A forest of a south beach species (Fuscospora cliffortioides). The root-associated fungi of the plant constitute a symbiont-to-symbiont co-occurrence network, which are divided into two clear compartments. As a result, host plant population is divided into two clusters representing distinctive community structures of root-associated fungi (i.e., ‘rhizotypes’). The topology of the symbiont–symbiont network further suggests the presence of ‘hub’ fungal species, which are expected to control the ‘alternative stable states’ of symbiont communities within host root systems. Image courtesy of Hirokazu Toju.