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Asteroxylon
''Asteroxylon'' ("star-shaped xylem") is an extinct genus of vascular plants of the Division Lycopodiophyta known from anatomically preserved specimens described from the famous Early Devonian Rhynie chert and Windyfield chert in Aberdeenshire, Scotland. ''Asteroxylon'' is considered a basal member of the Lycopsida. Description ''Asteroxylon'' is a genus of terrestrial vascular plant which flourished in the Early Devonian period. This plant consisted of aerial, isotomously and anisotomously branching stems that reached 12 mm in diameter and 40 cm in length. The possibly procumbent aerial stems arose from a leaf-less rhizome which bore smaller-diameter, positively geotropic root-like branches. The rhizomes, which represent an independent origin of roots, reached a depth of up to 20 cm below the surface. A 407 million-year-old fossil from the Rhynie chert shows the roots formed through a modified version of a mechanism called “dichotomous branching”, where one ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drepanophycales
Drepanophycales is an order of extinct lycopsid plants of Late Silurian to Late Devonian age (around ), found in North America, China, Russia, Europe, and Australia. Sometimes known as the Asteroxylales or Baragwanathiales. Description Extinct terrestrial vascular plants of the Silurian to Devonian periods. Stem of the order of several mm to several cm in diameter and several cm to several metres long, erect or arched, dichotomizing occasionally, furnished with true roots at the base. Vascular bundle an exarch actinostele, tracheids of primitive annular or helical type (so-called G-type). Stem clothed in either microphylls (leaves with a single vascular thread or 'vein'), or with leaf-like enations (unvascularized projections) with a vascular trace into the base of each enation. Homosporous, with sporangia borne singly and dehiscing by a single slit. List of families The following families have, at various times, been segregated within the Drepanophycales. However, Kenrick and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nothia Aphylla
''Nothia'' was a genus of Early Devonian vascular plants whose fossils were found in the Rhynie chert in Scotland. It had branching horizontal underground stems (rhizomes) and leafless aerial stems (axes) bearing lateral and terminal spore-forming organs (sporangia). Its aerial stems were covered with small 'bumps' (emergences), each bearing a stoma. It is one of the best described early land plants. Its classification remains uncertain, although it has been treated as a zosterophyll. There is one species, ''Nothia aphylla''. History of discovery Fossilized remains, including bare stems (axes) and detached spore-forming organs (sporangia), were first described by Kidston and Lang in 1920 from the Rhynie chert of Aberdeenshire, Scotland – rocks which are of Pragian age (). The fragments were considered to be parts of ''Asteroxylon mackiei''. In 1964 Lyon described sporangia belonging to ''Asteroxylon mackiei'' and suggested that Kidston and Lang's specimens were a new species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nothia (plant)
''Nothia'' was a genus of Early Devonian vascular plants whose fossils were found in the Rhynie chert in Scotland. It had branching horizontal underground stems (rhizomes) and leafless aerial stems (axes) bearing lateral and terminal spore-forming organs (sporangia). Its aerial stems were covered with small 'bumps' (emergences), each bearing a stoma. It is one of the best described early land plants. Its classification remains uncertain, although it has been treated as a zosterophyll. There is one species, ''Nothia aphylla''. History of discovery Fossilized remains, including bare stems (axes) and detached spore-forming organs (sporangia), were first described by Kidston and Lang in 1920 from the Rhynie chert of Aberdeenshire, Scotland – rocks which are of Pragian age (). The fragments were considered to be parts of ''Asteroxylon mackiei''. In 1964 Lyon described sporangia belonging to ''Asteroxylon mackiei'' and suggested that Kidston and Lang's specimens were a new species ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lycopodiophyta
The lycophytes, when broadly circumscribed, are a vascular plant (tracheophyte) subgroup of the kingdom Plantae. They are sometimes placed in a division Lycopodiophyta or Lycophyta or in a subdivision Lycopodiophytina. They are one of the oldest lineages of extant (living) vascular plants; the group contains extinct plants that have been dated from the Silurian (ca. 425 million years ago). Lycophytes were some of the dominating plant species of the Carboniferous period, and included tree-like species, although extant lycophytes are relatively small plants. The scientific names and the informal English names used for this group of plants are ambiguous. For example, "Lycopodiophyta" and the shorter "Lycophyta" as well as the informal "lycophyte" may be used to include the extinct zosterophylls or to exclude them. Description Lycophytes reproduce by spores and have alternation of generations in which (like other vascular plants) the sporophyte generation is dominant. Some lycophyte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhyniophytina
The rhyniophytes are a group of extinct early vascular plants that are considered to be similar to the genus ''Rhynia'', found in the Early Devonian (around ). Sources vary in the name and rank used for this group, some treating it as the class Rhyniopsida, others as the subdivision Rhyniophytina or the division Rhyniophyta. The first definition of the group, under the name Rhyniophytina, was by Banks, since when there have been many redefinitions, including by Banks himself. "As a result, the Rhyniophytina have slowly dissolved into a heterogeneous collection of plants ... the group contains only one species on which all authors agree: the type species ''Rhynia gwynne-vaughanii''". When defined very broadly, the group consists of plants with dichotomously branched, naked aerial axes ("stems") with terminal spore-bearing structures (sporangia). The rhyniophytes are considered to be stem group tracheophytes (vascular plants). Definitions The group was described as a subdivision of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Baragwanathia
''Baragwanathia'' is a genus of extinct lycopsid plants of Late Silurian to Early Devonian age (), fossils of which have been found in Australia, Canada, China and Czechia. The name derives from William Baragwanath who discovered the first specimens of the type species, ''Baragwanathia longifolia'', at Thomson River (Victoria, Australia). Description ''Baragwanathia'' differed from such taxa as ''Asteroxylon'' by the presence of vascular tissue in its leaves—''Asteroxylon'' had enations without vascular tissue. The sporangia were borne in the axils of the leaves, which were spirally arranged. By comparison, the closely related genus ''Drepanophycus'' of the same period (see Drepanophycaceae for more details) bore its sporangia on the upper surface of specialized leaves known as sporophylls. ''Baragwanathia'' varied in size, with stems up to a few cm in diameter and up to a few metres in length. They were erect or arched, dichotomized (forked) occasionally, and had adventit ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lycopsida
Lycopodiopsida is a class of vascular plants known as lycopods, lycophytes or other terms including the component lyco-. Members of the class are also called clubmosses, firmosses, spikemosses and quillworts. They have dichotomously branching stems bearing simple leaves called microphylls and reproduce by means of spores borne in sporangia on the sides of the stems at the bases of the leaves. Although living species are small, during the Carboniferous, extinct tree-like forms formed huge forests that dominated the landscape and contributed to coal deposits. The nomenclature and classification of plants with microphylls varies substantially among authors. A consensus classification for extant (living) species was produced in 2016 by the Pteridophyte Phylogeny Group (PPG I), which places them all in the class Lycopodiopsida, which includes the classes Isoetopsida and Selaginellopsida used in other systems. (See Table 2.) Alternative classification systems have used ranks fr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windyfield Chert
The Rhynie chert is a Lower Devonian sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield chert, is located some 700 m away. The Rhynie chert contains exceptionally preserved plant, fungus, lichen and animal material preserved in place by an overlying volcanic deposit. The bulk of the Devonian fossil bed consists of primitive plants (which had water-conducting cells and sporangia, but no true leaves), along with arthropods, lichens, algae and fungi. This fossil bed is remarkable for two reasons. First, the age of the site ( Pragian, Early Devonian, formed about ) places it at an early stage in the colonisation of land. Second, these cherts are famous for their exceptional state of ultrastructural preservation, with individual cell walls easily visible in polished specimens. Stomata have been counted and lignin remnants detected in t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhynie Chert
The Rhynie chert is a Lower Devonian sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield chert, is located some 700 m away. The Rhynie chert contains exceptionally preserved plant, fungus, lichen and animal material preserved in place by an overlying volcanic deposit. The bulk of the Devonian fossil bed consists of primitive plants (which had water-conducting cells and sporangia, but no true leaves), along with arthropods, lichens, algae and fungi. This fossil bed is remarkable for two reasons. First, the age of the site ( Pragian, Early Devonian, formed about ) places it at an early stage in the colonisation of land. Second, these cherts are famous for their exceptional state of ultrastructural preservation, with individual cell walls easily visible in polished specimens. Stomata have been counted and lignin remnants detected in the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Early Devonian Land Plants
The list of Early Devonian (419.2 ± 2.8 to 393.3 ± 2.5 million years ago) land plants includes currently known vascular and potentially vascular plants, along with some possibly non-vascular plants, that have been described from global Early Devonian fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ... assemblages. List of land plants References {{reflist * * * * See also * Devonian Devonian plants ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microphyll
In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concept of a microphyll, the leaf vein emerges from the protostele without leaving a leaf gap. Leaf gaps are small areas above the node of some leaves where there is no vascular tissue, as it has all been diverted to the leaf. Megaphylls, in contrast, have multiple veins within the leaf and leaf gaps above them in the stem. Leaf vasculature The clubmosses and horsetails have microphylls, as in all extant species there is only a single vascular trace in each leaf. These leaves are narrow because the width of the blade is limited by the distance water can efficiently diffuse cell-to-cell from the central vascular strand to the margin of the leaf. Despite their name, microphylls are not always small: those of ''Isoëtes'' can reach 25 centimetres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drepanophycus
''Drepanophycus'' is a genus of extinct plants of the division Lycopodiophyta of Early to Late Devonian age (around ), found in Eastern Canada and Northeast US, China, Russia, Egypt and various parts of Northern Europe and Britain. Description Extinct terrestrial vascular plants of the Devonian period. Stem of the order of several mm to several cm in diameter and several cm to a metre long, erect or arched, dichotomizing occasionally, furnished with true roots at the base. Vascular bundle actinostele, tracheids of primitive annular or helical type (so-called G-type). Leaves are unbranched thorn-shaped (i.e. with a wide base, tapering to a blunt point) microphylls several mm long with a single prominent vascular thread, arranged spirally to randomly on the stem. Sporangia borne singly on the upper leaf surface. ''Drepanophycus'' has similarities to the genus ''Halleophyton''. It differs from a closely related genus of the same period, Baragwanathia, in the position of the sporang ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
