are ancient anatomical structures on leaves that regulate the exchange of water vapor, oxygen, and carbon dioxide between plants and the atmosphere. Acting as valve-like gateways between internal tissues and the external environment, stomata may function as locally interacting networks. Theoretical and experimental evidence suggests that local interactions among neighboring stomata influence their function and spatial arrangement. From this perspective, analyzing stomatal distributions as networks may yield novel insights into observed spatial patterns and their generative mechanisms. We hypothesize that variability in stomatal arrangements arises from shared underlying rules, with observed diversity reflecting an epiphenomenon. To test this, we employed a multi-species, multi-site common garden approach to assess potential convergences in stomatal distribution. A network-based framework enabled us to reduce individual-level variability and analyze stomatal patterns as interacting systems. Our results show that, across species and environments, stomatal spatial configurations consistently align with a null model linking minimum spanning tree (MST) length to stomatal density. Although a variety of patterns were present, over-dispersed arrangements predominated. These findings suggest that physical constraints during stomatal development impose strong limits on the range of viable spatial configurations that can evolve.