Stigmaria: Difference between revisions
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=== Overview === |
=== Overview === |
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The [[Paleozoic]] swamps had [[Lepidodendrales|tree-like |
The [[Paleozoic]] swamps had [[Lepidodendrales|tree-like lycopsids]] that grew up to 50 meters in height, and these lycopsid plants were anchored by an extensive network of branching underground structures with root-like appendages attached to them.<ref name=ClealThomas2005>Cleal, C. J. & Thomas, B. A. (2005). "Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?" ''Geobiology'', ''3'', p. 13-31.</ref> Lycopsids were common plants that lived in low-level swampy areas, and rivers flowing within the [[coal forest]]s of high, dried land, especially during the [[Late Carboniferous]] period or Pennsylvanian age. |
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<ref name=Clealsbook>{{cite book|title=Plant Fossils of the British Coal Measures|author1=Christopher J. Cleal |author2=Barry A.Thomas |publisher=The Palaeontological Association|year=1994|ISBN=0-901702-53-6}}</ref> Analysis of the morphology and anatomy of the stigmarian systems suggests that the axes around the structure were shoot-like, and so they are called [[rhizome]]s or rhizomorphs.<ref name="Hetherington">{{cite journal|last1=Hetherington|first1=AJ|last2=Berry|first2=CM|last3=Dolan|first3=Liam|title=Networks of highly branched stigmarian rootlets developed on the first giant trees|journal=PNAS|date=June 14, 2016|volume=113|issue=24|pages=6695–6700|doi=10.1073/pnas.1514427113|url=http://www.pnas.org/content/113/24/6695.full.pdf?with-ds=yes|access-date=15 February 2017|pmc=4914198|pmid=27226309|doi-access=free}}</ref> In general, common species of ''Stigmaria'' (''Stigmaria ficoides sp.'') have been analyzed extensively to provide an understanding of its morphology and histology.<ref>{{cite book |last1=Williamson |first1=William Crawford |url=https://books.google.com/books?id=KDBPAAAAYAAJ&q=Williamson+,+W.+C.+1887+b+.+A+monograph+on+the+morphology+and+histology+of+Stigmaria+fi+coides+.+Palaeontological+Society+Monographs+40+:+1+%E2%80%93+62+.+%5B9%5D+&pg=PA5 |title=A monograph on the morphology and histology of Stigmaria ficoides |publisher=Palaeontographical society |year=1887 |volume=40}}</ref> |
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=== Appendages ("rootlets") === |
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[[File:Stigmaria fossil root in sandstone (Pottsville Group, Middle Pennsylvanian; Frazeysburg Pit, Muskingum County, Ohio, USA) 5 (28407351158).jpg|thumb|right|A |
[[File:Stigmaria fossil root in sandstone (Pottsville Group, Middle Pennsylvanian; Frazeysburg Pit, Muskingum County, Ohio, USA) 5 (28407351158).jpg|thumb|right|A closeup of the small indents or circular scars where the root-like appendages were attached from the stigmarian rhizome. In sandstone. [[Pottsville Group]] (Middle Pennsylvanian), Frazeysburg Pit, Muskingum County, Ohio, U.S.]] |
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The stigmarian systems had rhizomorph axes that presented circular scars around the |
The stigmarian systems had rhizomorph axes that presented circular scars around the rhizomorph apices of ''Stigmaria'' species, where the root-like appendages were attached to the circular scars. These appendages were branched dichotomously, meaning that there were multiple orders of branching functionality to comprise areas of the stigmarian system. Since the stigmarian systems were root-like, these lateral appendages indicate that these were modified leaves adapted to serve the function of the stigmarian system. ''Stigmaria'' had a complex branching structure; therefore, it is comparable to the rhizomes of the extant (living) relative, the quillworts (genus [[Isoetes]]). The stigmarian system extends leaning from the foundation of the stem as four proximal axes, leading to a hollow rooting structure.<ref name="Hetherington" /> |
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[[File:05July2008 022 SpringhillMinesFm branchingStigmaria.jpg|thumb|left|''Stigmaria'' showing its branching pattern. [[Springhill Mines Formation]] (Pennsylvanian), Nova Scotia, Canada.]] |
[[File:05July2008 022 SpringhillMinesFm branchingStigmaria.jpg|thumb|left|''Stigmaria'' showing its branching pattern. [[Cumberland Group|Springhill Mines Formation]] (Pennsylvanian), Nova Scotia, Canada.]] |
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Along the rhizomorph axes, the appendages are linked to each axis in a circular pattern and would shed during the growth stage, forming the circular scars of ''Stigmaria''. The appendages have a circular layout, and the growth abscission is more distinctive of leaves than present lateral roots. The four proximal axes dichotomize, creating a long underground system ranging up to 15 m (49 ft) in radius, while being up to 40 cm (16 in) long and 0.5–1 cm (0.20–0.39 in) wide. The stigmarian rootlets vary in size and do not dichotomize as they distance away from the central point of the |
Along the rhizomorph axes, the appendages are linked to each axis in a circular pattern and would shed during the growth stage, forming the circular scars of ''Stigmaria''. The lateral appendages have a circular layout, and the growth abscission is more distinctive of leaves than present lateral roots. The four proximal axes dichotomize, creating a long underground system ranging up to 15 m (49 ft) in radius, while being up to 40 cm (16 in) long and 0.5–1 cm (0.20–0.39 in) wide. The stigmarian rootlets vary in size and do not dichotomize as they distance away from the central point of the appendages. In terms of the position, each stigmarian rootlet has a vascular strand monarch which is surrounded by a condensed inner cortex. Externally, this inner cortex consists of a thin outer cortex and hollow middle cortex, and a network enlarges from the inner cortex to the outer cortex.<ref>{{cite journal |last1=Weiss |first1=Frederick Ernest |year=1902 |title=The Vascular branches of Stigmarian rootlets |journal=Annals of Botany |publisher=JSTOR |volume=16 |pages=559–573 |jstor=43235190 |number=63}}</ref> |
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[[File:Joggins_stigmaria_2.jpg|thumb|right|''In situ Stigmaria'' fossil, in the [[Joggins Formation]] (Pennsylvanian), Cumberland Basin, Nova Scotia, Canada]] |
[[File:Joggins_stigmaria_2.jpg|thumb|right|''In situ Stigmaria'' fossil, in the [[Joggins Formation]] (Pennsylvanian), Cumberland Basin, Nova Scotia, Canada]] |
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[[Endarch]] is defined as the primary xylem of ''Stigmaria'', and organized in forked vascular strands encompassed by [[vascular cambium]]. [[Tracheid|Tracheids]] of the secondary xylem are formed in spiral lines and consist of scalariform wall thickenings, while the fimbrils are similar to those in the aerial branches. The tracheids uniform to the stigmarian rhizomorph axes did not form vascular cambium, but dense [[meristem]].<ref>{{cite journal |last1=Rothwell |first1=Gar W. |last2=Pryor |first2=Janelle S. |year=1991 |title=Developmental dynamics of arborescent lycophytes—apical and lateral growth in Stigmaria ficoides |journal=American Journal of Botany |publisher=iley Online Library |volume=78 |pages=1740–1745 |doi=10.1002/j.1537-2197.1991.tb14538.x |number=12}}</ref> |
[[Endarch]] is defined as the primary xylem of ''Stigmaria'', and organized in forked vascular strands encompassed by [[vascular cambium]]. [[Tracheid|Tracheids]] of the secondary xylem are formed in spiral lines and consist of scalariform wall thickenings, while the fimbrils are similar to those in the aerial branches. The tracheids uniform to the stigmarian rhizomorph axes did not form vascular cambium, but dense [[meristem]].<ref>{{cite journal |last1=Rothwell |first1=Gar W. |last2=Pryor |first2=Janelle S. |year=1991 |title=Developmental dynamics of arborescent lycophytes—apical and lateral growth in Stigmaria ficoides |journal=American Journal of Botany |publisher=iley Online Library |volume=78 |pages=1740–1745 |doi=10.1002/j.1537-2197.1991.tb14538.x |number=12}}</ref> |
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=== Development === |
=== Development === |
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[[File:Stigmaria ficoides 04.jpg|thumb|right|''Stigmaria'' impression with visible rootlets connecting from the rhizome.]] |
[[File:Stigmaria ficoides 04.jpg|thumb|right|''Stigmaria'' impression with visible rootlets connecting from the rhizome.]] |
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''Stigmaria'' development is linked to the changes in aerial stems found in typical rhizomic structures seen in present plants. ''Stigmaria's'' features are |
''Stigmaria'' development is linked to the changes in aerial stems found in typical rhizomic structures seen in present plants. ''Stigmaria's'' features are unrelated (in functionality) when linking to the functions of present plant roots and rhizomes. Moreover, the spiral structure of the stigmarian rootlet attachment is distinct to the unsymmetrical adjustment of roots and rhizomes typically seen in modern plants. While there were lateral appendages in ''Stigmaria'', none were found in the root systems of modern plants. However, fungi has [[Mycorrhiza|mycorrhizae]], which are functioned from cortical [[parenchyma]] cells.<ref name="KarlJNiklas"/> |
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[[Image:Stigmaria mcr1.jpg|thumb|left|Bedding plane view of a flattened ''Stigmaria'' preserved atop a shallow-water carbonaceous limestone. [[Joggins]], Nova Scotia, Canada.]] |
[[Image:Stigmaria mcr1.jpg|thumb|left|Bedding plane view of a flattened ''Stigmaria'' preserved atop a shallow-water carbonaceous limestone. [[Joggins]], Nova Scotia, Canada.]] |
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Though vascular bundles in leaves are bilaterally symmetrical including the |
Though vascular bundles in leaves are bilaterally symmetrical including the appendages of ''Stigmaria'' and the monarch vascular bundle, present rhizomes have a radial point of symmetric vascular tissues. Furthermore, within a certain growth stage, foliar abscission (active shedding) of the appendages occurs from the stigmarian axis. Nonetheless, root abscission is relatively unperceived in modern plants. The stigmarian rootlets indicate that there is a similarity in the ''[[Lepidodendrales]]'' aerial structure system, and carry support to its stability features including absorbent organs, branching, and forking of proximal sectors of the axis. The linkage to the ''Lepidodendrales'' vascular plants proposes that the development and changes of the aerial shoot system including the stems existed among stigmarian systems.<ref>{{cite journal |last1=Frankenberg |first1=Julian M. |last2=Eggert |first2=Donald A. |year=1969 |title=Petrified Stigmaria from North America: Part I. Stigmaria ficoides, the underground portions of Lepidodendraceae |journal=Palaeontographica Abteilung B |publisher=Schweizerbart'sche Verlagsbuchhandlung |pages=1–47}}</ref> |
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[[Image:Lycopsid joggins mcr1.JPG|thumb|right|''In situ'' [[lycopsid]] with attached stigmarian system from Joggins, Nova Scotia, Canada.]] |
[[Image:Lycopsid joggins mcr1.JPG|thumb|right|''In situ'' [[lycopsid]] with attached stigmarian system from Joggins, Nova Scotia, Canada.]] |
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Since many lycopsids from the Paleozoic had a height of up to 50 meters, and grew in unsteady engulfed and saturated soil, their stigmarian system was commonly limited to the surface water level. Therefore, it is debatable to how the underground system could handle the plants. Evidence to support their height was compared to the extensive |
Since many lycopsids from the Paleozoic had a height of up to 50 meters, and grew in unsteady engulfed and saturated soil, their stigmarian system was commonly limited to the surface water level. Therefore, it is debatable to how the underground system could handle the plants. Evidence to support their height was compared to the extensive stigmarian system. Thus, it may be that the progression of the rhizomorph axes appeared to have moderate advancement. They may have been preferred to stand upright since arborescent lycopyhtes had bushy branches and only a few secondary xylem. The branches of neighboring lycopsids could interweave and deliver conjunct support. The branch density and development of the wood in present trees typically have a large support to their tree uprooting.<ref name=KarlJNiklas>{{cite book |last1=Niklas |first1=Karl J. |url=https://books.google.com/books?id=l3bRJVMbNMcC&pg=PR9 |title=Plant biomechanics: an engineering approach to plant form and function |publisher=University of Chicago press |year=1992 |isbn=9780226586311}}</ref> |
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==References== |
==References== |
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Revision as of 06:54, 5 January 2024
| Stigmaria | |
|---|---|
| |
| Stigmaria, a fossil lycopsid rhizome | |
Scientific classification 
| |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Lycophytes |
| Class: | Lycopodiopsida |
| Order: | †Lepidodendrales |
| Genus: | †Stigmaria Brongn. |
Stigmaria is a form taxon for common fossils found in Carboniferous rocks.[1] They represent the underground rooting structures of arborescent lycophytes such as Sigillaria and Lepidodendron under the order Lepidodendrales.
Description and morphology
.jpg)
Overview
The Paleozoic swamps had tree-like lycopsids that grew up to 50 meters in height, and these lycopsid plants were anchored by an extensive network of branching underground structures with root-like appendages attached to them.[2] Lycopsids were common plants that lived in low-level swampy areas, and rivers flowing within the coal forests of high, dried land, especially during the Late Carboniferous period or Pennsylvanian age. [3] Analysis of the morphology and anatomy of the stigmarian systems suggests that the axes around the structure were shoot-like, and so they are called rhizomes or rhizomorphs.[4] In general, common species of Stigmaria (Stigmaria ficoides sp.) have been analyzed extensively to provide an understanding of its morphology and histology.[5]
Appendages ("rootlets")
_5_(28407351158).jpg)
The stigmarian systems had rhizomorph axes that presented circular scars around the rhizomorph apices of Stigmaria species, where the root-like appendages were attached to the circular scars. These appendages were branched dichotomously, meaning that there were multiple orders of branching functionality to comprise areas of the stigmarian system. Since the stigmarian systems were root-like, these lateral appendages indicate that these were modified leaves adapted to serve the function of the stigmarian system. Stigmaria had a complex branching structure; therefore, it is comparable to the rhizomes of the extant (living) relative, the quillworts (genus Isoetes). The stigmarian system extends leaning from the foundation of the stem as four proximal axes, leading to a hollow rooting structure.[4]
Along the rhizomorph axes, the appendages are linked to each axis in a circular pattern and would shed during the growth stage, forming the circular scars of Stigmaria. The lateral appendages have a circular layout, and the growth abscission is more distinctive of leaves than present lateral roots. The four proximal axes dichotomize, creating a long underground system ranging up to 15 m (49 ft) in radius, while being up to 40 cm (16 in) long and 0.5–1 cm (0.20–0.39 in) wide. The stigmarian rootlets vary in size and do not dichotomize as they distance away from the central point of the appendages. In terms of the position, each stigmarian rootlet has a vascular strand monarch which is surrounded by a condensed inner cortex. Externally, this inner cortex consists of a thin outer cortex and hollow middle cortex, and a network enlarges from the inner cortex to the outer cortex.[6]
Endarch is defined as the primary xylem of Stigmaria, and organized in forked vascular strands encompassed by vascular cambium. Tracheids of the secondary xylem are formed in spiral lines and consist of scalariform wall thickenings, while the fimbrils are similar to those in the aerial branches. The tracheids uniform to the stigmarian rhizomorph axes did not form vascular cambium, but dense meristem.[7]
Development
Stigmaria development is linked to the changes in aerial stems found in typical rhizomic structures seen in present plants. Stigmaria's features are unrelated (in functionality) when linking to the functions of present plant roots and rhizomes. Moreover, the spiral structure of the stigmarian rootlet attachment is distinct to the unsymmetrical adjustment of roots and rhizomes typically seen in modern plants. While there were lateral appendages in Stigmaria, none were found in the root systems of modern plants. However, fungi has mycorrhizae, which are functioned from cortical parenchyma cells.[8]
Though vascular bundles in leaves are bilaterally symmetrical including the appendages of Stigmaria and the monarch vascular bundle, present rhizomes have a radial point of symmetric vascular tissues. Furthermore, within a certain growth stage, foliar abscission (active shedding) of the appendages occurs from the stigmarian axis. Nonetheless, root abscission is relatively unperceived in modern plants. The stigmarian rootlets indicate that there is a similarity in the Lepidodendrales aerial structure system, and carry support to its stability features including absorbent organs, branching, and forking of proximal sectors of the axis. The linkage to the Lepidodendrales vascular plants proposes that the development and changes of the aerial shoot system including the stems existed among stigmarian systems.[9]
Since many lycopsids from the Paleozoic had a height of up to 50 meters, and grew in unsteady engulfed and saturated soil, their stigmarian system was commonly limited to the surface water level. Therefore, it is debatable to how the underground system could handle the plants. Evidence to support their height was compared to the extensive stigmarian system. Thus, it may be that the progression of the rhizomorph axes appeared to have moderate advancement. They may have been preferred to stand upright since arborescent lycopyhtes had bushy branches and only a few secondary xylem. The branches of neighboring lycopsids could interweave and deliver conjunct support. The branch density and development of the wood in present trees typically have a large support to their tree uprooting.[8]
References
- ^ Rothwell, GW; Erwin, DM (1985). "The rhizophore apex of Paurodendron: implications for homologies among the rooting organs of Lycopsida". American Journal of Botany. 72: 86–98. doi:10.2307/2443571. JSTOR 2443571.
- ^ Cleal, C. J. & Thomas, B. A. (2005). "Palaeozoic tropical rainforests and their effect on global climates: is the past the key to the present?" Geobiology, 3, p. 13-31.
- ^ Christopher J. Cleal; Barry A.Thomas (1994). Plant Fossils of the British Coal Measures. The Palaeontological Association. ISBN 0-901702-53-6.
- ^ a b Hetherington, AJ; Berry, CM; Dolan, Liam (June 14, 2016). "Networks of highly branched stigmarian rootlets developed on the first giant trees" (PDF). PNAS. 113 (24): 6695–6700. doi:10.1073/pnas.1514427113. PMC 4914198. PMID 27226309. Retrieved 15 February 2017.
- ^ Williamson, William Crawford (1887). A monograph on the morphology and histology of Stigmaria ficoides. Vol. 40. Palaeontographical society.
- ^ Weiss, Frederick Ernest (1902). "The Vascular branches of Stigmarian rootlets". Annals of Botany. 16 (63). JSTOR: 559–573. JSTOR 43235190.
- ^ Rothwell, Gar W.; Pryor, Janelle S. (1991). "Developmental dynamics of arborescent lycophytes—apical and lateral growth in Stigmaria ficoides". American Journal of Botany. 78 (12). iley Online Library: 1740–1745. doi:10.1002/j.1537-2197.1991.tb14538.x.
- ^ a b Niklas, Karl J. (1992). Plant biomechanics: an engineering approach to plant form and function. University of Chicago press. ISBN 9780226586311.
- ^ Frankenberg, Julian M.; Eggert, Donald A. (1969). "Petrified Stigmaria from North America: Part I. Stigmaria ficoides, the underground portions of Lepidodendraceae". Palaeontographica Abteilung B. Schweizerbart'sche Verlagsbuchhandlung: 1–47.
