Hornwort

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Hornwort
Temporal range: 90–0  Ma
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Upper Cretaceous (but see text) to present
Phaeoceros laevis.jpg
Phaeoceros laevis (L.) Prosk.
Scientific classification OOjs UI icon edit-ltr.svg
Kingdom: Plantae
Clade: Embryophytes
Division: Anthocerotophyta
Stotler & Stotl.-Crand., 1977 [1]
Classes and orders
Leiosporocerotopsida
Anthocerotopsida

see Classification .

Synonyms

Anthocerotae

Hornworts are a group of non-vascular Embryophytes (land plants) constituting the division Anthocerotophyta ( /ˌænθoʊˌsɛrəˈtɒfətə,-təˈfaɪtə/ ). The common name refers to the elongated horn-like structure, which is the sporophyte. As in mosses and liverworts, hornworts have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information; the flattened, green plant body of a hornwort is the gametophyte stage of the plant.

Hornworts may be found worldwide, though they tend to grow only in places that are damp or humid. Some species grow in large numbers as tiny weeds in the soil of gardens and cultivated fields. Large tropical and sub-tropical species of Dendroceros may be found growing on the bark of trees.

The total number of species is still uncertain. While there are more than 300 published species names, the actual number could be as low as 100-150 species. [2]

Description

Like all bryophytes, the dominant life phase of a hornwort is the haploid gametophyte. This stage usually grows as a thin rosette or ribbon-like thallus between one and five centimeters in diameter. Hornworts have lost two plastid division-associated genes, ARC3 and FtsZ2, and have just a single chloroplast per cell (monoplastidy), with the exception of the genus Megaceros and some species in the genera Nothoceros and Anthoceros , which have more than one chloroplast per cell (polyplastidy). In the polyplastidic species, and also some of the monoplastidic species, a cellular structure called a pyrenoid is absent. [3] [4] The pyrenoid, which is both a food storing organ and enables a more efficient photosynthesis, has evolved independently five to six times in hornworts and is present in half of the roughly 200 species. [5] It is formed by the fusion of the chloroplast with other organelles and is comprised predominantly of RuBisCO, the key enzyme in carbon fixation. By using inorganic carbon transporters and carbonic anhydrases, up to a 50-fold increase in CO2 levels can be achieved. [6] This particular feature is very unusual in land plants, unique to hornworts, but is common among algae. [7] [8] They are also the only group of land plants where flavonoids are completely absent. [9]

Many hornworts develop internal mucilage-filled cavities or canals when groups of cells break down. These cavities secrete hormogonium-inducing factors (HIF) that stimulate nearby, free-living photosynthetic cyanobacteria, especially species of Nostoc , to invade and colonize these cavities. [10] Such colonies of bacteria growing inside the thallus give the hornwort a distinctive blue-green color. Symbiotic cyanobacteria have not been reported in Megaceros or Folioceros . [11] There may also be small slime pores on the underside of the thallus. These pores superficially resemble the stomata of other plants.

The horn-shaped sporophyte grows from an archegonium embedded deep in the gametophyte. The growth of the hornwort sporophyte happens from a persistent basal meristem, in contrast to the sporophyte of moss (apical growth) and liverworts (intercalary growth). [12] Unlike liverworts, hornworts have true stomata on their sporophyte as most mosses do. The exceptions are the species Folioceros incurvus, the genus Notothylas and the three closely related genera Megaceros , Nothoceros and Dendroceros , which do not have stomata. [13] [14] Notothylas also differ from other hornworts in having a reduced sporophyte only a few millimeters tall. The sporophyte in hornworts is unique among bryophytes in being long-lived with a persistent photosynthetic capacity. [15] The sporophyte lacks an apical meristem, an auxin-sensitive point of divergence with other land plants some time in the Late Silurian/Early Devonian. [16] [17]

When the sporophyte is mature, it has a multicellular outer layer, a central rod-like columella running up the center, and a layer of tissue in between that produces spores and pseudo-elaters. The pseudo-elaters are multi-cellular, unlike the elaters of liverworts. They have helical thickenings that change shape in response to drying out; they twist and thereby help to disperse the spores. Hornwort spores are relatively large for bryophytes, measuring between 30 and 80 µm in diameter or more. The spores are polar, usually with a distinctive Y-shaped tri-radiate ridge on the proximal surface, and with a distal surface ornamented with bumps or spines.

Life cycle

The life of a hornwort starts from a haploid spore. The spores can be yellow, brown or green. Yellow and brown spores have a thicker wall and contain oils that both protect against desiccation and function as a nutrient storage, allowing them to survive for years. The species Folioceros fuciformis and the genera Megaceros, Nothoceros and Dendroceros have short-lived spores with thin and colorless walls that appear green due to the presence of a chloroplast. [18] [19] In most species, there is a single cell inside the spore, and a slender extension of this cell called the germ tube germinates from the proximal side of the spore. [20] The tip of the germ tube divides to form an octant (solid geometry) of cells, and the first rhizoid grows as an extension of the original germ cell.[ clarification needed ] The tip continues to divide new cells, which produces a thalloid protonema. By contrast, species of the family Dendrocerotaceae may begin dividing within the spore, becoming multicellular and even photosynthetic before the spore germinates. [20] In either case, the protonema is a transitory stage in the life of a hornwort.

Life cycle of a typical hornwort Phaeoceros. Click on the image to enlarge. Hornwort life cycle.svg
Life cycle of a typical hornwort Phaeoceros. Click on the image to enlarge.

From the protonema grows the adult gametophyte, which is the persistent and independent stage in the life cycle. This stage usually grows as a thin rosette or ribbon-like thallus between one and five centimeters in diameter, and several layers of cells in thickness. It is green or yellow-green from the chlorophyll in its cells, or bluish-green when colonies of cyanobacteria grow inside the plant.

When the gametophyte has grown to its adult size, it produces the sex organs of the hornwort. Most plants are monoecious, with both sex organs on the same plant, but some plants (even within the same species) are dioecious, with separate male and female gametophytes. The female organs are known as archegonia (singular archegonium) and the male organs are known as antheridia (singular antheridium). Both kinds of organs develop just below the surface of the plant and are only later exposed by disintegration of the overlying cells.

The biflagellate sperm must swim from the antheridia, or else be splashed to the archegonia. When this happens, the sperm and egg cell fuse to form a zygote, the cell from which the sporophyte stage of the life cycle will develop. Unlike all other bryophytes, the first cell division of the zygote is longitudinal. Further divisions produce three basic regions of the sporophyte.

At the bottom of the sporophyte (closest to the interior of the gametophyte), is a foot. This is a globular group of cells that receives nutrients from the parent gametophyte, on which the sporophyte will spend its entire existence. In the middle of the sporophyte (just above the foot), is a meristem that will continue to divide and produce new cells for the third region. This third region is the capsule. Both the central and surface cells of the capsule are sterile, but between them is a layer of cells that will divide to produce pseudo-elaters and spores. These are released from the capsule when it splits lengthwise from the tip.

Evolutionary history

While the fossil record of crown group hornworts only begins in the upper Cretaceous, the lower Devonian Horneophyton may represent a stem group to the clade, as it possesses a sporangium with central columella not attached at the roof. [21] However, the same form of columella is also characteristic of basal moss groups, such as the Sphagnopsida and Andreaeopsida, and has been interpreted as a character common to all early land plants with stomata. [22] The divergence between hornworts and Setaphyta (mosses and liverworts) is estimated to have occurred 479–450 million years ago, [23] and the last common ancestor of present-day hornworts lived in middle Permian about 275 million years ago. [24] Chromosome-scale genome sequencing of three hornwort species corroborates that stomata evolved only once during land plant evolution. It also shows that the three groups of bryophytes share a common ancestor that branched off from the other landplants early in evolution, and that liverworts and mosses are more closely related to each other than to hornworts. [25] Unlike other land plants, the hornwort genome has the low-CO2 inducible B gene (LCIB), which is also found in some species of algae. Because the diffusion rate of carbon dioxide is 10,000-fold higher in air than in water, aquatic algae require a mechanism to concentrate CO2 in chloroplasts so as to allow the photosynthetic RuBisCo protein to function efficiently. LCIB is one component of this CO2-concentrating mechanism. [26]

Classification

The hornwort Dendroceros crispus growing on the bark of a tree. Dendroceros.jpg
The hornwort Dendroceros crispus growing on the bark of a tree.

Hornworts were traditionally considered a class within the division Bryophyta (bryophytes). Later on, the bryophytes were considered paraphyletic, and hence the hornworts were given their own division, Anthocerotophyta (sometimes misspelled Anthocerophyta). However, the most recent phylogenetic evidence leans strongly towards bryophyte monophyly, [27] and it has been proposed that hornworts are de-ranked to the original class Anthocerotopsida. [28]

Traditionally, there was a single class of hornworts, called Anthocerotopsida, or older Anthocerotae. More recently, a second class Leiosporocertotopsida has been segregated for the singularly unusual species Leiosporoceros dussii . All other hornworts remain in the class Anthocerotopsida. These two classes are divided further into five orders, each containing a single family.

Among land plants, hornworts are one of the earliest-diverging lineages of the early land plant ancestors; [25] cladistic analysis implies that the group originated prior to the Devonian, around the same time as the mosses and liverworts. There are about 200 species known, but new species are still being discovered. The number and names of genera are a current matter of investigation, and several competing classification schemes have been published since 1988.

Structural features that have been used in the classification of hornworts include: the anatomy of chloroplasts and their numbers within cells, the presence of a pyrenoid, the numbers of antheridia within androecia, and the arrangement of jacket cells of the antheridia. [29]

Phylogeny

Recent studies of molecular, ultrastructural, and morphological data have yielded a new classification of hornworts. [30] [31]

Class Leiosporocerotopsida

Leiosporocerotales

Class Anthocerotopsida

Anthocerotales
Notothyladales
Phymatocerotales
Dendrocerotales
Leiosporocerotopsida
Leiosporocerotales
Leiosporocerotaceae

Leiosporoceros

Anthocerotopsida
The current phylogeny and composition of the Anthocerotophyta. [30] [32] [33] [34]

See also

Related Research Articles

<span class="mw-page-title-main">Gametophyte</span> Haploid stage in the life cycle of plants and algae

A gametophyte is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes.

<span class="mw-page-title-main">Alternation of generations</span> Reproductive cycle of plants and algae

Alternation of generations is the predominant type of life cycle in plants and algae. In plants both phases are multicellular: the haploid sexual phase – the gametophyte – alternates with a diploid asexual phase – the sporophyte.

<span class="mw-page-title-main">Moss</span> Division of non-vascular land plants

Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophytasensu stricto. Bryophyta may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hornworts. Mosses typically form dense green clumps or mats, often in damp or shady locations. The individual plants are usually composed of simple leaves that are generally only one cell thick, attached to a stem that may be branched or unbranched and has only a limited role in conducting water and nutrients. Although some species have conducting tissues, these are generally poorly developed and structurally different from similar tissue found in vascular plants. Mosses do not have seeds and after fertilisation develop sporophytes with unbranched stalks topped with single capsules containing spores. They are typically 0.2–10 cm (0.1–3.9 in) tall, though some species are much larger. Dawsonia, the tallest moss in the world, can grow to 50 cm (20 in) in height. There are approximately 12,000 species.

<span class="mw-page-title-main">Bryophyte</span> Terrestrial plants that lack vascular tissue

Bryophytes are a group of land plants, sometimes treated as a taxonomic division, that contains three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. In the strict sense, Bryophyta consists of the mosses only. Bryophytes are characteristically limited in size and prefer moist habitats although they can survive in drier environments. The bryophytes consist of about 20,000 plant species. Bryophytes produce enclosed reproductive structures, but they do not produce flowers or seeds. They reproduce sexually by spores and asexually by fragmentation or the production of gemmae. Though bryophytes were considered a paraphyletic group in recent years, almost all of the most recent phylogenetic evidence supports the monophyly of this group, as originally classified by Wilhelm Schimper in 1879. The term bryophyte comes from Ancient Greek βρύον (brúon) 'tree moss, liverwort', and φυτόν (phutón) 'plant'.

<span class="mw-page-title-main">Embryophyte</span> Subclade of green plants, also known as land plants

The embryophytes are a clade of plants, also known as Embryophyta 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. Embryophytes consist of the bryophytes and the polysporangiophytes. Living embryophytes include hornworts, liverworts, mosses, lycophytes, ferns, gymnosperms and angiosperms. Embryophytes have diplobiontic life cycles.

<span class="mw-page-title-main">Marchantiophyta</span> Botanical division of non-vascular land plants

The Marchantiophyta are a division of non-vascular land plants commonly referred to as hepatics or liverworts. Like mosses and hornworts, they have a gametophyte-dominant life cycle, in which cells of the plant carry only a single set of genetic information.

<span class="mw-page-title-main">Sporophyte</span> Diploid multicellular stage in the life cycle of a plant or alga

A sporophyte is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.

<span class="mw-page-title-main">Non-vascular plant</span> Plant without a vascular system

Non-vascular plants are plants without a vascular system consisting of xylem and phloem. Instead, they may possess simpler tissues that have specialized functions for the internal transport of water.

<span class="mw-page-title-main">Antheridium</span> Part of a plant producing and containing male gametes

An antheridium is a haploid structure or organ producing and containing male gametes. The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. Androecium is also the collective term for the stamens of flowering plants.

<i>Takakia</i> Genus of mosses

Takakia is a genus of two species of mosses known from western North America and central and eastern Asia. The genus is placed as a separate family, order and class among the mosses. It has had a history of uncertain placement, but the discovery of sporophytes clearly of the moss-type firmly supports placement with the mosses.

<i>Dendroceros</i> Genus of hornworts

Dendroceros is a genus of hornworts in the family Dendrocerotaceae. The genus contains about 51 species native to tropical and sub-tropical regions of the world.

<i>Conocephalum</i> Genus of plants

Conocephalum is a genus of complex thalloid liverworts in the order Marchantiales and is the only extant genus in the family Conocephalaceae. Some species of Conocephalum are assigned to the Conocephalum conicum complex, which includes several cryptic species. Conocephalum species are large liverworts with distinct patterns on the upper thallus, giving the appearance of snakeskin. The species Conocephalum conicum is named for its cone-shaped reproductive structures, called archegoniophores. Common names include snakeskin liverwort, great scented liverwort and cat-tongue liverwort.

<i>Megaceros</i> Genus of hornworts

Megaceros is a genus of hornworts in the family Dendrocerotaceae. The genus is found in the Old World tropics of east Asia and Australia. Its name means 'big horn', and refers both to the exceptionally large size of the gametophyte thallus and to the large, horn-shaped sporophyte that the plants produce. Many species have a branching thallus that is more than two centimeters wide. The gametophytes are monoicous.

Notothylas is a genus of hornworts in the family Notothyladaceae. The genus is found globally, but is usually overlooked. It is the smallest of all the hornworts, with a yellow-green gametophyte thallus that is seldom more than a centimeter in diameter, and usually much smaller.

Monoicy is a sexual system in haploid plants where both sperm and eggs are produced on the same gametophyte, in contrast with dioicy, where each gametophyte produces only sperm or eggs but never both. Both monoicous and dioicous gametophytes produce gametes in gametangia by mitosis rather than meiosis, so that sperm and eggs are genetically identical with their parent gametophyte.

<i>Buxbaumia</i> Genus of mosses

Buxbaumia is a genus of twelve species of moss (Bryophyta). It was first named in 1742 by Albrecht von Haller and later brought into modern botanical nomenclature in 1801 by Johann Hedwig to commemorate Johann Christian Buxbaum, a German physician and botanist who discovered the moss in 1712 at the mouth of the Volga River. The moss is microscopic for most of its existence, and plants are noticeable only after they begin to produce their reproductive structures. The asymmetrical spore capsule has a distinctive shape and structure, some features of which appear to be transitional from those in primitive mosses to most modern mosses.

<i>Cavicularia</i> Genus of liverworts

Cavicularia densa is the only species in the liverwort genus Cavicularia. The species was first described in 1897 by Franz Stephani, and is endemic to Japan, where it grows on fine moist soil.

<i>Takakia ceratophylla</i> Species of moss

Takakia ceratophylla is one of the two species of toothless mosses in the genus Takakia, under the Takakiaceae family. This species was first described by William Mitten in 1861. Takakia ceratophylla is vulnerable and threatened by habitat loss due to human activities.

Leiosporoceros dussii is the only species in the hornwort genus Leiosporoceros. The species is placed in a separate family, order, and class for being "genetically and morphologically distinct from all other hornwort lineages." Cladistic analysis of genetic data supports a position at the very base of the hornwort clade. Physical characteristics that distinguish the group include unusually small spores that are monolete and unornamented. Additionally, there are unique strands of Nostoc (cyanobacteria) that grow inside the plant parallel with its direction of growth. Unlike other hornworts with symbiotic cyanobacteria that enters through mucilage clefts, the mucilage clefts in Leiosporoceros is only present in young plants and then closes permanently once the cyanobacterial colonies have been established. Also mycorrhiza and pyrenoids are absent. Male plants have been found in Panama.

<i>Aneura mirabilis</i> Species of liverwort

Aneura mirabilis is a parasitic species of liverworts in the family Aneuraceae. It was first described in 1933, as Cryptothallus mirabilis. Plants of this species are white as a result of lacking chlorophyll, and their plastids do not differentiate into chloroplasts.

References

  1. ↑ Stotler, Raymond E.; Barbara J. Candall-Stotler (1977). "A checklist of the liverworts and hornworts of North America". The Bryologist. 80 (3). American Bryological and Lichenological Society: 405–428. doi:10.2307/3242017. JSTOR   3242017.
  2. ↑ Lepp, Heino (12 September 2012). "What is a hornwort?". Australian Bryophytes. Australian National Botanic Gardens.
  3. ↑ Loss of plastid developmental genes coincides with a reversion to monoplastidy in hornworts - bioRxiv
  4. ↑ Hornworts: An Overlooked Window into Carbon-Concentrating Mechanisms - Villarreal Lab
  5. ↑ Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years
  6. ↑ Meyer, Moritz T.; McCormick, Alistair J.; Griffiths, Howard (2016). "Will an algal CO2-concentrating mechanism work in higher plants?". Current Opinion in Plant Biology. 31: 181–188. doi:10.1016/j.pbi.2016.04.009. PMID   27194106.
  7. ↑ Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years - PNAS
  8. ↑ BTI researchers unlocking hornworts' secrets | EurekAlert! Science News
  9. ↑ The Evolution of Flavonoid Biosynthesis: A Bryophyte Perspective
  10. ↑ Meeks, JC (1998). "Symbiosis between nitrogen-fixing cyanobacteria and plants". BioScience. 48 (4): 266–276. doi: 10.2307/1313353 . JSTOR   1313353.
  11. ↑ Stress Biology of Cyanobacteria: Molecular Mechanisms to Cellular Responses
  12. ↑ How was apical growth regulated in the ancestral land plant? Insights from the development of non-seed plants
  13. ↑ Hornwort Stomata: Architecture and Fate Shared with 400-Million-Year-Old Fossil Plants without Leaves
  14. ↑ Classification of the Phylum Anthocerotophyta Stotl. & Crand.-Stotl.
  15. ↑ The deepest divergences in land plants inferred from phylogenomic evidence - PNAS
  16. ↑ Cooke, Todd J; Poli, DorothyBelle; Cohen, Jerry D (2003). "Did auxin play a crucial role in the evolution of novel body plans during the Late Silurian-Early Devonian radiation of land plants?". The Evolution of Plant Physiology. Elsevier. pp. 85–107. doi:10.1016/b978-012339552-8/50006-8. ISBN   978-0-12-339552-8.
  17. ↑ Friedman, William E.; Moore, Richard C.; Purugganan, Michael D. (2004). "The evolution of plant development". American Journal of Botany . 91 (10). Botanical Society of America (Wiley): 1726–1741. doi: 10.3732/ajb.91.10.1726 . ISSN   0002-9122. PMID   21652320.
  18. ↑ Bryophyte Biology
  19. ↑ NEW CLASSIFICATION OF ANTHOCEROTAE - J-Stage
  20. 1 2 Chopra, R. N.; Kumra, P. K. (1988). Biology of Bryophytes. New York: John Wiley & Sons. ISBN   0-470-21359-0.
  21. ↑ Qiu, Y.L.; Li, L.; Wang, B.; Chen, Z.; Knoop, V.; Groth-malonek, M.; Dombrovska, O.; Lee, J.; Kent, L.; Rest, J.; 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.
  22. ↑ Kenrick, Paul; Peter R. Crane (1997). The Origin and Early Diversification of Land Plants: A Cladistic Study. Washington, D. C.: Smithsonian Institution Press. pp. 55–56. ISBN   1-56098-730-8.
  23. ↑ Harris, Brogan J.; Clark, James W.; Schrempf, Dominik; Szöllősi, Gergely J.; Donoghue, Philip C. J.; Hetherington, Alistair M.; Williams, Tom A. (2022). "Divergent evolutionary trajectories of bryophytes and tracheophytes from a complex common ancestor of land plants". Nature Ecology & Evolution. 6 (11): 1634–1643. doi:10.1038/s41559-022-01885-x. PMC   9630106 . PMID   36175544.
  24. ↑ Zhang, Jian; Fu, Xin-Xing; Li, Rui-Qi; Zhao, Xiang; Liu, Yang; Li, Ming-He; Zwaenepoel, Arthur; Ma, Hong; Goffinet, Bernard; Guan, Yan-Long; Xue, Jia-Yu; Liao, Yi-Ying; Wang, Qing-Feng; Wang, Qing-Hua; Wang, Jie-Yu; Zhang, Guo-Qiang; Wang, Zhi-Wen; Jia, Yu; Wang, Mei-Zhi; Dong, Shan-Shan; Yang, Jian-Fen; Jiao, Yuan-Nian; Guo, Ya-Long; Kong, Hong-Zhi; Lu, An-Ming; Yang, Huan-Ming; Zhang, Shou-Zhou; Van De Peer, Yves; Liu, Zhong-Jian; Chen, Zhi-Duan (2020). "The hornwort genome and early land plant evolution". Nature Plants. 6 (2): 107–118. doi:10.1038/s41477-019-0588-4. PMC   7027989 . PMID   32042158.
  25. 1 2 Li, F-W.; Nishiyama, T.; Waller, M.; et, al. (2020). "Anthoceros genomes illuminate the origin of land plants and the unique biology of hornworts". Nature Plants. 6 (3): 259–272. doi: 10.1038/s41477-020-0618-2 . PMC   8075897 . PMID   32170292.
  26. ↑ 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.
  27. ↑ Su, Danyan; et al. (2021). "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. PMC   8321542 . PMID   33871608.
  28. ↑ de Sousa, Filipe; et al. (2019). "Nuclear protein phylogenies support the monophyly of the three bryophyte groups (Bryophyta Schimp.)". New Phytologist. 222 (1): 565–575. doi:10.1111/nph.15587. hdl: 1983/0b471d7e-ce54-4681-b791-1da305d9e53b . PMID   30411803. S2CID   53240320.
  29. ↑ D. Christine Cargill; Karen S. Renzaglia; Juan Carlos Villarreal; R. Joel Duff (2005), "Generic concepts within hornworts: Historical review, contemporary insights and future directions", Australian Systematic Botany, 18: 7–16, doi:10.1071/sb04012
  30. 1 2 Duff, R. Joel; Juan Carlos Villarreal; D. Christine Cargill; Karen S. Renzaglia (2007). "Progress and challenges toward a phylogeny and classification of the hornworts". The Bryologist. 110 (2): 214–243. doi:10.1639/0007-2745(2007)110[214:PACTDA]2.0.CO;2. S2CID   85582943.
  31. ↑ Cole, Theodor C. H.; Hilger, Hartmut H.; Goffinet, Bernard. "Bryophyte phylogeny poster: systematics and Characteristics of Nonvascular Land Plants (Mosses, Liverworts, Hornworts)". 2021. Retrieved 6 December 2022.
  32. ↑ Villareal, J. C.; Cargill, D. C.; Hagborg, A.; Söderström, L.; Renzaglia, K. S. (2010). "A synthesis of hornwort diversity: Patterns, causes and future work" (PDF). Phytotaxa. 9: 150–166. doi: 10.11646/phytotaxa.9.1.8 .
  33. ↑ Peñaloza-Bojacá, Gabriel Felipe; Villarreal-Aguilar, Juan Carlos; Maciel-Silva, Adaíses Simone (2019). "Phylogenetic and morphological infrageneric classification of the genus Dendroceros (Dendrocerotaceae; Anthocerotophyta), with the addition of two new subgenera". Systematics and Biodiversity. 17 (7): 712–727. Bibcode:2019SyBio..17..712P. doi:10.1080/14772000.2019.1682080. S2CID   209591279.
  34. ↑ Brinda, John C.; Atwood, John J. "The Bryophyte Nomenclator". 7 December 2022. Retrieved 7 December 2022.
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