docEvolution of leaves (microphylls, megaphylls)
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Evolution of leaves (microphylls, megaphylls)
Fossil History of Plants Lecture 7 Evolution of stems, leaves (microphylls, megaphylls), and roots; origin of major groups Evolution of major vascular plant clades Lycopopods Euphyllophytes Isoetales Lepidodendrales Selaginellales Lycopodiales Protolepidodendrales Seed Plants Progymnosperms Equisetophytes Ferns Psilotophytes Lycophytina Euphyllophytina Trimerophytes Zosterophylls Rhyniophytes Banks, 1968 T Z R The first land plants Trimerophytes Rhyniophytes Zosterophylls Rhyniophytes Raven et al., 2005 Evolution of major vascular plant clades Lycopopods Isoetales Lepidodendrales Selaginellales Lycopodiales Protolepidodendrales Lycophytina Euphyllophytina Zosterophylls Rhyniophytes Drepanophycus spinaeformis Lepidodendron sp. Lycopodium sp. T Z R Banks, 1968 Evolution of Lycophyte leaves (microphylls) Lycophytina Euphyllophytina Zosterophylls Trimerophytes Rhyniophytes Evolution of microphylls From enations Banks, 1968 Zosterophylls Drepanophycus spinaeformis 1. Enations (in some) 2. Lateral sporangia 3. Exarch stele Protolepidodendron Oldest lycopod – Baragwanathia Upper Silurian Asteroxylon (Rhynie Chert) Asteroxylon stem - enations or leaves? 1. Definite arrangement 2. No vascular bundle in leaf Enations have 1. No definite arrangement 2. No vascular tissue Leaves have 1. Definite arrangement 2. Vascular bundle(s) Evolution of Roots – downward growth of axes Drepanophycus spinaeformis, Gensel et al., 2005 Asteroxylon Parallel evolution of giant trees 1. Tropisms 2. Bipolar growth Lepidocarpon Shoot Foot Evolution of Euphyllophyte leaves (megaphylls) Lycophytina Euphyllophytina Trimerophytes Zosterophylls Rhyniophytes Banks, 1968 Evolution of megaphylls From modified branching systems Traditional Paleontological Methodology Evolution of Stem/Leaf Organography Successive change through time = transformational series after Stewart, 1964 Punch’s Almanack, 1882 Ferns Order: Cladoxylales Middle Devonian - Mississippian • Cladoxylon, Pseudosporochnus, Rhymokalon, Hyenia, Calamophyton Order : Rhacophytales, Upper Devonian • Rhacophyton Order: Stauropteridales, Upper Devonian - Mississippian • Stauropteris, Gillespiea Order : Zygopteridales, Devonian - Permian • Zygopteris=stem, Etapteris=petiole, Biscalitheca= sprg Order : Marattiales, Carboniferous - Recent • Psaronius=stem+roots, Pecopteris=frond, Scolecopteris=fertile frond with synangia Order: Ophioglossales, Jurassic - Recent • Botrychium Order: Filicales, Mississippian - Recent + Hydropteridales, Jurassic – Recent • Numerous families, 11,000 species Pseudosporochnus Cladoxylon scoparium Rhacophyton How far along this series is Rhacophyton? Sphenopsida • Pseudoborniales – Devonian (little known) • Noeggerathiales– Carboniferous-Triassic • Cladoxylales – Upper Devonian-Mississippian; Pseudosporochnus, Cladoxylon scoparium • Sphenophyllales – U. Devonian-Permian; understory swamp plants, vines; Sphenophyllum • Calamitales – Devonian-Permian; 2nd dominant in coal swamps of Carboniferous; Calamites, Annularia, Asterophyllites, Calamostachys • Equisetales – Triassic – Recent; Equisetum Equisetum horsetail or scouring rush Calamitales Lignophytes = Progymnosperms + Seed Plants Lignophytes Origin of Wood Tomescu, 2008 Multiple origins of the Euphyllophyte megaphyll Lignophytes Tomescu, 2008 Lignophytes, Progymnosperms, and Seed Plants Archaeopteris, and the origin of seed plants Lignophytes 375 MYO Wood Tomescu, 2008 Archaeopteris sp. Evolution of major vascular plant clades Lycophytina Euphyllophytina Evolution of megaphylls From modified branching systems Trimerophytes Zosterophylls Evolution of microphylls From enations Rhyniophytes Banks, 1968