Isoetalean lycopsid evolution: from the Devonian to the present
Isoetalean lycopsid evolution: from the Devonian to the present
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DOI：
10.1640/0002-8444(2001)091
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发表时间：
2001-07-01
影响因子：
0.8
通讯作者：
Pigg, KB
中科院分区：
文献类型：
--
作者：
Pigg, KB
isoetean石松类植物的进化跨越了维管植物的大部分历史，从泥盆纪晚期（或可能是中期）到现在的Isoetes属。这一类群中最著名的化石成员是占主导地位的晚石炭世煤沼泽的乔木鳞片树。具有细长茎的简单的无分枝等柱类也早于煤沼泽树，与之共存，并在其之后存在，一直延伸到中生代。尽管某些突触形态，如柱头根，双极生长和次级组织将进化枝统一起来，但其他特征表征了不同年龄，生长形式和可能的进化谱系的较小亚群。尽管这些特征在特定时期的植物中是众所周知的，特别是石炭纪，但整个群体的特征进化趋势从未得到充分的记录。更好地了解整个等古宙化石记录的这种趋势，对于区分进化谱系和趋同谱系可能是有价值的。有趣的是，早在三叠纪就出现了现代Isoetes的一些形态特征。单粒小孢子，下陷孢子囊和带舌足的精致舌体出现在长茎三叠纪形态中。现代Isoetes的主要植物习性是一种减少的伞形植物，缺乏明显的茎伸长，至少起源于侏罗纪，是中生代晚期和新生代Isoetes的典型特征。
The evolution of the isoetalean lycopsids spans much of the history of vascular plants, from Late, (or possibly Middle), Devonian to the current day genus Isoetes. The best known fossil members of this group are the arborescent lepidodendrids that dominated the Late Carboniferous coal swamps. Simpler unbranched isoetaleans with elongate stems also predated, coexisted with, and postdated the coal swamp trees, extending well into the Mesozoic. Whereas certain synapomorphies such as stigmarian rootlets, bipolar growth and secondary tissues unite the clade, other features characterize smaller subgroups of differing age, growth form and possibly, evolutionary lineage. Although some of these features are well known for plants of given time periods, particularly the Carboniferous, trends in character evolution have never been adequately documented for the group as a whole. A better understanding of such trends throughout the isoetalean fossil record could be valuable in distinguishing evolutionary lineages from convergence. It is interesting that several morphological characters of modern Isoetes are present as early as the Triassic. monolete microspores, sunken sporangia and elaborate ligules with glossopodia occur within elongate-stemmed Triassic forms. The dominant plant habit of modern Isoetes, a reduced cormose form that lacks appreciable stein elongation, originated at least by the Jurassic and typifies late Mesozoic and Cenozoic isoetaleans.