Western Oregon is home to native Rhododendron species and is the center for cultivated Rhododendron production in the United States. These Rhododendron spp. are known to be infected with fungal endophytes. However, the community structure of these endophytes in native and cultivated Rhododendron is poorly understood. Our study targeted the foliar fungal endophyte communities of two native Rhododendron spp. and two non-native commercially cultivated Rhododendron varieties. Parallel culturedependent (fungal isolation and identification based on ITS sequencing) and cultureindependent sequencing approaches (metagenomic sequencing of the ITS region using 454 pyrosequencing) were employed, and results provided evidence of distinctly different community structure in each host species. Additionally, results indicated higher diversity among cultivated and nursery grown Rhododendron. This suggests that the close proximity of the nurseries sampled to the forest environment allows exposure to two distinct sources of endophyte infection. Together, our results show the importance of host identity and environment in structuring the associated endophyte communities. / Graduation date: 2013