Table 1 Comparison of morphological characteristics of D. japonica
Characters | Womersley (1987) (as D. ligulata) | Yoshida (1998) (as D. ligulata) | Yang et al. (2014) (as D. japonica) | Korean specimens (in this study) |
|---|---|---|---|---|
Color | Medium brown to greenish brown | – | Light olive brown | Light olive brown |
Height | Usually 20–50 cm tall | 60–100 cm tall | 0.6–1 (− 2) m tall | 40–67 cm |
Width of branches | With axis and primary laterals mostly 2–5 mm broad | 3–6 mm wide branches | 2–6 (− 20) mm wide branches | (0.7 −) 1.7–4 mm wide branches |
Holdfast | Discoid holdfast | – | Conical or flattened | Discoid holdfast |
Branching type | Fronds with frequent opposite branching to 3 orders | Opposite to ca. three times branching | Opposite, branches of limited growth branched to two to three times | Opposite, branched to two to three times |
Branch morphology | More or less linear but tapering apically and basally, dentate, and with a faint to conspicuous midrib (the axial filament) | Wide linear feather-like branches, tapering apically and basally with midrib | Branches stipitate and attenuate at base and apex | Branches stipitate and attenuate at base and apex |