请输入您要查询的英文单词:

 

单词 Rhyniophyta
释义

Rhyniophyta

英语百科

Rhyniopsida

Surface view of a polished piece of Rhynie chert showing many cross-sections of Rhynia stems (axes). Scale bar is 1 cm.

Rhyniopsida is a class of extinct early vascular plants, with one family, Rhyniaceae, found in the Early Devonian (around 419 to 393 million years ago). They are polysporangiophytes, since their sporophytes consisted of branched stems bearing sporangia (spore-forming organs). They lacked leaves or true roots but did have simple vascular tissue. The group was first placed in a subdivision of the division Tracheophyta under the name Rhyniophytina (see Polysporangiophyte: Taxonomy for alternative names). Informally, they are often called rhyniophytes. More recently the name paratracheophytes has been suggested, to distinguish such plants from 'true' tracheophytes or eutracheophytes.

随便看

 

英汉双解词典包含3607232条英汉词条,基本涵盖了全部常用单词的翻译及用法,是英语学习的有利工具。

 

Copyright © 2004-2022 Newdu.com All Rights Reserved
京ICP备09058993号 更新时间:2025/8/8 13:16:22