News from IAB

The mission of the International Association of Bryologists (IAB), as a society, is to strengthen bryology by encouraging interactions among all persons interested in byophytes.

Friday, October 30, 2020

Stomata are not that important… for bryophytes

Stomata of bryophytes are only present in the sporophyte generation of mosses and hornworts; liverworts do not have stomata. These structures are morphologically similar to stomata in the rest of land plants, consisting of a pair of guard cells surrounding a pore. However, the role of stomata in bryophytes has been questioned since guard cells do not close the pore in hornworts and have limited movement in mosses. 

Octoblepharum capsule and stoma

Sporophytes may use stomata in gas exchange for photosynthesis to partially support itself, but bryophyte stomata are also involved in drying and dehiscence of the capsule. The best example is the pseudostomata of Sphagnum that do not form a pore and are the first cells to dry, changing the shape of the capsule to release the spores. This role in drying the capsule to gradually release spores can explain why stomata are mostly located at the base of the capsule, or why some mosses have very few or no stomata at all.

Stomata of tracheophytes are essential for sustaining their lifestyle and the absence of stomata is recorded only in aquatic plants. This is not the case for bryophytes and taking into account the distinct function of bryophyte stomata, the widespread records of mosses that do not have stomata is not surprising. In our recent study (Renzaglia et al. 2020), we found that stomata are absent in species of 74 genera (40 families!) that accounts for over 60 independent losses. In terms of development, stomata are relatively easy to lose; interrupting one or several key genes for stomata formation can lead to stomata-less capsules. Unfortunately, not a single nor combination of environmental or phenotypic characters can explain the absence of stomata. Capsules of aquatic or semiaquatic mosses always lack stomata, but this explains very few losses, and reduction of the sporophyte can lead to smaller guard cells and perhaps a reduction in the number of stomata but not complete loss. In the last decade, the study of bryophyte stomata has greatly advanced our understanding of stomata evolution, each study adding a piece to the puzzle, but some of the oldest questions as of why some bryophytes do not have stomata remain unsolved.



Renzaglia, K.S., Browning, W.B. and Merced, A., 2020. With Over 60 Independent Losses, Stomata Are Expendable in Mosses. Frontiers in Plant Science, 11, p.567. doi:10.3389/fpls.2020.00567

Tuesday, July 28, 2020

Highlights of IAB IMOSS SEB 2019 Joint Conference

We are happy to share selected contributions from IAB IMOSS SEB 2019, the 2019 International Association of Bryologists (IAB), International Molecular Moss Science Society (iMOSS) and la Sociedad Española de Briología (SEB) joint conference, held in Madrid, Spain, on July 9-12, 2019.

The papers are published in the journal Frontiers in Plant Sciences and listed below:

Enjoy the reading.

Sunday, May 10, 2020

Life without sex, the sad story of an emigrant

Nothoceros aenigmaticus,  female patch (US)
Sexual reproduction plays an essential role in species’ survival and maintenance and hence is, not surprisingly widespread across the Tree of Life. However, clonality and other forms of asexual reproduction do also exist, especially in plants. The hornwort Nothoceros aenigmaticus is a good example of a plant reproducing asexually and clonally as its male plants seem to produce non-functional sperm cells. This hornwort is distributed in the Southern Appalachians (SA) (United States), Mexico and in “alpine” regions of tropical South America. Unlike elsewhere in its range, male and female plants in the US are geographically separated by ca. 30 km across rivers and mountains, as they grow on rocks in different watersheds of the Tennessee and Alabama Rivers (SA). Whether male and female populations were geographically isolated to the extent that migration, and sporadic sexual reproduction was completely absent, and hence whether these populations relied always exclusively on asexual propagation was unknown. Resolving this uncertainty is critical to assess the vulnerability of these populations to environmental change.

Southern Appalachians, sampling sites
To confirm the total reproductive isolation, reconstruct its origin, and assess the mode of reproduction of N. aenigmaticus in SA, we analyzed genetic data of more than 250 individuals of the species. Nothoceros aenigmaticus likely immigrated to the US from sexual Mexican ancestors about 600–800,000 years ago. The genomic data confirmed the absolute reproductive isolation between sexes and the absolute genetic isolation among SA populations. Populations from contiguous watersheds share clones, but individuals lack mixed genetic traits, consistent with the lack of sexual reproduction, as is their overall reduced genetic diversity.The SA drainage system is thought to have been remodeled by geological processes during the Pleistocene glaciations, which could have mixed genotypes from contiguous watersheds.  This low overall extant genetic diversity and the extreme sex segregation point out the high vulnerability of N. aenigmaticus to extinction in the SA under major alteration of the habitats.
Special thanks to Paul Davidson for sharing photos of the species.
The link to the paper: 
Alonso-Garcia M, Villarreal JC, McFarland K and Goffinet B (2020). Population Genomics and Phylogeography of a Clonal Bryophyte with Spatially Separated Sexes and Extreme Sex RatiosFront. Plant Sci. 11: 495. doi: 10.3389/fpls.2020.00495.

Tuesday, February 4, 2020

Announcing Eagle Hill Institute’s seminars on bryology in 2020

Eagle Hill is on the coast of eastern Maine between Acadia National Park and Petit Manan National Wildlife Refuge. 

May 31 – Jun 6 … Introduction to Bryophytes and Lichens … Fred Olday
Jun 7 – 13 … Mosses in the Field: A New Approach to Identification … Jerry Jenkins and Susan Williams
Jun 7 – 13 ... Tardigrades: Ecology, Identification, and Biology ... Emma Perry
Jun 28 – Jul 4 ... Liverworts and Liverwort Ecology ... Blanka Aguero
Aug 23 – 29 ... Diversity and Evolution in the Moss Order Funariales ... Bernard Goffinet and William Buck
Oct 9  – 11 … Bryophytes: Mosses and Liverworts (weekend workshop) … Fred Olday

The following flyer has links to individual bryology seminar flyers:

For general information and a calendar of all seminars, see: … 207-546-2821 Ext 4

Chase Uy and Devyn Adams
Assistant Program Managers / Administrative Assistants
Eagle Hill Institute

59 Eagle Hill Road, PO Box 9, Steuben, ME 04680

207-546-2821 Ext. #206

Monday, January 14, 2019

Announcing Eagle Hill Institute’s seminars on bryology in 2019

Announcing Eagle Hill Institute’s seminars on bryology in 2019
Eagle Hill is right on the coast of Eastern Maine, between Acadia National Park and Petit Manan National Wildlife Refuge. 

May 26 – Jun 1 … Introduction to Bryophytes and Lichens … Fred Olday
Jun 9 – 15 … Mosses: Structure, Ecology, and Identification … Jerry Jenkins and Susan 
Aug 25 – 31 … The Moss Family Grimmiaceae, with a Focus on the Genus Schistidium … Terry McIntosh
Oct 11 – 13 … Bryophytes: Mosses and Liverworts (weekend workshop) … Fred Olday

The following flyer has links to individual bryology seminar flyers.

For general information and a complete calendar …
office  at … 207-546-2821 Ext 4

Chase Uy, Assistant Program Manager