Towards a Better Understanding of Bird's-Nest Ferns in Hawai‘i

For many years, the native populations of bird's-nest ferns in Hawai‘i (known as ‘ēkaha) have been referred to as Asplenium nidus. Recent morphological studies on live plants and herbarium vouchers, along with literature review, reveal that the most appropriate name is A. musifolium, which is primarily known from Malesia and Southeast Asia. Furthermore, A. nidus was a horticultural introduction and is now naturalized. This work has also elucidated the need for critical study of bird’s-nest ferns in the Pacific, where several cryptic taxa may be present. Though these ferns do not possess many distinct characteristics, the shape of the midrib and the detail of the scales are diagnostic. We provide an overview of bird’s-nest fern diversity in Hawai‘i, a key to identify native and non-native taxa, recommendations for specimen preparation to improve visibility of diagnostic characters, and a discussion of future research directions.