| 单词 | fern |
| 释义 | fern[ furn ] / fɜrn / SEE SYNONYMS FOR fern ON THESAURUS.COM nounany seedless, nonflowering vascular plant of the class Filicinae, of tropical to temperate regions, characterized by true roots produced from a rhizome, triangular fronds that uncoil upward and have a branching vein system, and reproduction by spores contained in sporangia that appear as brown dots on the underside of the fronds. Origin of fernbefore 900; Middle English ferne,Old English fearn; cognate with German Farn fern, Sanskrit parná feather OTHER WORDS FROM fernfernless, adjectivefernlike, adjectiveWords nearby fernFermi energy, Fermi, Enrico, fermion, fermium, Fermor, fern, Fernandel, Fernandez, Fernández de Lizardi, Fernando de Noronha, Fernando I Definition for fern (2 of 2)Fern [ furn ] / fɜrn / nouna female given name. Dictionary.com UnabridgedBased on the Random House Unabridged Dictionary, © Random House, Inc. 2020 Example sentences from the Web for fernBritish Dictionary definitions for fernfern / (fɜːn) / nounany tracheophyte plant of the phylum Filicinophyta, having roots, stems, and fronds and reproducing by spores formed in structures (sori) on the frondsSee also tree fern any of certain similar but unrelated plants, such as the sweet fern Derived forms of fernfernlike, adjectiveferny, adjectiveWord Origin for fernOld English fearn; related to Old High German farn, Sanskrit parná leaf Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012 Scientific definitions for fernfern [ fûrn ] Any of numerous seedless vascular plants belonging to the phylum Pterophyta that reproduce by means of spores and usually have feathery fronds divided into many leaflets. Most species of ferns are homosporous (producing only one kind of spore). The haploid spore grows into a small, usually flat gametophyte known as a prothallus, which is undifferentiated into roots, stems, and leaves. The green prothallus anchors itself with hairlike extensions known as rhizoids and bears both archegonia (organs producing female gametes) and antheridia (organs producing male gametes). The male gametes require the presence of water to swim to the female gametes and fertilize the eggs. Normally only one embryo is produced, and it then grows out of the gametophyte plant as a diploid sporophyte plant that has roots, stems, and leaves and conducts photosynthesis, while the smaller gametophyte withers away. The leaves of these sporophytes eventually produce sporangia (in some species occurring in clusters known as sori). Under dry conditions, the sori burst releasing hundreds of thousands or millions of spores. Ferns were abundant in the Carboniferous period and exist today in about 11,000 species, about three-quarters of which live in tropical climates. The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved. |
| 随便看 |
英语词典包含192737条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。