Epicormic Shoots in a Permian Gymnosperm from Antarctica
Epicormic Shoots in a Permian Gymnosperm from Antarctica
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DOI：
10.1086/654849
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发表时间：
2010-09
影响因子：
2.3
通讯作者：
Anne‐Laure Decombeix;E. Taylor;T. N. Taylor
中科院分区：
文献类型：
--
作者：
Anne‐Laure Decombeix;E. Taylor;T. N. Taylor
来自南极洲晚二叠世的两个保存完好的裸子植物树干被描述为带有丛生的裸子植物幼芽。保存最完好的树干有14厘米长。它有一个小的圆形薄壁组织髓和9厘米的次生木质部，包含至少50个生长轮。第二个样本稍小(\DocentClass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{extcomp}\usepackage{portland，xspace}\usepackage{amsath，amsxtra}\usepackage[OT2，OT1]{Fontenc}\NewCommand\Cyr{\renewCommand\rmDefault{wncyr}\renewCommand\sfDefault{wncyss}\renewCommand\encodingDefault{OT2}\NORMANT\SELECTFONT}\DeclareTextFontCommand{\extcyr}{\Cyr}\PageStyle{Empty}\DeclareMathSizes{10}{9}{7}{6}\Begin{Document}\横向$11\Times 8$$\end{Document}cm)，有20个增长年轮。这两个标本都有氧化木质，在树干表面的分界线上产生了50多个小枝。枝条具有宽阔的薄壁组织髓，髓可实心至隔开，端头初生木质部形成8-10个合轴，少量次生木质部与亲本树干相似。枝条向主干外侧分枝，数量增多。根据该遗址的解剖学比较和联系，证据表明，这些标本可能代表了一些舌翅目的树干，这是冈瓦那二叠纪种子蕨类的优势类群。这是首次报道在古生代裸子植物中发现的一簇簇的裸子植物。产生大量能够发育成新枝的幼芽的能力表明，这些高纬度树木具有建筑可塑性，使它们能够对短期或长期的环境胁迫做出快速反应。
Two anatomically preserved gymnosperm trunks with clusters of epicormic shoots are described from the Late Permian of Antarctica. The best‐preserved trunk is 14 cm long. It has a small circular parenchymatous pith and 9 cm of secondary xylem that contains at least 50 growth rings. The second specimen is slightly smaller ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $$11\times 8$$ \end{document} cm) and has 20 growth rings. Both specimens have pycnoxylic wood and produced more than 50 small shoots in a delimited zone on the surface of the trunk. Shoots have a wide parenchymatous pith that may be solid to septate with endarch primary xylem forming 8–10 sympodia and a small amount of secondary xylem similar to that of the parent trunk. The shoots branch and increase in number toward the outside of the trunk. Evidence based on anatomical comparisons and association at the site indicates that the specimens probably represent trunks of some glossopterid, the dominant group of seed ferns during the Permian in Gondwana. This is the first report of clusters of epicormic shoots in a Paleozoic gymnosperm. The ability to produce a large number of young shoots that were capable of developing into new branches indicates that these high‐latitude trees possessed an architectural plasticity that allowed them to respond quickly to short‐ or long‐term environmental stress.