Introduction

Traditionally the Genus Racomitrium Brid. was a large genus of the family Grimmiaceae, and about 80 species are known around the world until the mid-1990s (Bendarek-Ochyra, 2006). Its species are medium size to large plants and vary in color from yellowish to brownish green growing in tufts or extensive mats and are commonly found from arctic to tropical zones of both hemispheres. Racomitrium mosses mainly live in dry environments such as sunny rocks and sandy soil. But some species are known to be sensitive to climate change (Osaki and Nakatsubo, 2021) and are used in horticulture and landscape fields. Although the genus is readily distinguishable, it is known that the species classification of the genus is as one of the most difficult among mosses (FNA Editorial Committee, 2007). The re-establishment of this genus is being discussed because of the taxonomic problems existing in the complexes of specimens, in current. Of these, 18 species had been reported in the Korean genus, and 6 species, especially, were first discovered on the Korean Peninsula in the early 1900s and reported as new species by foreign scholars (Cardot, 1907, 1908; Lee and Choi, 2012).

Recently as the moss industry has grown in Korea, the research on mosses about cultivation, extracts, etc. has also increased (Nam et al., 2011; Suh et al., 2010; Yim et al., 2013; Yoo et al., 2024, 2025). The genus Racomitrium, a resource plant for indoor landscaping and packaging, has recently attracted attention as a resource plant with excellent carbon reduction capabilities, and response capabilities to the climate (Tamura et al., 2019). As interest in Racomitrium mosses with high potential commercial value, such as moss frames and humidifiers, has increased, a new cultivar called ‘Carbon Flower Moss’ has developed in Korea (Jung, 2024). There is also a growing demand for information on not only the morphological characteristics of native Racomitrium mosses but also environmental factors for cultivation. The aim was to provide detailed information on the environmental elements and morphological characteristics of native Racomitrium mosses in Korea. Specifically, this study was to (1) characterize habitat preferences (altitude, topography, light, moisture, substrata) for each species, and (2) discuss implications for cultivation and habitat conservation.

Materials and Method

This study on the genus Racomitrium was primarily based on the examination of herbarium specimens. Living samples of four species were also collected from various locations in Korea, including Mt. Gamaksan in Paju Mt. Magamsan in Yeoju, Mt. Gayasan in Yesan and Mt. Hallasan in Jeju. The identification of bryophytes was based on domestic and international literature such as Illustrated Flora and Fauna of Korea. Vol. 24 (Choe, 1980), Spore Plant of Joseon 9 (Hwang, 1991), Moss Flora of China Vol. 1 (Chien et al., 1999), Moss Flora of China Vol. 2 (Li et al., 2001), Moss Flora of China Vol. 3 (Chien et al., 2003), Moss Flora of China, Vol. 6 (Wu et al., 2002), Illustrated Moss Flora of Japan (Noguchi, 1988), The Flora of North America bryophyte Vol. 27 (FNA Editorial Committee, 2007), Mosses and Liverworts of Britain and Ireland: A Field Guide (Atherton, 2010), and Websites (NBDC, 2024; WFOC, 2024). The Biodiversity of the Korean Peninsula for the adoption of scientific names was followed (NIBR, 2024). In the course of this study approximately 63 dried herbarium specimens were examined from the following 4 institutional herbarium in Korea; NIBR, NMR, and Japan; TNS, HIRO. The description of the genus Racomitrium was accompanied by relevant additional material in which taxonomy and nomenclature as well as 16 species geographical distribution are discussed. In ecological study approximately 3,515 labels (included 2,248 labels of HIRO) of herbarium specimens were examined from the following 97 institutional herbarium including open data on website (CNABH, 2024); ACAD, AK, ALA, ASU, BALT, BRIT, BRU, BRY, BUT, CANB, CAS, CGCC, CHSC, CINC, CLM, CMN, CNABH, COLO, CSCN, DAV, DUKE, ELON, EVE, EWU, F, FH, FLAS, GB, HIRO, HPSU, ILL, ILLS, ISC, KE, KSP, LD, LEDLIE, LSU, MAINE, MCTC, MDKY, MICH, MIN, MNHN, MO, MONTU, MSC, MT, MU, MW, NCU, NDA, NEB, NHA, NHMUK, NMCR, NY, NYS, OHN, OS, OSA, OSC, PH, PTBG, RM, S, SFV, SJFM, SJSU, SNM, SQB, SRP, SYKO, TENN, TOYA, TRH, TROY, UARK, UBC, UC, UConn, UCSC, UME, UNAF, UNLV, UNM, US, USF, USU, VPI, VT, WIS, WS, WTU, WVA, WWB, YPM. The data matrix for distributions and habitats was standardized. Cross-tabulation processed using SPSS Statistics (Statistical Package for the Social Sciences, version 22, IBM) was performed by organizing topography, light, moisture, and substrata to study species-specific habitats in the genus Racomitrium. And, according to the analysis criteria of Bakalin (2010), which classified bryophytes into climatic zones, 16 species of the genus Racomitrium in Korea were analyzed into 9 climatic zones.

Results

A history of the Genus Racomitrium

The genus Racomitrium Brid. was established in 1818 by Samuel Elisée Bridel-Brideri (Bridel, 1819) as large genus about 80 species in the world traditionally (Bedenarek-Ochyra, 2006) and are growing as tufts or extensive mats and from Antarctica to temperate zones (FNA Editorial Committee, 2007). Mosses in this genus were traditionally characterized as medium to large, coarse, and rigid. Their laminal cells have thick, strongly sinuose to nodulose cell walls, papillose and the leaves often have hyaline hair-points (FNA Editorial Committee, 2007).

1) Etymology

The name Racomitrium is derived from the Greek words ‘rhakos’ (rag or remnant) and ‘mitra’ (turban), referring to the calyptra―a protective cap over the moss capsule―which is frazzled or lobed at its base (Bridel, 1819; FNA Editorial Committee, 2007). The genus Racomitrium Brid. was used to spell as both ‘Racomitrium’ and ‘Rhacomitrium’ for a while. Many researchers have used the original spelling of ‘Racomitrium’, but others used an orthographic variant of this name, Rhacomitrium’, used for the first time by Lorentz (Lorentz, 1864; Bednarek-Ochyra, 2006). Racomitrium was considered the correct and cleared the name for the genus after 1898 (Bednarek-Ochyra, 2014; Paris, 1898). But many specimens still are labelled as ‘Rhacomitrium’ in several Herbarium.

2) Taxonomic History

Historically, Racomitrium was a large genus with about 80 species. The identification of the genus itself was relatively straightforward due to its distinct characteristics, but species classification was considered one of the most difficult among mosses (FNA Editorial Committee, 2007). Nowadays Racomitrium was revised and split into five genera Codriophorus, Niphotrichum, Bucklandiella, Dilutineuron, Racomitrium (Bednarek-Ochyra, 1995, 2000, 2003; Bednarek-Ochyra et al., 2015; Bednarek-Ochyra and Ochra, 2017; Erzberger et al., 2016) (Table 1).

3) History in Korea

The study of the genus Racomitrium in Korea began in the early 1900s with collections by Urbain Jean Faurie and these specimens were sent to the bryologist Jules Cardot, who accepted six species of Racomitrium from Korea (Cardot, 1907, 1908; Lee and Choi, 2012). And in the beginning of 20 century Korea bryophytes studies were by Japanese researchers and most of the collections were being stored in Kyoto University herbarium and TNS herbarium (Lee and Choi, 2012). Korean bryophyte research was later advanced by scientists like Hong, WonShik in the 1960s and Choe, DuMun in the 1970s and 1980s (Lee and Choi, 2012). Despite these efforts, the habitats and distribution of many Racomitrium species in Korea remain obscure due to the small number of bryophyte researchers.

In North Korea Racomitrium were reported eight species as sand moss (Hwang, 1991). In South Korea, a total of six species of Racomitrium were reported in the ‘Illustrated Flora and Fauna of Korea. Vol. 24. Musci, Hepaticae’ published by Choe, DuMun in 1980. 16 species of Racomitrium were reported in New List of Mosses in Korea published by the National Arboretum (Park and Choi, 2007), 15 species of Racomitrium were reported in National Species list of Korea published by NIBR (Lee et al., 2011; NIBR, 2019) and 18 species of Racomitrium were reported in National Species list of Korea (NIBR, 2022, 2023, 2024) and by Kim et al. (2020) (Table 2).

Racomitrium fasciculare var. orietale Cardot which was named by Cardot in 1908 and collected from Mt. Wonsan and Mt. Hallasan was not included in the list of the North Korea and South Korea, because it was treated as synonyms of Racomitrium fasiculare (Bednarek-Ochyra, 2006).

Ecology

Through a literature study, the distribution areas of a total of 18 species of the genus Racomitrium were identified, and it was confirmed that the type specimens of a total of 6 species originated from the Korean Peninsula (Cardot, 1907, 1908; Choe, 1980; Hwang, 1991; Lee at el., 2011; NIBR, 2019) (Appendix 2). Through a field survey, it was confirmed that Niphotrichum japonicum inhabited rocks in sunny valleys, and that it contacted Bucklandiella heterosticha and Codriophours carinatus inhabited rock surfaces in wetlands. The ecological analysis of the genus Racomitrium was based on the collect site information on 3,515 specimens of 17 species. Codriophorus varius was excluded because it seemed to be misidentification. The distribution and altitude of the genus Racomitrium were organized, and the climatic distribution characteristics by Bakalin’s standard were identified (Bakalin, 2010; Bum et al., 2020).

Analysis of habitat preferences by species

In ecological study, approximately 3,515 labels of herbarium specimens were examined from the following 97 institutional herbarium. The information on herbarium labels which often contained insufficient or ambiguous information was excluded. Through this, the information on the collect site (country, state), altitude, topography, light, moisture, and substrata were collected and summarized into a smaller number of factors to make the data matrix. SPSS cross-tabulation was conducted to find out the association with species-specific habitats (altitude, topography, light, moisture, and substrata).

1) Altitude

Overall, the preference for altitude showed high frequency in the order of ‘1,000-1,999 m’ (939), ‘100-999 m’ (870), and ‘2,000-2,999 m’ (650). Dilutineuron canaliculatum and N. japonicum showed the highest frequency at ‘100-999 m’, Bucklandiella laeta and Codriophorus fascicularis at ‘1,000- 1,999 m’, and Bucklandiella sudetica and R. lanuginosum at ‘2,000-2,999 m’, respectively. In particular, N. japonicum was found to commonly inhabit lowlands compared to other species (Appendix 3). The results are shown in Table 3.

2) Topography

In the topography results, among the 10 types (cave, forest, mountain, valley, meadow, lake, river, wetland, ricefield, road), ‘meadow’ (53), ‘river’ (45), ‘forest’ (42), the topography preference was shown in that order (Table 4). N. japonicum showed the most preference for meadow. D. canaliculatum showed a preference for forest and river. B. sudetica, C. carinatus, D. canaliculatum, Niphotrichum barbuloides and N. japonicum were shown to inhabit various habitats (Table 4).

3) Light

In light, it was organized into shade, partial shade, and sun. Regarding light, it appeared in the order of sunny places (176), partial shade (58), and shade (20). Therefore, it appeared that most species preferred sunny places (176) (Table 5).

4) Moisture

In moisture, it was organized into dry, meso, moist, submerged, and wet in five stages, most of the species were found to inhabit a variety of moisture conditions from dry to wet places. However, it appeared to prefer dry environments the most. Dry (140), Wet (92), moist (60), meso (58), and submerged (1) were found to prefer dry places in order (Table 6).

5) Substrata

Substrata was organized into a total of 12 types, and as a result, Rock (1,046), Boulder (451), and Soil (383) were found. Codriophorus acicularis mostly was found to inhabit rock, and boulder. Bucklandiella laeta, B. sudetica,C. carinatus, C. fascicularis, D. canaliculatum and N. barbuloides were found to inhabit a variety of substrata, but preferred rocks. N. japonicum was found to favor soil relative to other species (Table 7).

Climatic distribution of species

In climatic distribution, it was organized into 9 types. It appeared Boreal Temperate (7 species), Temperate-Subtropicial (2 species), Multi zone (5 species), and Temperate (2 species) (Table 8).

Discussion

Interest in bryophytes is increasing that they are included in the national strategy, such as using moss for urban carbon neutrality. In the case of N. japonicum, which grows well in the domestic environment, it is known that a variety has been developed, and a variety protection application is in progress, and a farm specializing in the cultivation of the genus Racomitrium (Jung, 2024). While the commercial potential of these bryophytes is evident, the fundamental research required to support their large-scale cultivation and conservation has been insufficient. This study addressed this critical gap by providing detailed of the genus Racomitrium in Korea, drawing upon existing domestic and international research and a vast collection of herbarium specimens.

The analysis of the specimen data showed significant differences in habitat preferences among the various species (Appendix 1, 3). The distribution of species showed a clear preference for specific altitudinal ranges D. canaliculatum and N. japonicum were most frequently found at lower elevations, between 100 and 999 meters, B. laeta and C. fasciculare showed the highest frequency in the mid-altitudinal range of 1,000 to 1,999 meters, B. sudetica and R. lanuginosum were found predominantly at higher altitudes, ranging from 2,000 to 2,999 meters (Table 3, Appendix 3). In Habitat analysis N. japonicum was found to be a common inhabitant of lowlands and demonstrated a strong preference for meadows. D. canaliculatum showed a clear preference for forest and river habitats. The study also found that several species, including B. sudetica, C. carinatus, D. canaliculatum, N. barbuloides, and N. japonicum, could inhabit a wide variety of habitats (Table 4). Most of the species in the study were found to prefer sunny places (Table 5). Furthermore, most species appeared to inhabit e wide range of humidity conditions, from dry to wet (Table 6). The type of substrata also played a significant role in species distribution. C. acicularis was found to inhabit rocks and boulders almost exclusively. Other species, such as B. laeta, B. sudetica, C. carinatus, C. fasciculare, D. canaliculatum, and N. barbuloides, were confirmed to inhabit various substrata but generally showed a strong preference for rocks. N. japonicum, in contrast to other species, appeared to favor soil as a substrata (Table 7). Bryophyte identification based solely on specimen photographs available online is challenging. Consequently, online information contains misidentified specimens, making accurate habitat data difficult. Notably, according to Moss Flora of China Vol. 3. (Chien et al., 2003) and Flora of North America Vol. 27. (FNA Editorial Committee, 2007), many East Asian specimens previously identified as N. canescens were in fact N. japonicum. This confusion stems from mixed-errors in type specimens (Bednarek-Ochyra, 2006), resulting in Noguchi’s (1988) morphological description of N. canescens in Moss flora of Japan (Noguchi, 1988) incorporating the characteristics of N. japonicum, thereby causing frequent misidentifications between these two species. Taxonomic revisions conducted by Japanese Herbarium (TNS and HIRO) and Polish researchers have involved the re-identification of misclassified the genus of Racomitrium specimens. In this study, to accurate the data of the habitat, identification of N. canescens and N. japonicum among collected specimens in Korea was based on Moss Flora of China Vol. 3. (Chien et al., 2003) and Flora of North America Vol. 27. (FNA Editorial Committee, 2007) and habitat data were collected by borrowing specimens re-identified of Racomitrium species from TNS and HIRO as possible as. To enhance the reliability of habitat information, systematic organization through future direct field collections in Korea and re-examination of herbarium specimens from both domestic and international collections are essential.

Racomitrium species showed distinct patterns in their climatological distribution across East Asia (Appendix 1, 2). This information suggested the varying adaptability of these species to different climatic conditions. The species of Racomitriuim were organized under the Boreal Temperate climate zone are typically found in cooler regions, often at higher latitudes or altitudes. Their habitat information, which frequently lists locations like mountains and high-altitude areas, aligns with this classification. This study demonstrated that while some species had a more specialized distribution, some species like B. heterosticha, B. sudetica, C. facicularis, C. mollis, and R. lanuginosum had a high degree of allowing them to occupy diverse ecological niches across East Asia (Table 8).

During the study, specimens of Bucklandiella microcarpos, Codriophorus mollis, and C. varius could not be confirmed. It is suggested that B. microcarpos is a rare species in East Asia, while C. mollis is either rare globally or has been insufficiently studied (Hwang, 1991; Kim et al., 2020; NIBR, 2019, 2022, 2023, 2024). The study concluded that C. varius was likely a misidentification in previous Korean literature (Kim et al., 2020; NIBR, 2019, 2022, 2023, 2024), as it was known to be endemic to western North America (Bednarek-Ochyra, 2006). Consequently, C. varius was excluded from this study, despite being listed in the National Species List of Korea.

The morphological characteristics of the reviewed the genus Racomitrium, such as the hyaline hair-point at the leaf apex and looks like a frosty appearance, making it higher valued for landscaping. N. japonicum, commercially known as sand moss, is particularly popular due to its drought- resistant properties (Tamura et al., 2019) and its ability to thrive in a variety of habitats, which simplifies cultivation. While the research into mass propagation for commercialization is ongoing, there is a noted lack of fundamental research on protecting native habitats and genetic resources. This is attributed to a shortage of researchers dedicated to basic bryophyte studies. While research into mass propagation for commercialization is ongoing, there is a noted lack of fundamental research on protecting native habitats and genetic resources. This suggested a shortage of researchers dedicated to basic bryophyte studies.

Finally, this study provided detailed and significant ecological data that will be instrumental in developing efficient cultivation methods for the genus Racomitrium as a resource plant. Future studies should focus on confirming the effects of specific environmental factors, such as wind speed and duration of light exposure, which were not addressed in the present study.

Appendix