Field of Science

Airborne Sperm Dispersal

Both bryophytes and ferns have reproductive systems with flagellated, motile sperm. In order for sexual reproduction (fertilization) to occur water is needed for the sperm to swim to the egg. This presents a challenge for these plants; sperm can only swim so far and what happens when there is not enough water.

Some species of liverworts have devised an interesting strategy. They explosively disperse their sperms into the air! Researchers in Japan recently published a research paper that includes documentation of the distance the airborne sperms disperse and a video of the dispersal. This phenomenon has been known to occur since the early 1900's, however little attention had been given to it. The stimulus that caused the dispersal was the addition of water to the plant. Thus the explosive dispersal would most likely occur during or after rainfall.

It quite the evolutionary solution! Rather than being limited by water and distance these plants have evolved a strategy to undergo sexual reproduction with greater success. If there is not a film of water uniting one plant with a mate, then they toss their sperm into the air after a little bit of rain and they might get lucky. Checkout the video below.

Shimamura, M., Yamaguchi, T. & Deguchi, H. 2008. Airborne sperm of Conocephalum conicum (Conocephalaceae). J. Plant Res. 121: 69-71.

A New Blog Carnival

Have you ever heard of a blog carnival? Despite the fact that I spent an entire semester in a seminar discussing blogging it never came up and I had no idea what one was until a few weeks ago. A blog carnival is an online magazine that is published usually on a monthly basis. Each month a different blogger hosts the carnival and takes submissions from fellow bloggers that focus on a particular topic or fall under the overall theme of the carnival. The blogger who is hosting acts as the editor, chooses submissions, and then writes a post that links to them.

So why the lesson on blog carnivals? Well, I was invited to participate in a new blog carnival called Berry Go Round. The first edition is hosted at Seeds Aside. It is a carnival devoted to blog posts about plant life. Links to a couple of my posts on mosses were included in this carnival and I thought that I would point you in the direction. This carnival highlights some fun happenings in the plant world such as the discovery of a new species of palm in Madagascar and an idea for producing fuel from algae. There are also articles from the blogs Ontogeny and Invasive Species, which we discussed in our science communication seminar this past semester.

Some other carnivals that I checked out in my search to educate myself about blog carnivals are linked to below. Since Berry Go Round only has one issue out I thought that this might give you a better feel for what they are all about.

Only a couple more days in Costa Rica

We are preparing to leave La Selva and head back to San Jose, before returning to the states. This morning the class talked about online resources associated with tropical plants. One of the resources that we discussed is The Digital Flora of La Selva (La Flora Digital de La Selva). This is an online database that contains digital photographs of the plants growing at the biological station. The photos vary from overall habit shots to zoomed in photos of flowers or sori. Unfortunately there are not any mosses in the database. The home page mentions that they are only focusing on vascular plants. Since mosses do not have vascular tissue (xylem and phloem), which are specialized tissues in plants to move water and sugars around, they were not included. I think that this is a bit prejudice, but oh well.

I am not sure if anyone has studied the bryophytes at La Selva. I hope that they have, but I did a quick search online and did not come up with anything. I am going to ask around this evening to see if anyone knows of any bryophyte research happening in the area.

Ant on the Edge

I saw this ant hanging off the end of a liverwort yesterday and just had to take a photo. She seemed pretty confused and was not sure how to get down. I wonder why she climbed up this tree and out onto this liverwort in the first place? Searching for food or seeking on the edge bryophyte thrills?

Mosses Growing on Leaves

I have seen a ton of epiphyllous bryophytes while in Costa Rica. These are mosses or liverworts (I don't think that there are any epiphyllous hornworts) that grow on (epi-) the leaves (-phyllous) of other plants. Here are a few of the examples that I have seen.

This is a moss growing on the leaf of a bromeliad. It is in the Bromeliaceae, the same plant family as pineapples. The moss was growing very tightly appressed to the leaf surface. I was able to get some of it off after taking this picture, but it took some scraping and a bit of pulling. (photo taken at Las Cruces)

This leaf is covered by epiphyllous liverworts. Many of the older leaves on the forest plants in Costa Rica are covered by mosses, liverworts, and fungi (those are the white patches on the leaf below). Once these older leaves are overtaken by bryophytes they are pretty useless to the plant. The bryophytes intercept all of the light that the leaf would normally receive and thus the leaf carries out little to no photosynthesis. (photo taken at Las Cruces)

Peek below the fold for my favorite epiphyllous bryophyte photo.

This image shows the shadows of bryophytes growing on a palm leaf. (photo taken at La Selva)

A Tiny Costa Rican Moss

This is a small moss that I found growing on some soil. It has a distichous leaf arrangement, meaning that the leaves are coming out of the stem in two rows that are 180 degrees opposite each other. This growth forms resembles the genus Fissidens, which we have in Connecticut, but I am not sure what genus this moss is in.

I thought about bring a book so that I could key out and learn the mosses while in Costa Rica. The book to use for this area of the world is the Guide to the Bryophytes of Tropical America. It is a really great book, thus I considered packing it, but in the end decided not to. Because one it is a cumbersome hardback, two I wanted to focus on learning the ferns and three I thought that we would not have much spare time for me to spend with the mosses. Unfortunately we have had plenty of spare time that I could have spent with the mosses and the guide to learn them. I have been kicking myself for not bring that book along for the past week. Hopefully I will make it down to this area of the world again so that I can focus on the mosses and learn to identify tropical species, such as the cute one balancing on my finger.

Questing for Fern Gametophytes (Part 2)

While looking for fern gametophytes I could not help but notice this really cool moss peristome. For a review of peristome teeth check out these posts. I put the sporophyte under a dissecting microscope and then placed my camera up to the lens to take the picture, hence the grainy quality. This capsule was quite small about 2mm wide and 3mm long. An awesome part of this photo is that you can see all the green spores coming out of the capsule and sticking to the inner ring of teeth (the endostome).

Tomorrow we are leaving Las Cruces and are heading to La Selva biological station. It is located in northern Costa Rica in an area of tropical wet forests. We will spend the entire day tomorrow on the bus traveling to reach the station. I am looking forward to the change of scenery and all the new mosses and ferns that we will see. The part that I am not looking forward to is the abundance of snakes that live at La Selva. Check out all the serpentes that they have on their reptile list! I am not a fan of snakes. They make me panic and they like to hang out in the nooks and crannies with the mosses. Keep your fingers crossed that I do not run into any.

Questing for Fern Gametophytes (Part 1)

We spent an afternoon digging through moss mats looking for fern gametophytes. The main body that you would typically call a fern (the large, dissected, frond portion) is a sporophyte. Equivalent to this portion of the moss. Ferns also have gametophytes, however they are not nearly as large as the leafy green moss gametophytes. Fern gametophytes are typically less than a centimeter in size and one cell layer thick. We were particularly interested in finding gametophytes of epiphytic ferns. An epiphyte is a plant that lives on another plant. The plant that it lives on is called a phorophyte (phoro- meaning carrying or bearing). The epiphyte may are may not be parasitic on the phorophyte, but usually when people are talking about epiphytes in general they are not. The gametophytes of the epiphytic ferns are typically ribbon shaped and nestled within the fern mats that grow on tropical trees.

We collected moss mats off of trees and then dug through them in the lab in search of fern gametophytes. Here are some photos of the process and what I found with some of the photos below the fold.

Above is a piece of the moss mat that I was digging through. You can see my finger for scale.

This is one of the fern gametophytes that we found in the moss mat. I personally found one, but did not get a picture of it before passing it off to share with others. This is a ribbon-shaped gametophyte that is from a fern in the Hymenophyllaceae (filmy fern family).

While searching through the moss mat I came across this tiny snail shell. It is only a millimeter long, hence the fuzzy photo. It was so tiny and very cute.

The moral of the story is that there are tons of plants and animals besides moss growing in a moss mat. They are their own mini ecosystem. This idea is not limited to moss mats of the tropics. I have explored moss mats in Connecticut and found many interesting creatures.

Salutations from Costa Rica

I have arrived safely in Costa Rica and am in the throes of a throughly fun and intensive fern field course. We are currently at the Organization for Tropical Studies' field station called Las Cruces in southern Costa Rica near the Panamanian border.

The course that I am taking is entitled Tropical Ferns and Lycophytes, so we are not focusing on mosses. However mosses abound in this area and I have been checking them out during every spare moment. (I have been teased with joking gasps of outrage when others on the course realize that I am looking at mosses instead of ferns.) Despite differences in organism preference, we have had some great discussions and that have stimulated tons of questions about mosses. I plan to share them with you on the blog, once I look around for the answers.

Below and after the fold are some photos of the moss covered tree branches, soil, vines, and sidewalks. The mosses are everywhere here!

Moss on Tree Branches

Moss on Soil and a Vine

Mosses on the Sidewalk Edge

Off to Costa Rica

I am going out of the country for the next couple of weeks to Costa Rica. I am taking a field course on Tropical Ferns and Lycophytes through the Organization for Tropical Studies, of which the University of Connecticut is a member. During the course I will learn a ton of tropical fern species and I think that we will be doing some cool physiology studies. They had us do some advance reading on photosynthesis and water relations in plants, so I am expecting that we will carry out some studies on those topics. The course is being led by Dr. Robbin Moran, who is at the New York Botanical Garden, and Dr. James Watkins, of the Arnold Arboretum at Harvard University. It looks to be an exciting course and a great adventure!

Not to worry, I am not forgetting about my wonderful pals the mosses. I am taking my camera and will hopefully take some pictures of tropical mosses on the trip. We will have internet access and I may have a spare moment to post on this blog, but the posts may be few and far between. Thanks for your patience.

So You Want to Learn some Mosses

I have had a number of people ask me what field guides are available to learn the local mosses in their area. Ideally there would be a commercially available manual such as the Peterson Field Guide to the Ferns or the Fern Finder. Both of these are great guides to help you learn about the common species of ferns. However there is no such publication for the mosses, thus learning about mosses is a much more challenging task. There are some books out there but they do not ease you into the shallow end and teach you about mosses slowly. They pretty much toss you into the deep end of the pool and you will be in for a struggle. The main book that I am talking about, and I will name names, is How to Know the Mosses and Liverworts. It is sold as an introduction for the novice and it is okay. One of the problems with this book is that the dichotomous key is really long. A dichotomous key is a chain of choices that you make in order to identify something. (example: 1a. moss growing upright or 1b. moss growing flat against the substrate) They are commonly used to identify plants and animals. Another book that you might consider is Mosses of the Great Lakes Forest, but once again it is a bit of a challenge.

As a result of my pondering on this topic, I have emailed the publishers of both the Peterson Field Guides and the Finder Books to suggest that they come out with some books for mosses. I have yet to hear back from either of them, but perhaps if more people sent them emails to demonstrate that there is an audience for moss publications we could convince them to put one together.

If you have a spare moment consider sending a brief email extolling your love of mosses and the need for a comprehensive moss manual. Addresses are below the fold.

Houghton Mifflin Company - Peterson Field Guide Series -
or a form is online for general inquiries.

Nature Study Guild Publishers - Finder Books -

The Peat Moss Saga (Part 3)

As I mentioned earlier, Sphagnum is a very useful moss. (Pictured here is Sphagnum centrale.) It was used during World War I and II to dress the wounds of soldiers. Sphagnum, and the peat bogs they grow in, are characterized by high acidity. Recall your chemistry days; high acidity means a low pH (around 3.5 to 5.0 in peat bogs, which is close to the pH of an orange at 3.6 to 4.3 for a more familiar reference). This acidity is the feature that made Sphagnum a good dressing and kept the soldier’s wounds from becoming infected. It helped to kill bacteria, decreasing infection. In a pinch you could use Sphagnum to dress a cut, when in the wild, but I would not recommend it for everyday use.

There are many types of fungi that attack plants. In Sphagnum bogs, however, there are not many fungi that assault the mosses. This is especially odd since fungi grow well in acidic conditions. What is keeping the fungi from growing? Are there bacteria growing in the Sphagnum bogs that have anti-fungal properties?

Some scientists wanted to answer this question and they analyzed the bacteria in the Sphagnum to look for species that could kill the fungi. This might seem like a far out idea, but bacteria that surround plant roots are known to have anti-fungal properties. Bacteria with anti-fungal compounds could then be used to kill fungi that attack crop plants. [Trumpets blairing!] Mosses to the rescue!

I thought that this was a pretty cool idea, to mine the mosses for bacteria to use for biological control of fungi. In this study, the scientists isolated a number of bacteria from the Sphagnum bogs that were able to kill fungi. It will be interesting to see if this results in any commercial uses. The citation for this study is below the fold.

Blogging on Peer-Reviewed Research Opelt, K., C. Berg, and G. Berg. 2007. The bryophyte genus Sphagnum is a reservoir for powerful and extraordinary antagonists and potentially facultative human pathogens. Federation of European Microbiological Societies 61:38-53.