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PALAEOBOTANICAL RESEARCH   GROUP   UNIVERSITY  MÜNSTER

All modern clubmosses or lycopods are small herbaceous plants. Most of their late Palaeozoic, particularly their Carboniferous relatives were large trees. Several genera are known. One of the best tree-like lycopods is Lepidodendron. Sigillaria is another example of a lycopod tree. Genera are distinguished on the basis of the shape of the leaf cushions on the stems, their anatomy, their reproductive structures and their growth habit. During most of the Westphalian arborescent lycopods were the dominant elements in coal swamp floras and hence also the most important biomass producers. Up to 80% of  the North American and  European Westphalian coals can consist of biomass derived from arborescent lycopods. Tree-like lycopods were heterosporous; in some forms the megaspores with surrounding megasporangia and megasporophylls look almost seed-like. Unlike in any other type of tree which all have secondary growth concentrated in the xylem (wood), the secondary growth of arborescent lycopods mainly took place in the cortex (bark). Several examples of in situ preserved fossil lycopod forest are known. Most arborescent lycopods became extinct by the end of the Westphalian. Apart from arborescent forms also herbaceous lycopods are known. These include homosporous forms similar to most modern lycopods and heterosporous forms similar to the modern Selaginella. Some authors even assign Carboniferous forms to the extant genus Selaginella. If this would be true, this would be the longest living genus of higher land plants.

Taxon / Subject	Web Source	Comments	Pics	Info
Lycophytes	Virtual Paleobotany Laboratory	links to pictures and further info
One of the most common and most widespread Carboniferous tree lycopods is Lepidodendron. The genus was orginally described for stem surfaces showing the characteristic spirally arranged diamond-shaped, vertically positioned leaf cushions. Some Lepidodendron species could be up to ca. 40 m high. Most peculiar is their anatomy showing that the secondary growth mainly took place in the cortex; the proportion of xylem (wood) is relatively small. During their life the trees shed parts of their outer bark and basal parts of the trunks and larges stems typically show various stages of decortication. Lepidodendron trees rooted horizontally, indicating humid environments. Root systems are known as Stigmaria. Several types of branching patterns of aerial stems have been distinguished, on the basis of which the genus has been differentiated into several genera. Branching can be lateral or dichotomous; large branch scars of lateral branches have been described as Ulodendron. Leaves were long, narrow and stiff (Lepidophyllum); those of the the ultimate branches being smaller and needle-like. The plants were heterosporous and some of the strobili, known as Lepidostrobus, could reach a length of nearly 1 m. Isolated sporophylls are known as Lepidostrobophyllum.  Lepidondendron became almost completely extinct by the end of the Westphalian.
Lepidodendron	Hans' (Steur) Paleobotany Page	reconstruction showing different organs
Lepidodendron
Lepidodendron aculeatum	M. Hieb's Plant Fossils of West Virginia	figured upside down
Lepidodendron aculeatum	Geol.-Paläontol. Museum, Universität Münster
Lepidodendron aculeatum	Fossils of Nova Scotia
Lepidodendron obovatum	Museum of Natural History, Sendai	German material  in a Japanese museum !
Lepidodendron obovatum	M. Hieb's Plant Fossils of West Virginia
Lepidodendron worthenii	M. Hieb's Plant Fossils of West Virginia
Lepidodendron	Fossils of Nova Scotia
Lepidodendron	Fossils of Nova Scotia
Lepidodendron	Fossils of Nova Scotia	foliated branches
Lepidodendron	Fossils of Nova Scotia
Lepidodendron	Fossils of Nova Scotia
Lepidodendron	Fossils of Nova Scotia	decorticated axis
Lepidodendron	Manny's Fossil Gallery
Lepidodendron	M. Hieb's Plant Fossils of West Virginia
Lepidodendron	M. Hieb's Plant Fossils of West Virginia	specimen showing Ulodendron aspect
Lepidodendron	M. Hieb's Plant Fossils of West Virginia	specimen showing Ulodendron aspect
Lepidodendron	Mazon Creek Exhibit, Illinois State Museum
Lepidodendron	M. Hieb's Plant Fossils of West Virginia	branching
Lepidodendron	Kansas Fossils, Geol. Museum, Emporia State Univ.
Lepidodendron	Collection Jens-Wilhelm Janzen
Lepidodendron and Stigmaria	R.A. Spicer, The Open University, Milton Keynes
Lepidodendron	Kathleen Pigg's "Plant Fossils and Evolution"
Lepidodendron	Kathleen Pigg's "Plant Fossils and Evolution"	coal ball: cross section of a stem
Lepidodendron	Bot. Soc. America, Online Image Collection	coal ball: cross section, small stem
Lepidodendron	Bot. Soc. America, Online Image Collection	as above, high resolution
Lepidodendron selaginelloides	Bot. Soc. America, Online Image Collection	coal ball; leaf base with ligule
Lepidodendron	Bot. Soc. America, Online Image Collection	as above, high resolution
Lepidodendron	Bot. Soc. America, Online Image Collection	coal ball: cross section
Lepidodendron	Bot. Soc. America, Online Image Collection	as above, high resolution
Lepidodendron	Fossil plants from the Northern Anthracite Coal Field
Lepidodendron	Virtual Paleobotany Laboratory
Lepidophyllum (this genus is also known as Cyperites or Lepidophylloides)
Lepidophyllum sp.	M. Hieb's Plant Fossils of West Virginia	small foliated axes
Lepidophyllum sp.	M. Hieb's Plant Fossils of West Virginia	as above, one with cones
Lepidophyllum sp.	Mazon Creek Exhibit, Illinois State Museum
Lepidophylloides	Virtual Paleobotany Laboratory
Lepidophylloides	Virtual Paleobotany Laboratory
Cyperites bicarinatus	Fossil plants from the Northern Anthracite Coal Field
Lepidostrobus
Lepidostrobus sp.	Mazon Creek Exhibit, Illinois State Museum
Lepidostrobus sp.	M. Hieb's Plant Fossils of West Virginia
Lepidostrobus	Collection Jens-Wilhelm Janzen
Lepidostrobus	Fossil plants from the Northern Anthracite Coal Field
Lepidostrobus	Fossils of Nova Scotia
Lepidostrobus	Fossils of Nova Scotia
Lepidostrobus	Virtual Paleobotany Laboratory	coal ball peel showing anatomy
Lepidostrobus	Virtual Paleobotany Laboratory	coal ball peel showing anatomy
Lepidostrobus sp.	Paläobotanik Münster	anatomically preserved	have a look !
Lepidostrobophyllum
Lepidostrobophyllum sp.	Mazon Creek Exhibit, Illinois State Museum
Lepidostrobophyllum sp.	M. Hieb's Plant Fossils of West Virginia
Lepidostrobophyllum lanceolatum	Fossils of Nova Scotia
Lepidostrobophyllum	Virtual Paleobotany Laboratory
Lepidophloios differs from Lepidodendron in having diamond-shaped leaf cushions that wider than high but also spirally arranged. This tree had the same type of rooting and foliage types as Lepidodendron.
Lepidophloios laricinus	Fossils of Nova Scotia
Lepidophloios laricinus	Fossils of Nova Scotia
Lepidophloios laricinus	Fossils of Nova Scotia
Lepidophloios	Virtual Paleobotany Laboratory
Lepidophloios sp.	Paläobotanik Münster		have a look !
Lepidocarpon is a megasporophyll holding a megasporangium with only a single functional megaspore. The megapsporophyll encloses the megasporangium completely thus giving optimal protection. The whole unit (megasporophyll + megasporangium) is shed from the cone. Lepidocarpon thus already pretty much shows a seed-like morphology.
Lepidocarpon	Virtual Paleobotany Laboratory

Sigillaria is another very common and widepread lycopod tree. Leaf cushions are rhomboidal in outline and usually placed in distinct vertical rows; in some species rows are separated by rigdes. Unlike Lepidodendron, Sigillaria did not branch very often, usually one or two times. Rooting systems and leaves are of the same type as in Lepidodendron. The strobili, known as Sigillariostrobus, were borne directly on the main stem. Most Sigillaria species became extinct by the end of the Westphalian but a few forms survived and persisted into the Permian.
Sigillaria	Museum of Natural History, University of Michigan	reconstruction of a tree
Sigillaria	M. Hieb's Plant Fossils of West Virginia	reconstruction of a tree
Sigillaria
Sigillaria sp.	M. Hieb's Plant Fossils of West Virginia	decorticated stem
Sigillaria brardii	Fossil plants from the Northern Anthracite Coal Field
Sigillaria	Fossil plants from the Northern Anthracite Coal Field	decorticated axis
Sigillaria	Collection Jens-Wilhelm Janzen
Sigillaria	Manny's Fossil Gallery
Sigillaria	Virtual Paleobotany Laboratory
Sigillaria scutellata	Fossils of Nova Scotia
Sigillaria elegans	Fossils of Nova Scotia
Sigillaria tessalata	Fossils of Nova Scotia
Sigillaria tessalata	Fossils of Nova Scotia
Syringodendron sp.	M. Hieb's Plant Fossils of West Virginia	decorticated Sigillaria
Sigillariostrobus
Sigillariostrobus sp.	M. Hieb's Plant Fossils of West Virginia
Stigmaria is the rooting system of tree lycopods, Lepidodendron, Lepidophloios and Sigillaria. The woody, a few times bifurcating axes borne hollow tube-like appendages which had the function of roots.  Such rooting systems are called rhizomorphic; Isoetes is one of the very few modern lycopods with a rhizomorphic rooting system. Stigmaria rootlet beds are very common and often occur underneath coal seams. Most famous are in situ preserved forest stands with several stigmarian tree trunks, e.g. the Fossil Grove in Glasgow (Scotland) and Joggings (Nova Scotia).
Stigmaria ficoides	M. Hieb's Plant Fossils of West Virginia
Stigmaria	Manny's Fossil Gallery
Stigmaria ficoides	Fossils of Nova Scotia
Stigmaria ficoides	Fossils of Nova Scotia
Stigmaria ficoides	Fossils of Nova Scotia
Stigmaria ficoides	Fossils of Nova Scotia
Stigmaria sp	Fossils of Nova Scotia
Stigmaria	Bot. Soc. America, Online Image Collection	cross section
Stigmaria	Bot. Soc. America, Online Image Collection	as above, high resolution
Stigmaria	Virtual Paleobotany Laboratory
Stigmaria	Virtual Paleobotany Laboratory
Stigmaria	Virtual Paleobotany Laboratory	anatomically preserved
Several examples of fossil lycopod forests are known. These forests consist of upright standing tree stumps, i.e. the rooting system and the lower portion of the stem. The Fossil Grove in Glasgow (Scotland) and Joggins (Nova Scotia) are among the most famous.
The Fossil Grove	Hunterian Museum Glasgow
Joggins
Chaloneria is was an up to 2 m high unbranched  heterosporous lycopod with axes up to 10 cm in diameter with roots of the Stigmaria-Isoetes type. The microspores are of the Endosporites type, whereas the megaspores are of the Valvisisporites type. This taxon is known from North American coals balls.
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	longitudinal section through the base
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	cross section
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	bark and outer stem surface
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	phloem
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	fertile and vegetative stems
Endosporites	Kathleen Pigg's "Plant Fossils and Evolution"	microspores of Chaloneria
Valvisisporites	Kathleen Pigg's "Plant Fossils and Evolution"	megaspore of Chaloneria
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	megagametophyte
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	megagametophyte
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	megagametophyte
Chaloneria	Kathleen Pigg's "Plant Fossils and Evolution"	megagametophyte
Lycopodites is a genus for small, herbaceous lycopods
Lycopodites	Kathleen Pigg's "Plant Fossils and Evolution"
Lycopod megaspores
Thomasonia	Bot. Soc. America, Online Image Collection
Thomasonia	Bot. Soc. America, Online Image Collection	as above, high resolution
Minerisporites mirabilis	Bot. Soc. America, Online Image Collection
Minerisporites mirabilis	Bot. Soc. America, Online Image Collection	as above, high resolution
Molaspora lobata	Bot. Soc. America, Online Image Collection
Molaspora lobata	Bot. Soc. America, Online Image Collection	as above, high resolution
Megaspore of Lepidodendron	Virtual Paleobotany Laboratory
Some information on modern lycopods
Modern lycopods	Univ. California Museum of Paleontology, Berkeley

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