• fern
  • Any of a large number of vascular plants composing the division Polypodiophyta, without flowers and fruits.
Abstract from DBPedia
    A fern (Polypodiopsida or Polypodiophyta /ˌpɒliˌpɒdiˈɒfɪtə, -əˈfaɪtə/) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pteridophytes except the lycopods, and differ from mosses and other bryophytes by being vascular, i.e., having specialized tissues that conduct water and nutrients and in having life cycles in which the branched sporophyte is the dominant phase. Ferns have complex leaves called megaphylls, that are more complex than the microphylls of clubmosses. Most ferns are leptosporangiate ferns. They produce coiled fiddleheads that uncoil and expand into fronds. The group includes about 10,560 known extant species. Ferns are defined here in the broad sense, being all of the Polypodiopsida, comprising both the leptosporangiate (Polypodiidae) and eusporangiate ferns, the latter group including horsetails, whisk ferns, marattioid ferns, and ophioglossoid ferns. Ferns first appear in the fossil record about 360 million years ago in the late Devonian period, but many of the current families and species did not appear until roughly 145 million years ago in the early Cretaceous, after flowering plants came to dominate many environments. The fern Osmunda claytoniana is a paramount example of evolutionary stasis; paleontological evidence indicates it has remained unchanged, even at the level of fossilized nuclei and chromosomes, for at least 180 million years. Ferns are not of major economic importance, but some are used for food, medicine, as biofertilizer, as ornamental plants, and for remediating contaminated soil. They have been the subject of research for their ability to remove some chemical pollutants from the atmosphere. Some fern species, such as bracken (Pteridium aquilinum) and water fern (Azolla filiculoides) are significant weeds worldwide. Some fern genera, such as Azolla, can fix nitrogen and make a significant input to the nitrogen nutrition of rice paddies. They also play certain roles in folklore.

    シダ類(シダるい、羊歯類、英: Ferns)は、一般に「シダ」(羊歯、歯朶)と総称される維管束植物の一群である。伝統的分類および一般的な文脈では、薄嚢シダ類に加え、合わせてとも呼ばれるリュウビンタイ目とハナヤスリ目を含む分類群を指す。 かつてはシダ植物の伝統的分類において、マツバラン類(無葉類)、ヒカゲノカズラ類(小葉類)およびトクサ類(楔葉類)とともにシダ類(大葉類)としてシダ植物に含められ、多くシダ綱(シダこう、Pteridopsida, Filicopsida)として綱の階級に置かれた。1920年代以降、系統的に4群が遠いと考えられるようになり、シダ門 Pterophytaやシダ類亜門 Pterophytinaとしてより上位の分類階級に置くこともあった。しかし分子系統解析により、シダ植物だけでなくシダ類自身も側系統群であることが判明し、本項の示す「シダ類」は分類群としては現在ではもはや用いられない。なお、の分類体系では「シダ綱 Filicopsida」は薄嚢シダ類を指す分類群として用いられていた。 近年では分子系統解析により、伝統的なシダ類にマツバラン類およびトクサ類を含めたグループが単系統群をなすことが明らかになっており、それをまとめて「シダ類 ferns」と呼ぶことも多くなっている。このグループはにおいて "Moniliformopses" と呼ばれた群に相当し、「モニロファイツ」や「大葉シダ類」と呼ばれることも多く、この単系統群については「大葉シダ植物」にて解説する。

    (Source: http://dbpedia.org/resource/Fern)