How many mosses are there?

One of my bryology students told me that their friend could not believe that they were taking a course on mosses. Their friend's comment was that there is only one type of moss, right? The small green kind.

This question boggles my mind. Is there only one kind of bird? No. One kind of tree? No. One kind of moss? No. You have to get pretty specific in your definition of any living plant or animal before the answer to that type of question is yes. For example, is there only one kind of ostrich? Yes. Only one sugar maple tree? Yes. You get the idea.

So my point is there are many different types/species of mosses in the world. Just take a look at some patches of moss when you are out and about. I bet that when you get close to the mosses and really peer at them you will notice that the first patch does not look exactly the same as the the second patch.

The question that I more often get but have a hard time answering is, "How many species of mosses are there worldwide?". This presents a problem, because it depends on who you ask and whether they are a splitter or a lumper. (Basically - A splitter is a scientist who tends to find differences between organisms and then groups them in a way that creates more species. A lumper is a scientist who would look at the same organisms focus on the the similarities and then group them in a way that creates fewer or one species.) Those are not technical biology terms and these are my own informal definitions, but if you were to use either of them with a biologist who thinks about species they will most likely know what you mean.

In the end this makes for a difficult question  "How many species of mosses are there worldwide?" I have looked through a number of bryology and botany books on my shelves and here is the range of answers to this question. (The quotations are arranged in chronological order.)

Bryophyta by Parihar (1961) p.150 "... about 660 genera and 14,500 species."

The Structure and Life of Bryophytes by Watson (1971) p.16 "Some 14,000 species of moss are known and the great majority are sufficiently alike in structure to create a real difficulty for the taxonomist."

 

Biology of Plants by Raven, Evert and Eichhorn (1999) p.412  "...at least 9500 species of mosses, with new forms being discovered constantly, especially in the tropics."  

A Checklist of the Mosses by Crosby, Magill, Allen, and He (1999) p.1 "This Checklist recognizes 12,754 species. Although new species of mosses continue to be described, the number being recognized appears to be declining, because of increased synonomy."

Introduction to Bryology by Schofield (2001) p.10 "... contains approximately 10,000 species in nearly 700 genera."

Bryophyte Biology edited by Goffinet and Shaw (2009) Ch. 2 p.56 "With approximately 13,000 species, the Bryophyta compose the second most diverse phylum of land plants."

Introduction to Bryophytes by Vanderpoorten and Goffinet (2009) p.70 "Approximately 12,000 species are currently recognized,..."

From this survey we end up with an answer that ranges from 9500-14500 species of mosses. Scientists are usually comfortable with a high level of uncertainty so they may find that range a sufficient answer. Remember it's not as though there is a right answer and by giving a range scientists just don't know. The number of species is constantly changing as new ones are discovered and others may go extinct. It also depends on which expert you consult (splitter or lumper). So the answer to this question is in a constant state of fluctuation. 

I find that giving a single number is more satisfying if I do not want to go in the the whole explanation that I have given here. Usually I say that there are approximately 12,500 species of mosses and I quote A Checklist of the Mosses as my source. This count is going on ten years old at this point, but I think that it is the most accurate count that we currently have. It also looks like the two books from 2009 are following this count as well with their values that are a little above and below those of the checklist.

So, "How many species of mosses are there worldwide?" you may ask.

To that I would answer that there are approximately 12,500 (Crosby et al 1999).

Preview of the Book "Nesting Season" at Northern Woodlands Magazine

A few of the nests featured in this article appear to include mosses as part of their construction materials. At least that's what it looks like from the photos and drawings.

I wonder how many different species of birds use mosses to build their nests?

Click here to link to the Northern Woodlands Magazine article about bird nests and Bernd Heinrich's upcoming book Nesting Season.

Moss Cell Walls Like Sponges

I came across this paper when cleaning off my computer desktop today. My labmate Juan Carlos sent it to me a while back. Upon stumbling across it again I decided to give it another read.

H. G. Edelmann, C. Neinhuis, M. Jarvis, B. Evans, E. Fischer and W. Barthlott. 1998. Ultrastructure and chemistry of the cell wall of the moss Rhacocarpus purpurascens (Rhacocarpaceae): a puzzling architecture among plants. Planta 206:315-321.

This paper focuses on the unique cell walls of leafy gametophyte of this moss. (For a little review of plant cell walls check out last week's post.) Rhacocarpus purpurascens grows in the high mountains of some tropical areas. It grows in large sheets that hang from rock faces and they pick up most of their water from fog. It has been known since the 1970's that the cell walls of this plant are structurally sponge-like. (Think your morning english muffin with a lot of nooks and crannies.) Typical plant cell walls are solid. This study sets out to analyze the walls using a number of methods.

They use some high-tech techniques such as electron microscopy (scanning and transmission), nuclear magnetic resonance (NMR) spectroscopy, and cell wall fractionation. Fancy techniques such as these are great. I use both types of electron microscopy in my own research. However I also enjoy techniques that have an elegant simplicity, which is how I would describe the two other experimental methods that they use (external water conduction and water-holding capacity). Basically these methods allow the authors to ask two questions: Can these sponge-like cell walls conduct water up the moss plant? and How absorptive are these cell walls? In these two experiments they compared Rhacocarpus purpurascens to two or three other moss species that have solid cell walls.

For external water conduction the placed the bottom end of the moss stem into a tube of water and measured how far up the stem the water traveled. They found that the water did not move very far up the stem in Rhacocarpus purpurascens, whereas the other species became hydrated all the way to the tip. Thus the cell walls are not functioning in water conduction.

For water holding capacity plants were dried, soaked in water for 10 minutes and then weighed. Contrary to what you might have anticipated, Rhacocarpus purpurascens held 25% less water than the other species per gram of dry weight. (So it does not appear to be acting as a sponge, which was my initial thought when reading the paper.) However a majority of the water that this plant has access to is in the form of fog. It is not submerged when growing in its native habitat. The authors anticipate that the wall characteristics allow the available moisture to be absorbed quickly and moved inside the cell.


I think that it is pretty cool when scientific questions can be asked and answered using simple techniques. It just goes to show that scientific experimentation is accessible to more than university researchers.

Latest Moss Gardening Book

I'd like to introduce you to my latest book purchase. Native Ferns, Moss, and Grasses: From Emerald Carpet to Amber Wave, Serene and Sensuous Plants for the Garden by William Cullina of the New England Wild Flower Society.

If you are interested in gardening with mosses I think that this book would be a great addition to your bookshelf. A limited preview edition is also available through GoogleBooks. The suggestions that he gives are highly detailed including sections on: Choosing a Site, Site Preparation, Transplanting Moss, Blending Moss, Establishing Moss on Rocks, and Maintenance. I found his explanations clear and his text easy to read. I think that he covers all the steps needed to successfully maintain a moss garden. I was a little disappointed that only 13 moss species are covered. The book is heavier on the fern and grasses. The mosses that are included are rated from easy to difficult in terms of their ease to grow, which will help to point you in the right direction depending on your moss gardening skill.

I am happy to report that I am not lodging my biggest complaint about moss gardening books when it comes to this text. Often they skip over discussions of conservation, wild-collection vs. greenhouse grown, and sustainable harvesting. Not this book. These environmentally conscious threads are woven throughout the text. The author works for a top notch conservation group, so I guess his including these topics is not too surprising. It is just one of the things that I look for when reading and evaluating gardening books. Happy reading!

Moss Protonema and Lead

This week in Bryology Lab group I presented a scientific journal article about lead and mosses. It was a pretty interesting read. You may know that some heavy metals (ex. lead and mercury) are toxic. Think kids eating contaminated lead paint. It is bad for them and will make them sick. Well plants are the same way. If too many heavy metals get inside their cells they can damage the plant and make it sick.

One way that plants prevent heavy metals from entering their cells are by binding up the heavy metals before they make it inside. How do they do that you might ask? Well it is a pretty ingenious system. It has to do with their cell walls. Okay a little review. All cells are basically a sac (a bi-lipid membrane sac) filled with mainly water and other neat cell innards. Vertebrate animals give their cellular bodies structure with internal bones, insects have an tough exoskeleton that gives them shape, and plants have cell walls that help to keep them upright. Each of their cells is surrounded on all sides by these rigid cell walls that are connected together across the entire plant body. Without the cell walls plants would be a floppy mess.

Back to the connection with lead. The researchers determined that the moss plants, particularly at the protonema (filamentous) stage bound the lead to their cell walls so that it would not enter the cells. When placed in a lead bath they could even change the chemical composition of their cell walls to bind up (sequester) even more of the lead. This method does not keep all of the lead out of their cells but it is a good start. This phenomenon has been observed in the roots and pollen tubes of other plants. Boy plants are awesome!

Click on the citation below for a link to the paper.

Krzesłowska M., M. Lenartowska, E. J. Mellerowicz, S. Samardakiewicz and A. Woźny. 2009. Pectinous cell wall thickenings formation—A response of moss protonemata cells to lead. Environmental and Experimental Botany. 65:119-131.

Mosses in Malaysia

Well I sure had a whirl-wind adventure traveling around southeast asia for 2.5 weeks. The itenary was as follows. I flew from New York to Kuala Lumpur, Kuala Lumpur to northern Borneo (then back), Kuala Lumpur to Java (then back), I stayed put in Kuala Lumpur for a few days, and then home to Connecticut.

My favorite part of the trip was Northern Borneo. We were in Sabah, Malaysia near the town of Sandakan. We roomed at the Sepilok Jungle Resort, and I thought that it was a nice place to stay despite the poor review it was given in the most recent Lonely Planet Malaysia. We visited the Sepilok Orangutan Rehabilitation Center and the Rainforest Discovery Centre, both within walking distance of our lodging. With the rainy season upon us, we didn't get to explore aroung the rainforest nearly as much as I would have liked. Here are some of the mossy photos from the adventures.

All available surfaces were covered in mosses including tree trunks, fallen logs and hanging vines.

 

Here we have some mosses in the Calymperaceae. They are a very common family in the Pacific Tropics. Their identifying feature are the clusters of gemmae at the tips of the leaves.

 Some tiny critters like this ant were hiding among the mossy cover.

A few of the species that I saw had some tiny sporophytes rising above the leafy gametophytes.

The Holiday Rush

Apologies for the lack of posting recently. Unfortunately the blogging silence may continue for a little longer. This break has been full of travels for me.

I went back to Ohio for a week to visit my family. Then a week back in Connecticut. Next I was off to national meeting of the Society for Integrative and Comparative Biology & American Microscopical Society in Seattle, Washington. I presented some of the preliminary results from my dissertation research in an oral presentation. Then a week back in Connecticut. Now I am off on a vacation-adventure to visit a friend in Malaysia who is working on her dissertation research there. I will be visiting both peninsular Malaysia in Kuala Lumpur and the island of Borneo, which includes parts of Malaysia and Indonesia.

I leave this upcoming Monday so my excitement and anxiety for this adventure are mounting! We will be visiting a couple of National Parks and the moss diversity should be spectacular. I won't be doing any collecting but I do hope to capture the beauty in as many photos as I can fit on my camera!

I will have some internet access but it is only a 2.5 week trip, so I am not sure how much blogging I will do on the road. I will most definitely share all the mossy wonder from the trip with you all when I return!  So stay tuned, I will be back in the country on Feb 4th with adventure tales to tell.

The Reski Laboratory on Twitter

I just discovered that the Reski Laboratory is on twitter. They study the moss Physcomitrella patens at the University of Freiburg in Germany.

I am tossing around the idea of using twitter when I don't have time for longer blog postings. I signed up for an account to check it out and you can link to it here (Not that I have twittered anything yet). I am trying to wrap my mind around how I would use it and how it might add to the blogging. We shall see. It is another experiment!

Feel free to leave a comment about this new experiment to use twitter in association with this blog for communicating science and all that is mossy to a broader audience.

What do you think?
Yes, twitter is great and it will add to the blog.
No, twitter is evil and focusing on more blog posts would be time better spent.

Berry Go Round #22

The latest edition of the plant carnival Berry Go Round has been posted at Seeds Aside. One of my posts from this past month has been included in the lineup! Link through to checkout all the interesting botanical topics from November 2009. 


P.S. Be sure to note that the banner heading at Seeds Aside features some great looking plants.

For more about blog carnivals and my posts about the earlier editions of Berry Go Round, click here.

Some Birds Like the Moss

One of the ornithologists in my department forwarded along this article about Australian woodland bird conservation that mentions mosses.

R.M. Montague-Drake, D.B. Lindenmayer and R.B. Cunningham. 2009. Factors affecting site occupancy by woodland bird species of conservation concern. Biological Conservation Volume 142, Issue 12, Pages 2896-2903.

They focused on  patches of woodland and studied which aspects of the woodland affect the presence of 13 different bird species. One of the factors they measured was the % of the ground or rocks that was covered by mosses and lichens.

They found that 5 of the bird species were more likely to be found in woodlands with high percentages of moss and lichen cover. They lichen-ed them! (Teaching Bryology and Lichenology there were so many bad lichen jokes during the laboratory period, but I still found them totally funny.) 

The authors mention that often in other studies they do not distinguish between 'bare ground' and 'moss and lichen covered'. I would have to agree that there is a big difference between the two. Moss layers hold moisture, prevent soil erosion, and serve as housing for invertebrates and other small critters.

It is great to read that some species of birds thoroughly appreciate their moss and lichen neighbors!

Not the Model of Monophyly

Physcomitrella patens is our little model organism moss. It has recently had all of its DNA sequenced. Think the human genome project, but for mosses. The speed at which scientific information is transmitted has been greatly increased by the internet. Some scientific journals even publish papers online before they even come out in print. One of these articles in the journal Evolution focuses on the genus Physcomitrella and some of its closest relatives.

Stuart F. McDaniel, Mark von Stackelberg, Sandra Richardt, Ralph S. Quatrano, Ralf Reski, and Stefan A. Rensing. 2009. The Speciation History of the Physcomitrium-Physcomitrella Species Complex. Evolution. 000:000-000. 

Mosses were collected and identified as a particular species by their morphology (their outward appearance to the eye). Using similarities in appearance as an initial hypothesis for species relationships is often where scientists start. These hypotheses were then tested using DNA data to examine relationships among the moss species.

The Bottom Line - All moss populations that are identified as members of the genus  Physcomitrella were not found to be each others closest relatives using DNA information.

Thus the genus does not descend from a single common ancestor. Species or genera that do descend from a single common ancestor are said to be monophyletic or to demonstrate monophyly. Often this is a rule that is used when determining the names of organisms. Think of a genealogy. If you traced back to your grandmother and then you diagrammed all of her children and their children and their children, everyone who is descendant from her by blood, not marriage, you would have a monophyletic group. It works the same way in plants and in the same genus all the members hopefully form a monophyletic group.    

Since the genus Physcomitrella is not monophyletic, name changes are in order with some of these species needing to me moved into a different genus. Their data also show that some of the species are forming hybrids. Crossing a horse with a donkey to get a mule would be an example of a hybrid you might know. However unlike a mule, which cannot reproduce, some of these hybrid species are able to make offspring and continue their reproductive lines.

Their paper explores a basic question that I am very interested in: Are plants that look the same morphologically actually each other's closest relatives? Or have plants that look the same evolved from different ancestors?

Darwin's not that Cool

Charles Darwin's work On the Origin of Species is celebrating its 15oth birthday/publication-day today. A lot of news outlets are talking about the influence of this book on our scientific thinking about evolution. Checkout NPR, BBC and NYTimes for more info. I really don't have much more to add to that information-wise about Darwin. I've read parts of On the Origin and as a thinker he was way ahead of his time with some really great thoughts.

But honestly, just between you, me, and the blogosphere he is not my favorite historic (aka. dead) scientist. Beating him out by a long shot is Wilhelm Hofmeister. Ok, so you have probably never heard of Hofmeister. His position as an unknown underdog is one of the reasons I like him and his scientific discoveries. I study mosses. I tend to like the underdogs and migrate toward championing them.

Hofmeister's major discovery was to observe and outline the alternation of generations in many different kinds of plants from bryophytes to flowering plants. Basically he figured out how different parts of the plant life cycle go from gametophyte to sporophyte and then back again. He was the first scientist to figure out and discribe this important plant phenomenon.

He only had a basic education equivelent to trade school through age 15 and was entirely a self-taught botanist. Also he was very near-sighted. So much so that he sometimes did not recognize people walking down the street. However this sort of turned his eyes into magnifying lenses enabling him to see tiny plant parts and mini mosses.

Check out this scientific journal article to read more about Hofmeister and his scientific contributions.
The Genius of Wilhelm Hofmeister: The Origin of Causal-Analytical Research in Plant Development. Donald R. Kaplan and Todd J. Cooke. American Journal of Botany, Vol. 83, No. 12 (Dec., 1996), pp. 1647-1660.

Hofmeister also has a well-referenced wiki entry that appears to be accurate considering its wiki-ness.