Inomotosou - Inomotosou

An evergreen fern of the Pterocallidaceae family. It has a short rhizome with dark brown scales. Its leaves are papery and consist of vegetative and sporophylls. The vegetative leaves are small, with pinnae about 8 mm wide and shallowly toothed edges, which run linearly along the axis and form wings. The sporophylls are much larger than the vegetative leaves, reaching lengths of up to 60 cm, and bearing long clusters of sporangia along the edges of the pinnae. It is widely distributed in areas west of the Kanto region, and is often seen on plains and at the foot of mountains. The closely related P. cretica is even larger, with vegetative leaves reaching lengths of 60 cm, pinnae 3 cm wide, and no wings on the central axis. The sporophylls are longer than the vegetative leaves and have narrower pinnae. It is commonly found in the forest undergrowth of mountainous areas west of the Kanto and Hokuriku regions. P. nipponica resembles P. nipponica, but its leaves are dark green and somewhat thick, with noticeable white spots along the center axis of the pinnae, and it is widely cultivated as an ornamental plant both in Japan and overseas. It is found in warm areas of Honshu, Shikoku, and Kyushu, but is rare. It grows well in pots and prefers well-drained soil, but be careful not to let it dry out.

[Harufumi Nishida]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

イノモトソウ科の常緑性シダ。根茎は短く、黒褐色の鱗片(りんぺん)がある。葉は洋紙質で、栄養葉と胞子葉がある。栄養葉は小さく、羽片は幅8ミリメートル前後で縁(ふち)には浅い鋸歯(きょし)があり、線形で軸に沿って流れ、翼をつくる。胞子葉は栄養葉よりはるかに大きく、長さ60センチメートルに達し、羽片の縁に沿って長く胞子嚢(ほうしのう)群をつける。関東地方以西の各地に広く分布し、平地や山麓(さんろく)では、よくみかける。近縁のオオバノイノモトソウP. creticaはさらに大形で、栄養葉は長さ60センチメートルに達し、羽片の幅も3センチメートルになり、中軸には翼がない。胞子葉は栄養葉より長く、羽片の幅が狭い。関東、北陸以西の山地の林下などに普通にみられる。マツザカシダP. nipponicaはオオバノイノモトソウに似るが、葉は濃緑色でやや質が厚く、羽片の中軸に沿って著しい白斑(はくはん)があり、観葉植物として広く国内外で栽培される。本州、四国、九州の暖地に産するが、まれである。栽培は鉢植えがよく、水はけのよい培土を好むが、乾燥に注意する。

［西田治文］

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