Leiosporoceros

{{Short description|Genus of hornworts}}

{{Speciesbox

| image =

| image_caption =

| greatgreatgrandparent_authority = Stotler & Crand.-Stotl. emend Duff

| greatgrandparent_authority = Hässel{{cite journal | last = Hässel de Menéndez | first = Gabriela G. | year = 1988 | title = A proposal for a new classification of the genera within the Anthocerotophyta | journal = Journal of the Hattori Botanical Laboratory | volume=64 | pages=71–86 }}

| grandparent_authority = Hässel{{cite journal | last = Hässel de Menéndez | first = Gabriela G. | year = 1986 | title = Leiosporoceros Hässel n. gen. and Leiosporocerotaceae n. fam. of Anthocerotopsida | journal = Journal of Bryology | volume=14 | pages=255–259 | doi=10.1179/jbr.1986.14.2.255}}

| parent_authority = Hässel

| taxon = Leiosporoceros dussii

| authority = (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."{{cite journal | last = Duff | first = R. Joel |author2=Juan Carlos Villarreal |author3=D. Christine Cargill |author4=Karen S. Renzaglia | year = 2007 | title = Progress and challenges toward a phylogeny and classification of the hornworts | journal = The Bryologist | volume=110 | issue=2 | pages=214–243 | doi = 10.1639/0007-2745(2007)110[214:PACTDA]2.0.CO;2 }} Cladistic analysis of genetic data supports a position at the very base of the hornwort clade.{{Cite journal |last1=Leebens-Mack |first1=James H. |last2=Barker |first2=Michael S. |last3=Carpenter |first3=Eric J. |last4=Deyholos |first4=Michael K. |last5=Gitzendanner |first5=Matthew A. |last6=Graham |first6=Sean W. |last7=Grosse |first7=Ivo |last8=Li |first8=Zheng |last9=Melkonian |first9=Michael |last10=Mirarab |first10=Siavash |last11=Porsch |first11=Martin |last12=Quint |first12=Marcel |last13=Rensing |first13=Stefan A. |last14=Soltis |first14=Douglas E. |last15=Soltis |first15=Pamela S. |date=October 2019 |title=One thousand plant transcriptomes and the phylogenomics of green plants |journal=Nature |language=en |volume=574 |issue=7780 |pages=679–685 |doi=10.1038/s41586-019-1693-2 |issn=1476-4687 |pmc=6872490 |pmid=31645766}} 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.{{Cite journal |last1=Villarreal |first1=Juan Carlos |last2=Renner |first2=Susanne S. |date=2012 |title=Hornwort pyrenoids, carbon-concentrating structures, evolved and were lost at least five times during the last 100 million years |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=109 |issue=46 |pages=18873–18878 |doi=10.1073/pnas.1213498109 |doi-access=free |pmc=3503201 |pmid=23115334|bibcode=2012PNAS..10918873V }}[https://eprints.whiterose.ac.uk/189356/1/Pressel%20et%20al%202021.pdf Advances in understanding of mycorrhizal-like associations in bryophytes] Male plants have been found in Panama.