Spore leaves - How

A general term for leaves that have the function of forming spores, also called fruit leaves, and the opposite of vegetative leaves (bare leaves). In most ferns that produce homospores (spores that are not gender-specific in size), the morphological and functional differences between sporophylls and vegetative leaves are often not very clear. Such sporophylls have chloroplasts and often function as vegetative leaves after spore dispersal, so they are called vegetative sporophylls. Even in ferns that produce homospores, such as Osmundae, Acanthaceae, Phylloferidae, and Acanthaceae, sporophylls are differentiated into sporophylls and vegetative leaves, and sporophylls wither or lose their leaf function after spore dispersal. In ferns that produce heterospores (spores that are gender-specific in size, etc.), a distinction is made between megasporophylls that produce only megaspores and microsporophylls that produce only microspores. These correspond to the carpels and stamens of seed plants, respectively. In some species of kelp, the parts of the thallus that produce reproductive cells are called sporophylls, although they are not true leaves.

[Yasuda Keisuke]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

胞子を形成する機能を有する葉の総称で、実葉ともいい、栄養葉（裸葉）の対語。同形胞子（大きさのうえで雌雄性の区別がない胞子）を生じる大多数のシダ類では、胞子葉と栄養葉との間に形態的、機能的差異があまり顕著でない場合が多い。このような胞子葉は、葉緑体をもち、胞子散布後は栄養葉としての機能を果たすものが多いので、栄養胞子葉とよばれる。同形胞子を生じるシダ類でも、ゼンマイ科、ハナワラビ科、キジノオシダ科、シシガシラ属などでは、胞子葉と栄養葉とが分化しており、胞子葉は胞子散布後に枯れるか、または葉としての機能を失う。異形胞子（雌雄性によって大きさなどに区別がある胞子）を生じるシダ植物では、大胞子のみを生じる大胞子葉、小胞子のみを生じる小胞子葉とが区別される。これらは、それぞれ種子植物の心皮(しんぴ)と雄蕊(ゆうずい)に相当する。またコンブ類の一部では、真正の葉ではないが、生殖細胞群を生じる葉状体の部分を胞子葉とよぶことがある。

［安田啓祐］

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