Fern seeds (Fern seeds) - Shida Shushirui (English spelling) seed ferns

Japanese: シダ種子類(羊歯種子類) - しだしゅしるい（英語表記）seed ferns

Pteridospermopsida is an extinct gymnosperm class. Its leaves are pinnately compound like ferns, but they bear seeds instead of sporangia as reproductive organs. It is the starting point of seed plants, and made a great evolution in the late Paleozoic era. Some species survived into the Mesozoic era, but most are thought to have become extinct at the end of the Paleozoic era. It is indistinguishable from ferns because of its leaves that do not bear reproductive organs, and the two species are collectively referred to as fern-like fronds, with morphogenetic genera such as Pecopteris and Sphenopteris .

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

裸子植物の絶滅綱Pteridospermopsida。葉はシダ型の羽状複葉だが，繁殖器官として胞子囊ではなく種子を葉につける。種子植物の出発点となる植物で，古生代後期に大発展をとげた。中生代に一部を残したが，大部分は古生代末に絶滅したと考えられている。繁殖器官をつけない葉ではシダ類と区別がつかず，両者を合わせてシダ状葉fern like frondsとしてペコプテリスPecopteris，スフェノプテリスSphenopterisなどの形態属が使用されている。

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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