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The Caytoniales is an extinct order of seed plants whose presence is recorded in fossils collected throughout the Mesozoic Era (around ). The plants are part of the group called seed ferns because they are seed-bearing plants with fern-like leaves.〔 The first fossils to be identified in this order were discovered in a Middle Jurassic formation in Yorkshire. The plants are believed to have grown in wetlands of some nature and may have been small trees. They are considered a gymnosperm by many botanical authorities, but were once thought to have an evolutionary relationship with the angiosperms, or flowering plants, because their seeds are born in a partially enclosed cupule (a modified leaf with reproductive organs).〔 The leaves are palmately compound with 3-6 leaflets 2-6cm in length.〔 The pollen grains are winged, like those of gymnosperms, and the pollen is bisaccate like the pollen of pine trees.〔 ==Form taxa== *''Sagenopteris'' -- leaves *''Caytonanthus'' -- microsporophyll, or pollen producing organ *''Caytonia'' -- ovule 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Caytoniales」の詳細全文を読む スポンサード リンク
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