The order Cyatheales, which includes the tree ferns, is a taxonomic division of the fern class, Polypodiopsida. No clear morphological features characterize all of the Cyatheales, but DNA sequence data indicate the order is monophyletic. Some species in the Cyatheales have tree-like growth forms, but others have rhizomes. Some species have scales on the stems and leaves, while others have hairs. However, most plants in the Cyatheales are tree ferns and have trunk-like stems up to 10 metres (33 ft) tall. It is unclear how many times the tree form has evolved and been lost in the order.
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標準授權 | 480 x 320 px | JPG | 13 點 |
標準授權 | 800 x 533 px | JPG | 15 點 |
標準授權 | 2121 x 1414 px | JPG | 18 點 |
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標準授權 | 7331 x 4888 px | TIF | 39 點 |
進階授權 | 5184 x 3456 px | JPG | 88 點 |
進階授權 | 5184 x 3456 px | JPG | 88 點 |
進階授權 | 5184 x 3456 px | JPG | 88 點 |