An endophytic fungus called Guignardia endophyllicola was found in healthy leaves of many different plants in Japan and Thailand. The researchers discovered that this fungus can live inside a wide range of plants, including flowering plants, conifers, and ferns. They used DNA analysis to confirm that the fungus was the same across different plant species. This shows that Guignardia endophyllicola has a very extensive host range, meaning it can live inside many different types of plants.