Embryophyte

Land plants
Temporal range: Mid Ordovician–Present[1][2] (Spores from Dapingian (early Middle Ordovician))
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Streptophyta
Clade: Embryophytes
Engler, 1892[3][4]
Divisions

Traditional groups:

Synonyms

The embryophytes (/ˈɛmbriəˌfts/) are a clade of plants, also known as Embryophyta (/ˌɛmbriˈɒfətə, -ˈftə/) or land plants. They are the most familiar group of photoautotrophs that make up the vegetation on Earth's dry lands and wetlands. Embryophytes have a common ancestor with green algae, having emerged within the Phragmoplastophyta clade of freshwater charophyte green algae as a sister taxon of Charophyceae, Coleochaetophyceae and Zygnematophyceae.[12] Embryophytes consist of the bryophytes and the polysporangiophytes.[13] Living embryophytes include hornworts, liverworts, mosses, lycophytes, ferns, gymnosperms and angiosperms (flowering plants). Embryophytes have diplobiontic life cycles.[14]

The embryophytes are informally called "land plants" because they thrive primarily in terrestrial habitats (despite some members having evolved secondarily to live once again in semiaquatic/aquatic habitats), while the related green algae are primarily aquatic. Embryophytes are complex multicellular eukaryotes with specialized reproductive organs. The name derives from their innovative characteristic of nurturing the young embryo sporophyte during the early stages of its multicellular development within the tissues of the parent gametophyte. With very few exceptions, embryophytes obtain biological energy by photosynthesis, using chlorophyll a and b to harvest the light energy in sunlight for carbon fixation from carbon dioxide and water in order to synthesize carbohydrates while releasing oxygen as a byproduct.

Description

[edit]
Moss, clubmoss, ferns and cycads in a greenhouse

The Embryophytes emerged either a half-billion years ago, at some time in the interval between the mid-Cambrian and early Ordovician, or almost a billion years ago, during the Tonian or Cryogenian,[15] probably from freshwater charophytes, a clade of multicellular green algae similar to extant Klebsormidiophyceae.[16][17][18][19] The emergence of the Embryophytes depleted atmospheric CO2 (a greenhouse gas), leading to global cooling, and thereby precipitating glaciations.[20] Embryophytes are primarily adapted for life on land, although some are secondarily aquatic. Accordingly, they are often called land plants or terrestrial plants.[citation needed]

On a microscopic level, the cells of charophytes are broadly similar to those of chlorophyte green algae, but differ in that in cell division the daughter nuclei are separated by a phragmoplast.[21] They are eukaryotic, with a cell wall composed of cellulose and plastids surrounded by two membranes. The latter include chloroplasts, which conduct photosynthesis and store food in the form of starch, and are characteristically pigmented with chlorophylls a and b, generally giving them a bright green color. Embryophyte cells also generally have an enlarged central vacuole enclosed by a vacuolar membrane or tonoplast, which maintains cell turgor and keeps the plant rigid.

In common with all groups of multicellular algae they have a life cycle which involves alternation of generations. A multicellular haploid generation with a single set of chromosomes – the gametophyte – produces sperm and eggs which fuse and grow into a diploid multicellular generation with twice the number of chromosomes – the sporophyte which produces haploid spores at maturity. The spores divide repeatedly by mitosis and grow into a gametophyte, thus completing the cycle. Embryophytes have two features related to their reproductive cycles which distinguish them from all other plant lineages. Firstly, their gametophytes produce sperm and eggs in multicellular structures (called 'antheridia' and 'archegonia'), and fertilization of the ovum takes place within the archegonium rather than in the external environment. Secondly, the initial stage of development of the fertilized egg (the zygote) into a diploid multicellular sporophyte, takes place within the archegonium where it is both protected and provided with nutrition. This second feature is the origin of the term 'embryophyte' – the fertilized egg develops into a protected embryo, rather than dispersing as a single cell.[17] In the bryophytes the sporophyte remains dependent on the gametophyte, while in all other embryophytes the sporophyte generation is dominant and capable of independent existence.

Embryophytes also differ from algae by having metamers. Metamers are repeated units of development, in which each unit derives from a single cell, but the resulting product tissue or part is largely the same for each cell. The whole organism is thus constructed from similar, repeating parts or metamers. Accordingly, these plants are sometimes termed 'metaphytes' and classified as the group Metaphyta[22] (but Haeckel's definition of Metaphyta places some algae in this group[23]). In all land plants a disc-like structure called a phragmoplast forms where the cell will divide, a trait only found in the land plants in the streptophyte lineage, some species within their relatives Coleochaetales, Charales and Zygnematales, as well as within subaerial species of the algae order Trentepohliales, and appears to be essential in the adaptation towards a terrestrial life style.[24][25][26][27]

Evolution

[edit]

The green algae and land plants form a clade, the Viridiplantae. According to molecular clock estimates, the Viridiplantae split 1,200 million years ago to 725 million years ago into two clades: chlorophytes and streptophytes. The chlorophytes, with around 700 genera, were originally marine algae, although some groups have since spread into fresh water. The streptophyte algae (i.e. excluding the land plants) have around 122 genera; they adapted to fresh water very early in their evolutionary history and have not spread back into marine environments.[citation needed]

Some time during the Ordovician, streptophytes invaded the land and began the evolution of the embryophyte land plants.[28] Present day embryophytes form a clade.[29] Becker and Marin speculate that land plants evolved from streptophytes because living in fresh water pools pre-adapted them to tolerate a range of environmental conditions found on land, such as exposure to rain, tolerance of temperature variation, high levels of ultra-violet light, and seasonal dehydration.[30]

The preponderance of molecular evidence as of 2006 suggested that the groups making up the embryophytes are related as shown in the cladogram below (based on Qiu et al. 2006 with additional names from Crane et al. 2004).[31][32]

Living embryophytes

An updated phylogeny of Embryophytes based on the work by Novíkov & Barabaš-Krasni 2015[33] and Hao and Xue 2013[34] with plant taxon authors from Anderson, Anderson & Cleal 2007[35] and some additional clade names.[36] Puttick et al./Nishiyama et al. are used for the basal clades.[13][37][38]

Paratracheophytes
Lycophytes

Diversity

[edit]

Non-vascular land plants

[edit]
Most bryophytes, such as these mosses, produce stalked sporophytes from which their spores are released.

The non-vascular land plants, namely the mosses (Bryophyta), hornworts (Anthocerotophyta), and liverworts (Marchantiophyta), are relatively small plants, often confined to environments that are humid or at least seasonally moist. They are limited by their reliance on water needed to disperse their gametes; a few are truly aquatic. Most are tropical, but there are many arctic species. They may locally dominate the ground cover in tundra and Arctic–alpine habitats or the epiphyte flora in rain forest habitats.

They are usually studied together because of their many similarities. All three groups share a haploid-dominant (gametophyte) life cycle and unbranched sporophytes (the plant's diploid generation). These traits appear to be common to all early diverging lineages of non-vascular plants on the land. Their life-cycle is strongly dominated by the haploid gametophyte generation. The sporophyte remains small and dependent on the parent gametophyte for its entire brief life. All other living groups of land plants have a life cycle dominated by the diploid sporophyte generation. It is in the diploid sporophyte that vascular tissue develops. In some ways, the term "non-vascular" is a misnomer. Some mosses and liverworts do produce a special type of vascular tissue composed of complex water-conducting cells.[citation needed] However, this tissue differs from that of "vascular" plants in that these water-conducting cells are not lignified.[citation needed] It is unlikely that water-conducting cells in the mosses is homologous with the vascular tissue in "vascular" plants.[citation needed]

Like the vascular plants, they have differentiated stems, and although these are most often no more than a few centimeters tall, they provide mechanical support. Most have leaves, although these typically are one cell thick and lack veins. They lack true roots or any deep anchoring structures. Some species grow a filamentous network of horizontal stems,[clarification needed] but these have a primary function of mechanical attachment rather than extraction of soil nutrients (Palaeos 2008).

Rise of vascular plants

[edit]
Reconstruction of a plant of Rhynia

During the Silurian and Devonian periods (around 440 to 360 million years ago), plants evolved which possessed true vascular tissue, including cells with walls strengthened by lignin (tracheids). Some extinct early plants appear to be between the grade of organization of bryophytes and that of true vascular plants (eutracheophytes). Genera such as Horneophyton have water-conducting tissue more like that of mosses, but a different life-cycle in which the sporophyte is more developed than the gametophyte. Genera such as Rhynia have a similar life-cycle but have simple tracheids and so are a kind of vascular plant.[citation needed] It was assumed that the gametophyte dominant phase seen in bryophytes used to be the ancestral condition in terrestrial plants, and that the sporophyte dominant stage in vascular plants was a derived trait. However, the gametophyte and sporophyte stages were probably equally independent from each other, and that the mosses and vascular plants in that case are both derived, and have evolved in opposite directions.[39]

During the Devonian period, vascular plants diversified and spread to many different land environments. In addition to vascular tissues which transport water throughout the body, tracheophytes have an outer layer or cuticle that resists drying out. The sporophyte is the dominant generation, and in modern species develops leaves, stems and roots, while the gametophyte remains very small.

Lycophytes and euphyllophytes

[edit]
Lycopodiella inundata, a lycophyte

All the vascular plants which disperse through spores were once thought to be related (and were often grouped as 'ferns and allies'). However, recent research suggests that leaves evolved quite separately in two different lineages. The lycophytes or lycopodiophytes – modern clubmosses, spikemosses and quillworts – make up less than 1% of living vascular plants. They have small leaves, often called 'microphylls' or 'lycophylls', which are borne all along the stems in the clubmosses and spikemosses, and which effectively grow from the base, via an intercalary meristem.[40] It is believed that microphylls evolved from outgrowths on stems, such as spines, which later acquired veins (vascular traces).[41]

Although the living lycophytes are all relatively small and inconspicuous plants, more common in the moist tropics than in temperate regions, during the Carboniferous period tree-like lycophytes (such as Lepidodendron) formed huge forests that dominated the landscape.[42]

The euphyllophytes, making up more than 99% of living vascular plant species, have large 'true' leaves (megaphylls), which effectively grow from the sides or the apex, via marginal or apical meristems.[40] One theory is that megaphylls evolved from three-dimensional branching systems by first 'planation' – flattening to produce a two dimensional branched structure – and then 'webbing' – tissue growing out between the flattened branches.[43] Others have questioned whether megaphylls evolved in the same way in different groups.[44]

Ferns and horsetails

[edit]

The ferns and horsetails (the Polypodiophyta) form a clade; they use spores as their main method of dispersal. Traditionally, whisk ferns and horsetails were historically treated as distinct from 'true' ferns.[45] Living whisk ferns and horsetails do not have the large leaves (megaphylls) which would be expected of euphyllophytes. This has probably resulted from reduction, as evidenced by early fossil horsetails, in which the leaves are broad with branching veins.[46]

Ferns are a large and diverse group, with some 12,000 species.[47] A stereotypical fern has broad, much divided leaves, which grow by unrolling.

Seed plants

[edit]
Large seed of horse chestnut, Aesculus hippocastanum

Seed plants, which first appeared in the fossil record towards the end of the Paleozoic era, reproduce using desiccation-resistant capsules called seeds. Starting from a plant which disperses by spores, highly complex changes are needed to produce seeds. The sporophyte has two kinds of spore-forming organs or sporangia. One kind, the megasporangium, produces only a single large spore, a megaspore. This sporangium is surrounded by sheathing layers or integuments which form the seed coat. Within the seed coat, the megaspore develops into a tiny gametophyte, which in turn produces one or more egg cells. Before fertilization, the sporangium and its contents plus its coat is called an ovule; after fertilization a seed. In parallel to these developments, the other kind of sporangium, the microsporangium, produces microspores. A tiny gametophyte develops inside the wall of a microspore, producing a pollen grain. Pollen grains can be physically transferred between plants by the wind or animals, most commonly insects. Pollen grains can also transfer to an ovule of the same plant, either with the same flower or between two flowers of the same plant (self-fertilization). When a pollen grain reaches an ovule, it enters via a microscopic gap in the coat, the micropyle. The tiny gametophyte inside the pollen grain then produces sperm cells which move to the egg cell and fertilize it.[48] Seed plants include two clades with living members, the gymnosperms and the angiosperms or flowering plants. In gymnosperms, the ovules or seeds are not further enclosed. In angiosperms, they are enclosed within the carpel. Angiosperms typically also have other, secondary structures, such as petals, which together form a flower.

Meiosis in sexual land plants provides a direct mechanism for repairing DNA in reproductive tissues.[49] Sexual reproduction appears to be needed for maintaining long-term genomic integrity and only infrequent combinations of extrinsic and intrinsic factors allow for shifts to asexuality.[49]

References

[edit]
  1. ^ Gray, J.; Chaloner, W.G. & Westoll, T.S. (1985), "The Microfossil Record of Early Land Plants: Advances in Understanding of Early Terrestrialization, 1970-1984 [and Discussion]", Philosophical Transactions of the Royal Society B: Biological Sciences, 309 (1138): 167–195, Bibcode:1985RSPTB.309..167G, doi:10.1098/rstb.1985.0077
  2. ^ Rubinstein, C.V.; Gerrienne, P.; De La Puente, G.S.; Astini, R.A. & Steemans, P. (2010), "Early Middle Ordovician evidence for land plants in Argentina (eastern Gondwana)", New Phytologist, 188 (2): 365–9, doi:10.1111/j.1469-8137.2010.03433.x, hdl:11336/55341, PMID 20731783
  3. ^ Engler, A. 1892. Syllabus der Vorlesungen über specielle und medicinisch-pharmaceutische Botanik: Eine Uebersicht über das ganze Pflanzensystem mit Berücksichtigung der Medicinal- und Nutzpflanzen. Berlin: Gebr. Borntraeger.
  4. ^ Pirani, J. R.; Prado, J. (2012). "Embryopsida, a new name for the class of land plants" (PDF). Taxon. 61 (5): 1096–1098. doi:10.1002/tax.615014.
  5. ^ Barkley, Fred A. Keys to the phyla of organisms. Missoula, Montana. 1939.
  6. ^ Rothmaler, Werner. Über das natürliche System der Organismen. Biologisches Zentralblatt. 67: 242-250. 1948.
  7. ^ Barkley, Fred A. "Un esbozo de clasificación de los organismos". Revista de la Facultad Nacional de Agronomia, Universidad de Antioquia, Medellín. 10: 83–103. Archived from the original on 2020-04-21. Retrieved 2014-11-04.
  8. ^ Takhtajan, A (1964). "The taxa of the higher plants above the rank of order" (PDF). Taxon. 13 (5): 160–164. doi:10.2307/1216134. JSTOR 1216134.
  9. ^ Cronquist, A.; Takhtajan, A.; Zimmermann, W. (1966). "On the Higher Taxa of Embryobionta" (PDF). Taxon. 15 (4): 129–134. doi:10.2307/1217531. JSTOR 1217531.
  10. ^ Whittaker, R. H. (1969). "New concepts of kingdoms or organisms" (PDF). Science. 163 (3863): 150–160. Bibcode:1969Sci...163..150W. CiteSeerX 10.1.1.403.5430. doi:10.1126/science.163.3863.150. PMID 5762760. Archived from the original (PDF) on 2017-11-17. Retrieved 2014-11-28.
  11. ^ Margulis, L (1971). "Whittaker's five kingdoms of organisms: minor revisions suggested by considerations of the origin of mitosis". Evolution. 25 (1): 242–245. doi:10.2307/2406516. JSTOR 2406516. PMID 28562945.
  12. ^ Delwiche, Charles F.; Timme, Ruth E. (2011-06-07). "Plants". Current Biology. 21 (11): R417–R422. Bibcode:2011CBio...21.R417D. doi:10.1016/j.cub.2011.04.021. ISSN 0960-9822. PMID 21640897. S2CID 235312105.
  13. ^ a b Puttick, Mark N.; Morris, Jennifer L.; Williams, Tom A.; Cox, Cymon J.; Edwards, Dianne; Kenrick, Paul; Pressel, Silvia; Wellman, Charles H.; Schneider, Harald (2018). "The Interrelationships of Land Plants and the Nature of the Ancestral Embryophyte". Current Biology. 28 (5): 733–745.e2. Bibcode:2018CBio...28E.733P. doi:10.1016/j.cub.2018.01.063. hdl:1983/ad32d4da-6cb3-4ed6-add2-2415f81b46da. PMID 29456145.
  14. ^ Gerrienne, Philippe; Gonez, Paul (January 2011). "Early evolution of life cycles in embryophytes: A focus on the fossil evidence of gametophyte/sporophyte size and morphological complexity". Journal of Systematics and Evolution. 49 (1): 1–16. doi:10.1111/j.1759-6831.2010.00096.x. hdl:2268/101745. S2CID 29795245.
  15. ^ Su, Danyan; Yang, Lingxiao; Shi, Xuan; Ma, Xiaoya; Zhou, Xiaofan; Hedges, S Blair; Zhong, Bojian (2021-07-29). Battistuzzi, Fabia Ursula (ed.). "Large-Scale Phylogenomic Analyses Reveal the Monophyly of Bryophytes and Neoproterozoic Origin of Land Plants". Molecular Biology and Evolution. 38 (8): 3332–3344. doi:10.1093/molbev/msab106. ISSN 1537-1719. PMC 8321542. PMID 33871608.
  16. ^ Frangedakis, Eftychios; Shimamura, Masaki; Villarreal, Juan Carlos; Li, Fay-Wei; Tomaselli, Marta; Waller, Manuel; Sakakibara, Keiko; Renzaglia, Karen S.; Szövényi, Péter (January 2021). "The hornworts: morphology, evolution and development". New Phytologist. 229 (2): 735–754. doi:10.1111/nph.16874. PMC 7881058. PMID 32790880.
  17. ^ a b Niklas, K.J.; Kutschera, U. (2010), "The evolution of the land plant life cycle", New Phytologist, 185 (1): 27–41, doi:10.1111/j.1469-8137.2009.03054.x, PMID 19863728.
  18. ^ de Vries, J; Archibald, JM (March 2018). "Plant evolution: landmarks on the path to terrestrial life". The New Phytologist. 217 (4): 1428–1434. doi:10.1111/nph.14975. PMID 29318635.
  19. ^ Del-Bem, Luiz-Eduardo (2018-05-31). "Xyloglucan evolution and the terrestrialization of green plants". New Phytologist. 219 (4): 1150–1153. doi:10.1111/nph.15191. hdl:1843/36860. ISSN 0028-646X. PMID 29851097.
  20. ^ Donoghue, Philip C.J.; Harrison, C. Jill; Paps, Jordi; Schneider, Harald (October 2021). "The evolutionary emergence of land plants". Current Biology. 31 (19): R1281–R1298. Bibcode:2021CBio...31R1281D. doi:10.1016/j.cub.2021.07.038. hdl:1983/662d176e-fcf4-40bf-aa8c-5694a86bd41d. PMID 34637740. S2CID 238588736.
  21. ^ Pickett-Heaps, J. (1976). "Cell division in eucaryotic algae". BioScience. 26 (7): 445–450. doi:10.2307/1297481. JSTOR 1297481.
  22. ^ Mayr, E. (1990), "A natural system of organisms", Nature, 348 (6301): 491, Bibcode:1990Natur.348..491M, doi:10.1038/348491a0, S2CID 13454722
  23. ^ Haeckel, Ernst Heinrich Philipp August (28 September 1894). "Systematische phylogenie". Berlin : Georg Reimer – via Internet Archive.
  24. ^ John, Whitfield (19 February 2001). "Land plants divided and ruled". Nature News: conference010222–8. doi:10.1038/conference010222-8.
  25. ^ "Phragmoplastin, green algae and the evolution of cytokinesis".[permanent dead link]
  26. ^ "Invasions of the Algae - ScienceNOW - News - Science". Archived from the original on 2013-06-02. Retrieved 2013-03-27.
  27. ^ "All Land Plants Evolved From Single Type of Algae, Scientists Say". Archived from the original on January 26, 2002.
  28. ^ Becker, B. & Marin, B. (2009), "Streptophyte algae and the origin of embryophytes", Annals of Botany, 103 (7): 999–1004, doi:10.1093/aob/mcp044, PMC 2707909, PMID 19273476
  29. ^ Lecointre, Guillaume; Guyader, Hervé Le (August 28, 2006). The Tree of Life: A Phylogenetic Classification. Harvard University Press. p. 175. ISBN 978-0-6740-2183-9. The hemitracheophytes form a monophyletic group that unites the bryophytes and the tracheophytes (or vascular plants)
  30. ^ Becker & Marin 2009, p. 1001
  31. ^ Qiu, Y.L.; Li, L.; Wang, B.; Chen, Z.; et al. (2006), "The deepest divergences in land plants inferred from phylogenomic evidence", Proceedings of the National Academy of Sciences, 103 (42): 15511–6, Bibcode:2006PNAS..10315511Q, doi:10.1073/pnas.0603335103, PMC 1622854, PMID 17030812
  32. ^ Crane, P.R.; Herendeen, P. & Friis, E.M. (2004), "Fossils and plant phylogeny", American Journal of Botany, 91 (10): 1683–99, doi:10.3732/ajb.91.10.1683, PMID 21652317
  33. ^ Novíkov & Barabaš-Krasni (2015). Modern plant systematics. Liga-Pres. p. 685. doi:10.13140/RG.2.1.4745.6164. ISBN 978-966-397-276-3.
  34. ^ Hao, Shougang & Xue, Jinzhuang (2013), The early Devonian Posongchong flora of Yunnan: a contribution to an understanding of the evolution and early diversification of vascular plants, Beijing: Science Press, p. 366, ISBN 978-7-03-036616-0, retrieved 2019-10-25
  35. ^ Anderson, Anderson & Cleal (2007). Brief history of the gymnosperms: classification, biodiversity, phytogeography and ecology. Vol. 20. SANBI. p. 280. ISBN 978-1-919976-39-6. {{cite book}}: |journal= ignored (help)
  36. ^ Lecointre, Guillaume; Guyader, Hervé Le (2006). The Tree of Life: A Phylogenetic Classification. Harvard University Press. p. 175. ISBN 9780674021839. hemitracheophytes.
  37. ^ Nishiyama, Tomoaki; Wolf, Paul G.; Kugita, Masanori; Sinclair, Robert B.; Sugita, Mamoru; Sugiura, Chika; Wakasugi, Tatsuya; Yamada, Kyoji; Yoshinaga, Koichi (2004-10-01). "Chloroplast Phylogeny Indicates that Bryophytes Are Monophyletic". Molecular Biology and Evolution. 21 (10): 1813–1819. doi:10.1093/molbev/msh203. ISSN 0737-4038. PMID 15240838.
  38. ^ Gitzendanner, Matthew A.; Soltis, Pamela S.; Wong, Gane K.-S.; Ruhfel, Brad R.; Soltis, Douglas E. (2018). "Plastid phylogenomic analysis of green plants: A billion years of evolutionary history". American Journal of Botany. 105 (3): 291–301. doi:10.1002/ajb2.1048. ISSN 0002-9122. PMID 29603143.
  39. ^ Štorch, Petr; Žárský, Viktor; Bek, Jiří; Kvaček, Jiří; Libertín, Milan (May 28, 2018). "Sporophytes of polysporangiate land plants from the early Silurian period may have been photosynthetically autonomous". Nature Plants. 4 (5): 269–271. doi:10.1038/s41477-018-0140-y. PMID 29725100. S2CID 19151297.
  40. ^ a b Pryer, K.M.; Schuettpelz, E.; Wolf, P.G.; Schneider, H.; Smith, A.R. & Cranfill, R. (2004), "Phylogeny and evolution of ferns (monilophytes) with a focus on the early leptosporangiate divergences", American Journal of Botany, 91 (10): 1582–98, doi:10.3732/ajb.91.10.1582, PMID 21652310, pp. 1582–3
  41. ^ Boyce, C.K. (2005), "The evolutionary history of roots and leaves", in Holbrook, N.M. & Zwieniecki, M.A. (eds.), Vascular Transport in Plants, Burlington: Academic Press, pp. 479–499, doi:10.1016/B978-012088457-5/50025-3, ISBN 978-0-12-088457-5
  42. ^ Sahney, S.; Benton, M.J. & Falcon-Lang, H.J. (2010), "Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica", Geology, 38 (12): 1079–1082, Bibcode:2010Geo....38.1079S, doi:10.1130/G31182.1
  43. ^ Beerling, D.J. & Fleming, A.J. (2007), "Zimmermann's telome theory of megaphyll leaf evolution: a molecular and cellular critique", Current Opinion in Plant Biology, 10 (1): 4–12, Bibcode:2007COPB...10....4B, doi:10.1016/j.pbi.2006.11.006, PMID 17141552
  44. ^ Tomescu, A. (2009), "Megaphylls, microphylls and the evolution of leaf development", Trends in Plant Science, 14 (1): 5–12, doi:10.1016/j.tplants.2008.10.008, PMID 19070531
  45. ^ Smith, A.R.; Pryer, K.M.; Schuettpelz, E.; Korall, P.; Schneider, H. & Wolf, P.G. (2006). "A classification for extant ferns" (PDF). Taxon. 55 (3): 705–731. doi:10.2307/25065646. JSTOR 25065646. Archived from the original (PDF) on 2008-02-26. Retrieved 2011-01-28.
  46. ^ Rutishauser, R. (1999). "Polymerous Leaf Whorls in Vascular Plants: Developmental Morphology and Fuzziness of Organ Identities". International Journal of Plant Sciences. 160 (6): 81–103. doi:10.1086/314221. PMID 10572024. S2CID 4658142.
  47. ^ Chapman, Arthur D. (2009). "Numbers of Living Species in Australia and the World. Report for the Australian Biological Resources Study". Canberra, Australia. Retrieved 2011-03-11.
  48. ^ Taylor, T.N.; Taylor, E.L.; Krings, M. (2009), Paleobotany, The Biology and Evolution of Fossil Plants (2nd ed.), Amsterdam; Boston: Academic Press, pp. 508ff, ISBN 978-0-12-373972-8
  49. ^ a b Hörandl E. Apomixis and the paradox of sex in plants. Ann Bot. 2024 Mar 18:mcae044. doi: 10.1093/aob/mcae044. Epub ahead of print. PMID 38497809

Bibliography

[edit]
  • Raven, P.H.; Evert, R.F. & Eichhorn, S.E. (2005), Biology of Plants (7th ed.), New York: W.H. Freeman, ISBN 978-0-7167-1007-3
  • Stewart, W.N. & Rothwell, G.W. (1993), Paleobotany and the Evolution of Plants (2nd ed.), Cambridge: Cambridge University Press, ISBN 978-0-521-38294-6
  • Taylor, T.N.; Taylor, E.L. & Krings, M. (2009), Paleobotany, The Biology and Evolution of Fossil Plants (2nd ed.), Amsterdam; Boston: Academic Press, ISBN 978-0-12-373972-8