A Video on the Moss Life Cycle

Take a break from your regularly scheduled program to check out this video on the moss life cycle. I would definitely recommend this video to students learning about mosses or bryophytes in class or for anyone who wants to brush up on their plant life cycles.

Overall I think that it is a nice video with accurate information. There was only one typo that I saw. The maternal gametophyte cap covering the sporophyte apex during its development is called the calyptra. No e after the t. 

Hat tip to Dr. Juan Carlos Villarreal for sending me this video from YouTube. 

March 2013 Desktop Calendar

Apologies for the delay in the March calendar. I have been busy working in the lab getting my moss cultures started! They are currently at the filamentous protonema stage and are growing nicely as you can see from the photo below.

I am not sure which species made it to the top of the pile for best photo. It is definitely a Funariaceae, but could be Entosthodon, Funaria, Physcomitrella, or Physcomitrium. It is impossible for me to tell which one at this stage of development (and I forgot to check the plate), but once they undergo reproduction their sporophyte capsules are strikingly different. They are still months away from that growth stage, so let the growing continue!

1 - Single click on the image to open it up in a new window. (If you use the image directly from the blog post you will lose a lot of resolution.)

2 - Right-click (or ctrl-click) on the image, and chose the option that says, "Set as Desktop Background" or "Use as Desktop Picture". The wording may vary.

3 - If the image does not fit your desktop neatly, you may have to adjust the image (Mac: System Preferences - Desktop and Screen Saver - Desktop; Windows: Control Panel - Display - Desktop) and choose "Fill screen" as the display mode of your background image.

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.

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.

Examining Moss Filaments: Protonema & Rhizoids

Every week members of the Goffinet Laboratory group meet to discuss a research journal article about bryophytes. The papers that we read range from morphological to molecular and may relate to either mosses, hornworts, or liverworts, all of which we study in the laboratory. Last week's paper focused on moss protonema and rhizoids.

Protonema are unicellular filaments of haploid/gametophyte tissue. In the moss life cycle a spore germinates to produce filamentous protonema that then develop into leafy gametophytes. At right is a photograph of the protonema of Funaria hygrometrica.

Pressel, S., Ligrone, R. and J. G. Duckett. 2008. Cellular Differentiation in Moss Protonemata: A Morphological and Experimental Study. Annals of Botany 102:227-245.

This research paper focuses on three types of bryophyte filaments: chloronema and caulonema (both types of protonema) and rhizoids. They define rhizoids as filaments that are produced only by the mature leafy gametophyte plants. They are often pigmented brown and function to attach the gametophyte to the substrate (soil, tree bark, or rock that they are growing on).

They had a number of goals for their research, but I am not going to go into all of them. The one that I found the most interesting was that they examined 200 moss species and determined the cellular changes that occur during differentiation of the caulonema and rhizoid filaments. (Differentiation is the process by which cells acquire all of the characteristics that they will have at maturity.) You may ask why just describe a maturation process inside of the cells. Well as the authors mention (and I wholeheartedly agree), it is important to describe the sequence of events that occur in these filaments because it lays the foundation for future experiments. Researchers have to know how structures develop normally, so that they have a control/baseline to compare to experiments.

Additionally, the paper is full of great images. There are light microscopy photos zoomed in to the point that you can see the nucleus inside of the cell. Some of the other images illustrate a feature that I had not heard of before. The rhizoids produce a mucilage sheath (i.e. slime) that covers the entire outside of the cell wall. The remainder of the images are transmission electron micrographs that show all sorts of cellular structures. You can see mitochondria, chloroplasts, golgi bodies and nuclei, just to name a few. In order to see these structures some serious magnification is needed. These organelles are probably magnified 10,000-50,000X. I think that it is just really fabulous that we can see all of these tiny biological features inside of the cells!

Journal Article on Growing Moss Plants

While thinking about growing mosses from scratch I remembered a helpful article that I read a while back by Dr. Jonathan Shaw. The article discusses techniques for growing mosses on soil. One of the most interesting methods that he used was a blender to grind the plants up. The plants were kept moist by an automatic misting machine, not by individual domes as I use to grow moss. He found that the mosses began to form protonema in two weeks and within three months the pots were full of leafy gametophytes.

Protonema are a plant growth stage that is unique to mosses. When the spores find a suitable location to grow they do not immediately produce leafy gametophytes. First they make a filamentous growth stage that is reminiscent of green algae. From the protonema numerous gametophytes are produced. Thus one spore can produce many leafy individuals that are genetically identical. In most species the protonema die off and the leafy plants are no longer connected. The protonema pictured here are from the moss Aphanorrhegma serratum, which I grew in the lab.

Overall I think that this is a really good article and I would recommend it for anyone who is growing mosses for research or gardening purposes.

Shaw, J. 1986. A New Approach to the Experimental Propagation of Bryophytes. Taxon 35(4):671-675.

Here is a list of the moss species that Dr. Shaw was able to grow using the methods outlined in his journal article.


Atrichum angustatum
Brachythecium salebrosum
Bryum argenteum
B. bicolor
Climacium americanum
Ditrichum lineare
Isopterygium pulchellum
Leucobryum albidum
Scopelophila cataractae
Thuidium delicatulum
Weissia controversa
W.sharpii