Leiosporoceros
Scientific classification Edit this classification
Kingdom: Plantae
Division: Anthocerotophyta
Class: Leiosporocerotopsida
Stotler & Crand.-Stotl. emend Duff
Order: Leiosporocerotales
Hässel[2]
Family: Leiosporocerotaceae
Hässel[1]
Genus: Leiosporoceros
Hässel[1]
Species:
L. dussii
Binomial name
Leiosporoceros dussii
(Steph.) Hässel
Synonyms
  • Anthoceros dussii Steph.

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."[3] Cladistic analysis of genetic data supports a position at the very base of the hornwort clade.[4] 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.[5][6] Male plants have been found in Panama.[2]

The Ordovician fossil hornwort Casterlorum has been assigned to this family as well.

References

  1. ^ a b Hässel de Menéndez, Gabriela G. (1986). "Leiosporoceros Hässel n. gen. and Leiosporocerotaceae n. fam. of Anthocerotopsida". Journal of Bryology. 14: 255–259. doi:10.1179/jbr.1986.14.2.255.
  2. ^ a b Hässel de Menéndez, Gabriela G. (1988). "A proposal for a new classification of the genera within the Anthocerotophyta". Journal of the Hattori Botanical Laboratory. 64: 71–86.
  3. ^ 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.
  4. ^ Leebens-Mack, James H.; Barker, Michael S.; Carpenter, Eric J.; Deyholos, Michael K.; Gitzendanner, Matthew A.; Graham, Sean W.; Grosse, Ivo; Li, Zheng; Melkonian, Michael; Mirarab, Siavash; Porsch, Martin; Quint, Marcel; Rensing, Stefan A.; Soltis, Douglas E.; Soltis, Pamela S. (October 2019). "One thousand plant transcriptomes and the phylogenomics of green plants". Nature. 574 (7780): 679–685. doi:10.1038/s41586-019-1693-2. ISSN 1476-4687. PMC 6872490. PMID 31645766.
  5. ^ Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years
  6. ^ Advances in understanding of mycorrhizal-like associations in bryophytes


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