Mangrove fern

Japanese: ミミモチシダ - みみもちしだ（英語表記）mangrove fern

This evergreen fern is unique to mangrove forests and grows on Iriomote Island in Japan. The rhizomes grow to be huge and tuberous, with clumps of leaves that reach 2m in height. The petioles can be thicker than a thumb, are light brown, blackish brown at the base, and bear large light brown scales. The leaf surface is simply pinnate, and the terminal pinna, like the lateral pinnae, is ovate-oblong with a sharp tip and a circular base. It is leathery and thick. The sporangia are attached to the entire underside of the slightly smaller pinnae, and have no protective organ similar to an enthesium. This type of sporangia attachment, which does not form sporangia clusters, is sometimes called "early-leaf fern-like."

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

マングローブ林に特有の常緑性シダで，日本では西表（いりおもて）島に生育している。根茎は塊状で巨大になり，高さ2mに達する葉を叢生（そうせい）する。葉柄は親指より太くなることもあり，薄茶色で，基部は黒褐色となり，淡褐色で大きい鱗片をつける。葉面は単羽状，頂羽片も側羽片と同じように卵状長楕円形，鋭頭，基部は円形。革質で厚い。胞子囊はやや小さい羽片の裏面全面につき，包膜に類する保護器官はない。胞子囊群をつくらないこのような胞子囊のつきかたを〈ミミモチシダ様〉ということがある。

出典　株式会社平凡社世界大百科事典第２版について　情報

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