Source: Wikipedia, the free encyclopedia.

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]

Traditional groups:

  • *
  • *
  • *
  • Angiospermae

The embryophytes (

angiosperms (flowering plants). Embryophytes have diplobiontic life cycles.[14]

The embryophytes are informally called "land plants" because they thrive primarily in



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-

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

and keeps the plant rigid.

In common with all groups of multicellular algae they have a life cycle which involves

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

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]


The green algae and land plants form a

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]





Marchantiophytina (Liverworts)


Horneophytopsida [Protracheophytes]


















Lycopodiopsida (Clubmosses, Spikemosses & Quillworts)

Zosterophyllum deciduum















(seed plants)



Non-vascular land plants

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

The non-vascular land plants, namely the

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

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

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

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

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

Large seed of horse chestnut, Aesculus hippocastanum

Seed plants, which first appeared in the fossil record towards the end of the

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]


  1. ^ 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.
  2. .
  3. ^ Barkley, Fred A. Keys to the phyla of organisms. Missoula, Montana. 1939.
  4. ^ Rothmaler, Werner. Über das natürliche System der Organismen. Biologisches Zentralblatt. 67: 242-250. 1948.
  5. ^ 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.
  6. JSTOR 1216134
  7. .
  8. PMID 5762760. Archived from the original
    (PDF) on 2017-11-17. Retrieved 2014-11-28.
  9. .
  10. .
  11. ^ .
  12. .
  13. .
  14. .
  15. ^ .
  16. .
  17. .
  18. .
  19. .
  20. ^ Haeckel, Ernst Heinrich Philipp August (28 September 1894). "Systematische phylogenie". Berlin : Georg Reimer – via Internet Archive.
  21. .
  22. ^ "Phragmoplastin, green algae and the evolution of cytokinesis".[permanent dead link]
  23. ^ "Invasions of the Algae - ScienceNOW - News - Science". Archived from the original on 2013-06-02. Retrieved 2013-03-27.
  24. ^ "All Land Plants Evolved From Single Type of Algae, Scientists Say". Archived from the original on January 26, 2002.
  25. PMID 19273476
  26. . The hemitracheophytes form a monophyletic group that unites the bryophytes and the tracheophytes (or vascular plants)
  27. ^ Becker & Marin 2009, p. 1001
  28. PMID 17030812
  29. .
  30. , retrieved 2019-10-25
  31. ISBN 978-1-919976-39-6. {{cite book}}: |journal= ignored (help
  32. . hemitracheophytes.
  33. .
  34. .
  35. .
  36. ^ , pp. 1582–3
  37. JSTOR 25065646. Archived from the original
    (PDF) on 2008-02-26. Retrieved 2011-01-28.
  38. .
  39. ^ 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.
  40. ^ 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