Notes on Sparganium coreanum (Typhaceae) rediscovered on the Korean Peninsula

Sparganium coreanum, a barely recognized species in Korea, was rediscovered during a field survey by the authors, who conducted a re-examination of specimens deposited in the Herbarium of the Korea National Arboretum (KH). This species was described initially by H. $L{\acute{e}}veill{\acute{e}}$ from a specimen collected by F. Taquet from Jeju-do (Taquet 2150). Subsequently, however, it was overlooked and unrecognized among South Korean flora. Several populations of S. coreanum were found in the southern part of the Korean Peninsula and on Jeju-do, although it has long been recognized as S. erectum owing to certain vegetative morphological characteristics shared between the two species, such as robust stems, a similar plant height, and globose rhizomes. However, it is distinct from S. erectum by the number of female heads on the lowest inflorescence branch and the size and shape of the fruit. In this study, we provide a detailed description, illustrations, and photographs with a revised taxonomic key for identification of Sparganium species in Korea.