The Bryophytes on the Cover

The front cover of Elizabeth Gilbert's new novel The Signature of All Things features some lovely bryophyte paintings. They are from the 1905 edition of the German encyclopedia Meyers Konversations-Lexikon. I have not had the pleasure of perusing this encyclopedia, but I do have fond memories of an English version of encyclopedia Britannica. My parents bought a set when I was in elementary school. Black and red cover, crisp glossy pages. Ah, memories. Can you tell I am a bit of a bibliophile? For those of you who have not enjoyed a hardbound encyclopedia set, they were the precursor to google and wikipedia. Want to know something about a fast animal, far-a-way country, historic event, or odd fruit? As my dad would always say, "Go check the encyclopedia." It provided tons of information to answer my pressing questions and constant need to know. Sometimes my sister and I would just sit down with a volume and flip through pages, reading about interesting topics for fun. Did I mention that I grew up in rural Indiana and there weren't a lot of entertainment options?  


Back to the bryophytes of the beautiful image on the cover of The Signature of All Things. In terms of bryophyte identification, there are some complex thalloid liverworts in front with tall antheridiophores and archegoniophores springing up from the ribbons below. Antheridiophores are the male reproductive structures that produce sperm; archegoniophores are the female reproductive structures that make eggs.  On either edge of the cover are mosses with sporophyte capsules elevated on tall stalks. They are most definitely members of the Splachnaceae, the dung moss family. I love saying that name (SP-laCK!-n-ace-a-ee). It has a very dung-y ring to the name! My best guess on a species level identification is Splachnum luteum.  The common names for members of this genus are really great. They include umbrella moss and petticoat moss, which describe the shape of the capsules. I think that petticoat moss is especially fitting for the cover of a book set in Victorian times, about a woman who most likely wore petticoats. 

Parent Child Relationships continued...

The calyptra is a cap of maternal gametophyte tissue that covers the apex of the offspring sporophyte during development. My research shows that in the calyptra has a waxy cuticle that develops early and prevents water loss from the underlying sporophyte tissues. I think about this as the maternal gametophyte investing in these protective layers to keep the sporophyte safe from the harsh conditions of drying out as it grows taller and taller. 

This figure illustrates the maternal gametophyte calyptra
and its location across the stages of sporophyte development. 

An additional interpretation is presented by Haig. He views the waxy layers on the calyptra as slowing down or preventing the sporophyte from pulling up more water and potentially nutrients from the maternal plant. 

 Haig, D. (2012). Filial mistletoes: the functional morphology of moss sporophytes Annals of Botany, 111 (3), 337-345 DOI: 10.1093/aob/mcs295

These differing interpretations of the same phenomenon are not mutually exclusive. One is not right and the other is wrong. As Haig mentions, both maternal protection and restraint are likely to be occurring at the same time. This relationship between mothers and their offspring is a phenomenon that is seen across the plant and animal kingdoms.

Mosses produce Scents that Attract

Photo: Erin Shortlidge, Portland State University

I am a little behind in posting about the moss research that came out in the journal Nature a couple of weeks ago. Researchers found that a moss with separate sexes produce volatile compounds (scents) that can attract microinvertebrates, which in turn increases sexual reproduction.

Todd N. Rosenstiel, Erin E. Shortlidge, Andrea N. Melnychenko, James F. Pankow, & Sarah M. Eppley. Sex-specific volatile compounds influence microarthropod-mediated fertilization of moss. Nature. doi: 10.1038/nature11330

 

For some additional science news coverage of the research check out these articles below.

Science News - I really like this article. The journalist did a nice job of contacting other science experts, some of whom I know, to comment on the research.

New York Times - Pretty brief article, but I was glad to see they covered it. 

News Release from Portland State University - All the details and contacts. Also the title is super catchy.

This research connects to and builds on an earlier study that demonstrated that microarthropods increase fertilization rates in mosses. Now there is good evidence that the mosses are attracting the microarthropods to assist in sperm movement

Cronberg, N., R. Natcheva, and K. Hedlund. 2006. Microarthropods Mediate Sperm Transfer in Mosses Science 313: 1255. 

This research is really changing our thoughts on how we think about sexual reproduction in mosses. Animals help to move the sperm around. The plants produce scents to attract them. And even if they do dry out some sperm can survive desiccation (study below).

Shortlidge, E. E., Rosenstiel, T. N. and Eppley, S. M. 2012. Tolerance to environmental desiccation in moss sperm. New Phytologist 194: 741–750.

Overall I think it is really interesting research to read and think about. 

Spore Dispersal by Snakes

I tend to avoid snakes in life in general, but this snake is having a super cool interaction with a moss. If you look closely, it appears that this smooth earthsnake is covered in moss spores!

Close-up of the snake's head.

Close-up of the bright green spores coming out of the moss capsule. 

What do you think? I think that they look like spores on the snake. How long will they stick or how far can the snake go without them falling off? Easy to guess, hard to measure.  Probably a little ways, maybe further depending on how quickly they dry and the cover of plants the snake is crawling through. I think that spore dispersal by animals is a very interesting phenomenon and is under documented in the literature. Have a favorite spore dispersing creature or photos you would like to share?

Thanks to Tobias Landberg, a postdoctoral researcher at Murray State University in Kentucky, for taking and sending me these photos.

Moss Sperm Surviving Desiccation

When I think about moss reproduction, I usually think about the fact that mosses have flagellated sperm that require water to swim to the female archegonium that holds the egg. Researchers at Portland State University have been thinking about sperm survival when desiccated. I think that this is a really interesting question. Imagine that it rains and a moss sperm begins its journey swimming toward and egg. What happens if mid-travel the water dries up and the sperm is stranded? Can the sperm cell survive and resume its journey when it is wet again? 

In this study, the effects of desiccation on sperm cells were examined in three moss species.

Shortlidge, E. E., Rosenstiel, T. N. and Eppley, S. M. 2012. Tolerance to environmental desiccation in moss sperm. New Phytologist 194: 741–750.

They found that a fraction of the sperm were able to survive desiccation (e.g., Ceratodon purpureus, on average 17% survived) and the desiccation tolerance did not vary significantly among species. These results indicate the possibility of a sperm bank existing on the landscape. I have heard about a seed bank and a spore bank, but had not thought about a sperm bank before. I think that this is a pretty cool idea and as the authors mention has significant implications for understanding moss mating systems. That is just one finding from this paper. There is a lot more about desiccation tolerance, the effect of sucrose on sperm survival, and sperm variation. I highly recommend checking out this paper if you are interested in learning more. I think that it is good science and a well-written research article. Kudos to the authors. 

Mosses without Sex for 50,000 years

Karlin, E. F., Hotchkiss, S. C., Boles, S. B., Stenøien, H. K., Hassel, K., Flatberg, K. I. and Shaw, A. J. (2011), High genetic diversity in a remote island population system: sans sex. New Phytologist

This is a super cool article! The research was reported on both at National Geographic Daily News and Science Daily. I decided not to write my own summary of the research, since these two articles do such a good job. Check out these two sites for highlights of the research, which also includes an interview with the lead author. Scientific communication in action!  

Hot off the Geothermal Presses

 I read this study in the latest issue of the International Journal of Plant Sciences. I thought that it was a really neat study and is an easily accessible piece of scientific literature for folks to read who are not professional bryologists.

The premise - In stressful environments, studies suggest that sexual reproduction is favored. Researchers examine this idea in mosses across a geothermal gradient in Lassen Volcanic National Park in California.

Methodology - They collected data on sporophyte and gametoecia production from species in the field. (Yeah, gametoecia. I had to look this word up. It is both the gametangia and the surrounding leaves together.) They also collected data on temperature. The collection locations were divided up into geothermal and nongeothermal sites based on the temperature measures.

Also they ran a common garden experiment with Pohlia nutans to look at whether a genetic adaptation was limiting sporophyte production or if alternatively the extreme stress was the cause of low sporophyte production.

Results - Their results indicate that there were lower rates of sporophyte production, due to lower rates of gametoecia formation at the geothermal sites. These rates for both sporophyte and gametoecia production were higher at the nongeothermal sites. When plants from both types of sites were grown in greenhouse conditions these relationships disappear.

Implications - This study does not support the idea that sexual reproduction is favored in stressful environments. It actually shows the complete opposite for this species of mosses. Sexual reproduction decreases with increased temperature stress. The authors state that the "regression between temperature and sporophyte production was not high." And go on to suggest that other stresses such as heavy metals may be involved. They discuss that other studies in fungi and mosses have shown similar patterns and cite several studies.

I was wondering whether they thought that differences in light or perhaps levels of desiccation could be an influence too.

Sarah M. Eppley, Todd N. Rosenstiel, Camille B. Graves and Estefanía Llaneza García. 2011. Limits to Sexual Reproduction in Geothermal Bryophytes International Journal of Plant Sciences Vol. 172, No. 7, pp. 870-878.

Overall I thought that it was a really great study and a nice read. One odd fact is that they list 3M Corporation as one of their funding sources in the acknowledgements. I use a lot of post-it-notes to label and organize my research. Wonder if I could get them to sponsor one of my studies?

Bryophytes on YouTube

I haven't been on YouTube in quite a long time to look for bryophyte videos. My labmate Juan Carlos recommended this video. A fun highlight is that you get to meet real live bryophytes that talk to the audience (see time 3:42). The costumes that the kids have are great and it is quite exciting to see young folks learning about bryophytes!

I did some more searching on YouTube and came across quite a number of video presentations used to communicate information about bryophytes. Here a couple for your educational-entertainment.

I really liked the part in this one where the water overflows from the antheridium dispersing the sperm to the egg. However I think that the part where thy have the spore production and dispersal is a little confusing. I am not sure exactly which concept they were trying to get across in that part.

Botanical Images

For the past five years, the Botanical Society of America has sponsored a image competition to fund student travel to the annual conference. It is called the TRIARCH "Botanical Images" Student Travel Award. Out of the 83 images submitted this year, three of the images featured mosses. They are the following images:

#19 showing a mixture of small organisms including mosses, lichens and green algae.

#25 showing a bright yellow slime mold climbing the sporophytes of Dicranum flagellare.

#26 showing a cluster of antheridia in Rhizomnium punctatum.

I really love #25! The title of the image is "Ever Higher" and it is just a great description for thinking of the slime mold climbing the saprophyte stalk. I also think that the color contrast is great between the green sporophyte and the yellow slime mold. 

2009 Andrews Foray

I had a great time at the foray this past weekend! There were approximately 20 amateurs and professionals who came to study the lichens and mosses of northeastern Connecticut. I ran into an old friend who I hadn’t seen in years and I met some new folks who I hope to see in the future.

Over the course of the weekend we explored three different sites: Boston Hollow in the Yale Meyer’s Forest near Westford, Cat Den Swamp in the Natchaug State Forest near Eastford, and an area of the Windham Bog. (I didn’t make it to the last site due to a previous commitment, but that is where they said they were going.) The weekend weather was perfect! A little cool with the snap of the coming fall in the air and crisp blue skies overhead.

The first site was identified by the lichenologists as a talus slope with a wet seepy area near the road. I had to ask for the definition of talus and was told that it is a fancy word for a pile of rocks at the base of a cliff or slope. They were pretty big rocks and I probably would have called them boulders, but tallus works well too. Being out in the field with bryologists who can identify more plants than I can was a little intimidating, but it also resulted in my learning to recognize a number of new species in the field.

I spent most of my time acting as a sponge absorbing information and only took a few photos. Unfortunately when I went back to pick some to put up with this post I was disappointed to find some really fuzzy photos and only a couple that are even close to in focus. Despite that I will post a few up here for a splash of green and give you some description of them below.

Above center is some Mniaceae. (the 'M' is silent in the pronunciation) The leaves are whirled into a splash cup that is filled with male sex organs (antheridia). To the above-right is a very small moss whose spore filled capsules are not elevated on a stalk. Thus they appear to be sitting directly on the soil. This is a member of the genus Diphyscium. The above-left is a common genus that I often see in Connecticut forests, but a new species for me. It is Thuidium minutulum. I love the name. It means the miniature Thuidium and that is just what it looks like. A very small slender version of the robust Thuidium that I often see covering rocks or soil in Connecticut.

A special thanks goes out to Juan Sanchez who organized the trip and lodging.

I will have another story about the foray later this week or next. Stay tuned for more mosses...

Mosses on Science Friday

While doing some lab work today I was listening to a podcast of Science Friday from NPR. They mentioned a new web-video that had been posted about moss landscaping. I have posted it below or you can click here to check out the video at the SciFri website.

It is a nice video and has some good information if you are interested in encouraging mosses to grow in your yard. I especially like the hand drawn graphics that illustrate moss rhizoids. All of the science they discussed sounded solid. I think that they did their fact-checking well, which is always nice to see.

Typically when I meet people and tell them that I study mosses people respond with, "Oh, I have moss growing in my yard. Do you know how I can get rid of it? " I could start to outline all the ways in which mosses are fabulous and why you would never want to eliminate them. However this usually does not sway people. Instead I say, " Yes I know what you will need to do. 1) You need to change the pH of the soil by adding lime, but it is hard to do that for any large area and you might then need a lot of lime. 2) You probably have a wet area with poor drainage, which you need to fix to make the soil drier. And 3) you should cut down all the trees in your yard. The mosses will not be able to handle the sunlight and the grass will grow better. " This last statement usually results in a jaw-dropping reaction from most people and a statement that they could not possibly cut down their trees. Then they are much more open to learning to love, like or tolerate the mosses. I then go on to tell them that moss landscaping is becoming more and more popular and they should join the trend.

They also make the same the three points in the video. That pH, water, and sunlight are the main things to consider when trying to convert your lawn into a moss covered area. I also second their point about the low-maintenance nature of a moss lawn. By not requiring a weekly mow a lot of fossil fuel energy can be saved. What do you think, is a moss lawn in your future?

The Bug Mosses - Buxbaumia sp.

This was one of the interesting mosses that we saw on the Bioblitz a couple of weeks ago. It is a member of the genus Buxbaumia and is most likely Buxbaumia aphylla. There are 4 species in this genus that can be found in North America and this is the only species one of the four that has been found in Connecticut. If you are hiking just a little further north in Massachusetts you might run into both B. aphylla and B. minakatae. The way to tell these two apart are by the following sporophyte features, which are mature in the springtime.

Buxbaumia aphylla
- Capsule glossy/shiny
- Capsule with a ridge separating the Upper side from the Lower

Buxbaumia minakatae
- Capsule dull
- No ridge. Upper and Lower sides gradually merge.

The shiny capsule can be better seen on the second photo. It looks pretty dull in the first, but I think that is just the lighting. Both of the photos show the lighter upper side of the capsule that is bordered by a ridge that separates it from the lower side.

The common name for mosses in the genus Buxbaumia is the bug moss. This name refers to the off-kilter (asymmetrical) sporophyte capsule that kind of resembles a bug.

Another fact of note about members of Buxbaumia is that they have a very reduced gametophyte. They never form a leafy plant. Instead they have persistent protonema, which consists of thin filaments that may remind you of algae, if only you could see them. These protonema do produce sex organs (antheridia and archegonia). Add a little water to the mix and a sporophyte is produced via sexual reproduction. Since there is no leafy gametophyte for Buxbaumia the sporophytes appear to be sticking out of the bare soil as you can see in the photo below. Most mosses have a persistent gametophyte that is large and the sporophyte stays attached to it through its life. Since it lacks this feature this makes Buxbaumia a bit of an odd-ball.


If you have ever seen insects displayed in a natural history collection or museum they are mounted on pins stuck through their body and then poked into the bottom of a lined box. That is what I think the Buxbaumia sporophytes resemble. Specifically, they remind me of stink bugs, which one of my former office-mates studied for his dissertation. Keep your eyes peeled for this cool moss the next time you are out walking. They are a nice little find.