Pinus arvensis - Pinus arvensis

A perennial evergreen fern of the family Fructaceae. Its rhizome has no roots and branches underground. The aboveground stem is 10-35 cm tall, and has a broom-like appearance with repeated bifurcated branches. The twigs are 1-1.5 mm in diameter, triangular in cross section, and bare except for small claw-like leaves scattered about. The sporangia are enclosed in bifurcated protruding leaves and grow on the twigs. They are about 2 mm in diameter and divided into three chambers, each of which splits vertically when it ripens and turns yellow. Although it is a fern, the prothallus is rod-shaped rather than cordate, and has intermittent vascular bundles. It is rarely found in the mountains south of the southern Kanto region, and grows on trees and rocks. Since the Edo period, many varieties have been created as ornamental plants along with Selaginella hiba. It can be easily grown in a pot with fine, well-drained sand mixed with Kanuma soil and water moss, but in areas north of the Kanto region, it must be overwintered in a greenhouse. The Japanese pine baran is said to be a survivor of the non-leafy plants (psilophyton) that flourished in the Paleozoic era, but there are many other theories.

[Harufumi Nishida]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

マツバラン科の多年生常緑性シダ。根茎は根をもたず、地下を分枝しながらはう。地上茎は高さ10～35センチメートル、二叉(にさ)の分枝を繰り返して箒(ほうき)状の外形になる。小枝は径1～1.5ミリメートルで断面は三角形、爪(つめ)状の小さな葉をまばらにつける以外は裸である。胞子嚢(のう)は二叉に分かれた突起状の葉に抱かれて小枝上に生じ、径は約2ミリメートルで、中は3室に分かれ、それぞれ熟して黄色くなると縦に割れる。シダ植物ではあるが、前葉体は心臓形にならず棒状で、断続する維管束をもつ。関東地方南部以南の山中にまれに産し、樹上や岩上に着生する。江戸時代からイワヒバとともに観葉植物として多くの品種がつくりだされた。小粒の水はけのよい砂に、鹿沼土(かぬまつち)や水苔(みずごけ)を混ぜて鉢植えにすれば容易に栽培できるが、関東地方以北では温室で越冬させる必要がある。マツバランは、古生代に繁茂した無葉類（プシロフィトン類）の生き残りであるとされるが、異説も多い。

［西田治文］

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