The Knothole Moss (Part 2)

Here is an up close and personal shot of the peristome and capsule of Anacamptodon splachnoides. This is the portion of the moss that enabled me to identify it to species.

Features of Note:
1. The capsule is upright with a constriction just below the opening of the mouth.
2. The exostome (outer ring of teeth) consists of 16 teeth that are joined in pairs at the base and are yellow-brown in color. When dry they are curved back away from the mouth as seen here.
3. The endostome (inner ring of teeth) is less obvious. It is composed of 8 or 16 thin filaments that alternate with the larger teeth. They are red-brown in color and are approximately half the size of the larger exostome teeth. These filaments are a little hard to see in this photo. If you zoom in you may be able to see them projecting into the opening of the mouth. With a hand lens and in person they are a great deal easier to see.

The Knothole Moss (Part 1)

This small moss occurs in dense, dark green mats and is typically found growing on wet tree bark in sheltered crevices such as knotholes. The bark that it grows on is usually soft and rotten. I found this specimen growing on a decaying tree stump in a Connecticut forest. This species has a widespread, but sporadic distribution across eastern North America. (I hadn't known this fact when I identified it, but I guess that means I was pretty lucky to find this species.) The leafy gametophyte portion of this plant resembles a number of other plagiotropic or creeping mosses. (Plagiotropy is when the plant is orientated parallel to the surface it is growing on.) The sporophyte capsules are upright with the mouths open to the sky. The defining features that I used to identify this species involve the peristome teeth. ( I have a zoomed in shot of thees teeth that will better illustrate these diagnostic features.) The scientific name for this species is Anacamptodon splachnoides.

New Goffinet Lab Website

One of the labs that I work in at the University of Connecticut is the Goffinet laboratory. I am very pleased to report that we have a new website for the lab! It highlights all of the projects that we currently have going on. There is also a list of recent publications that members of the lab have participated in. The best part is that all present and past lab members are listed with their respective research interests! If you are interested in any of the research and nerdy pursuits of my bryophyte loving pals you can check out the new website. (Yes that is a picture of my advisor skydiving on the front page of the website.)

Timmia Peristome

This is an image that I submitted to the http://www.botany.org/plantimages/ImageData.asp?IDN=ca07-029Botanical Society of America's student image competition last summer. I was very surprised and excited to be awarded second place in the competition. All of the images submitted in the competition were added to the society's online image collection, which is available for nonprofit educational or private non-commercial uses.

Below is the description of this image that I used for the competition.
Have a Happy Thanksgiving!

The peristome is located around (peri-) the mouth (-stome) of the moss capsule, a structure which contains the spores. For the past 200 years, peristome characteristics have played an important role in defining major groups of mosses. The peristome shown here has a unique morphology and is an identifying feature for the Timmiaceae. This scanning electron micrograph of Timmia megapolitana has been colored to highlight the two layers of the peristome. The endostome (inner layer, colored in orange) consists of a membrane that is topped by 64 filaments, while the exostome (outer layer, colored in yellow) consists of 16 large teeth. These teeth have the ability to move in response to humidity, thus opening and closing the mouth of the moss capsule. This movement facilitates the release of spores (colored in green) under optimal dispersal conditions.

New Pocket Knife

It finally happened. Despite my best efforts, I lost my favorite and only pocket knife. I was out collecting plants before class and was using my knife to cut off some fern fronds. I thought that I placed it back in my pocket, but when I arrived at the car it was no where to be found. I backtracked but could not find it in the brush or along the trail. I think that one of the problems was that my old knife was all black, and thus hard to see when dropped.

A good pocket knife is an essential item for collecting moss. I use it in the field to scrape moss of tree bark or stones and to dig small pieces of moss out of a larger patch. In addition to my hand lens, it is a tool that I always take with me into the field. So, I searched online to find the same brand of pocket knife, because I really liked my lost one. The upgrade that I made was to buy the same knife in bright orange. Hopefully this will keep me from loosing it in the brush. I am looking forward to going out in the field and using it to hunt down some moss!

Two Little Gemmae

So here they are! The long awaited and elusive Tetraphis moss gemmae. These crafty creatures can be difficult to photograph when they are tucked down inside their comfortable gemmae cups. All it takes is a little coaxing from a pair of forceps (aka. tweezers) and they will reluctantly float out into a drop of water. This pair floated together for a perfectly posed picture.

These gemmae are very small, like many moss parts. I didn't measure them, but they are definitely smaller than a millimeter. (maybe a scale bar would be good for next time) Due to their miniature stature, this photo was taken using a compound microscope. From this angle it can be seen that the gemmae are one cell thick near the edges and several cells thick in the center, hence why the light does not shine through in that area. Microscopes are so very great! Those are individual cells that you can see in the photo, with little green chloroplasts inside of them. Chloroplasts are the organelles in the cell where photosynthesis occurs and are the structures that cause plants to appear green. The gemmae are attached to the inside of the gemmae cup via a single strand of cells. A piece of a cell wall from that strand can be seen sticking off to the right, of the gemmae on the right.

The Cup Up Close

This is a zoomed in photo of a couple of Tetraphis gemmae cups. The cups are composed of multiple leaves at the apex of the moss that are overlapping. It is not a solid structure like a teacup. (Just an fyi for your imagination image.) I was hoping that the gemmae would be visible, but they are not unfortunately. They are located in the dark area in the base of the cup.

Gemmae Cups

These cups are located at the apex of the leafy moss and function in reproduction. The moss makes little discs of plant tissue inside the cups called gemmae. These gemmae are moved away from the parental plant via a splash-cup dispersal mechanism. It sounds high tech, but really is just using the power of rain. When rain droplets land in the cup the gemmae are dislodged and can be carried in the water as it splatters away from the moss plant. The gemmae may not be dispersed very far, but it is far enough that this structure is advantageous for the plant to have. This is a from of asexual or clonal reproduction. The plant has made a mini copy of itself that can grow into a new moss plant.

The cups are a common and easily recognized feature of the moss genus Tetraphis. There are two species that can be found in North America, Tetraphis geniculata and Tetraphis pellucida. Tetraphis geniculata is rare and grows in limited northern areas on both coasts of North America. It comes as far south as New Hampshire, but has not been sited in Connecticut. The image I have shown is of Tetraphis pellucida (once again taken at the Goodwin State Forest). This species is widespread across temperate areas of North America and is quite common in Connecticut. It grows most commonly on rotten tree parts (logs or branches) on the forest floor. Its common name is the Four-Toothed Moss.

The Land Plant Tool Kit

We read an interesting scientific journal article in Bryology reading group today and I thought that I would share some of the moss related highlights.

Floyd, Sandra K. and John L. Bowman. The Ancestral Developmental Toolkit of Land Plants. International Journal of Plant Science 168 (1):1-35.

The main point of the paper was to compare the developmental genetics across an array of land plants, from mosses to ferns to conifers to flowering plants. The authors analyzed the functions of the genes in developmental systems (those systems that control how a plant grows and changes through its lifetime) to see how different types of plants use the same genes to perform different functions.

1. It was noted that genes present in mosses have been co-opted for different functions in other groups of plants. Basically, this means that rather than new genes evolving the plants utilize the genes that they already have in new ways.

2. The developmental toolkit of mosses has many of the same families of genes as flowering plants. A gene family is a group of genes that are similar to each other, but may have different functions. All the members of a gene family are descendant from an original gene that during the course of evolution was duplicated to produce multiple copies in an individual plant.

3. Mosses typically have fewer members of a gene family than flowering plants. The analyses of moss genetics are based on Physcomitrella patens. This species is the model organism moss. The entire genome of Physcomitrella patens has been sequenced by the Joint Genome Institute, similar to the human genome project, but for a moss. It is available for use by the scientific community and is also open to the general public on the web. It provides a great resource for scientists to better understand how mosses develop and the genetics behind it. They are also offering a workshop in Freiburg, Germany to learn how to throughly utilize the genome and the computer software associated with it.

Overall I think that it is a pretty cool topic to ponder. Similar genetic systems are controlling the growth and development of both small mosses and large woody plants (aka. trees).

Wild Moss Video

I decided to search on YouTube this afternoon to see if there were any interesting videos of mosses and I came across this one. Its title is Spinning Plant Thing and the video along with comments regarding it can be seen here. It is a pretty entertaining video and a fun example of people observing the world around them, but having no idea what they are looking at. My favorite part is when they hypothesize that it is an alien!

What they are actually observing is a moss sporophyte, which consists of a stalk and capsule at the top. The moss species is most likely Funaria hygrometrica. (You can see the leafy gametophyte of this species in my post from October 5th.)

I can also explain the spinning. Funaria hygrometrica's common name is the cord moss, because the stalk that holds the capsule is very twisted when dry, like a cord of rope. When they add water it is absorbed into the cells and they straighten out and untwist the stalk. As the moss dries back up it twists again. This phenomenon is due to the arrangement of the cells in the stalk. The sporophyte is actually attached to the leafy green gametophyte part of the moss that it sticking out of. That part is hard to see in the video but they notice it is growing out of a patch of moss. I don't blame them for thinking that they were looking at two different plants the sporophyte and gametophyte of mosses look very different. One is leafy and green, while the other is leafless and usually yellow or brown. The part that people usually think of when they think of a moss is the leafy green portion.

Why are moss plants so short?

Here is a photo demonstration of the height difference between mosses and other plants such as trees. The mosses are in the foreground mixed in amongst the grass. They measure in at about 6 centimeters or so tall. Whereas the trees in the background are over 10 meters (1,000cm) tall. {Dig back for your scientific conversions if you have not used them in a while. There are 100 centimeters in a meter, so the decimal is moved two places to the right to convert from meters to centimeters}

So what is the cause of this extreme difference in height?

The answer is Water. Water is one of the required elements for plants to carry out photosynthesis and live. Plants such as trees absorb water through their root systems and then transport the water to their leaves, the site of photosynthesis, through conducting cells. The cells that move water from the roots to the leaves are called xylem cells. These cells are dead at maturity and are very tough. They are the type of plant cell that composes wood. The substance that adds to the strength of these cells and makes them retain water to function as internal plant piping is a compound called lignin.

Mosses however do not have lignin in any of their cell walls and they do not have xylem cells either. Thus mosses do not have an efficient system for transporting water within their body long distances. Mosses absorb all of their water from the outside environment directly through their leaves and stem. (Imagine drinking through your skin.) Most plants must be small in order to keep their entire body hydrated and thus are limited in the height to which they can grow while still maintaining wet leaves. Also without the strength that xylem cells provide a very tall moss would be super flimsy. It would be like trying to build a tree out of wet spaghetti noodles. Quite the difficult task. Mosses have thus maintained a small stature for millions of years and despite the time have not gotten any taller.

Sphagnum centrale

This is a cross section through a Sphagnum leaf. The leaf is unistratose, one cell layer thick and the pattern of chlorophyllose cells interspersed between hyaline cells can be seen. In this leaf the chlorophyllose cells are oval in shape and located directly in the middle of the line of cells. Examining the leaf cells in this manner is used to distinguish species of Sphagnum. The chlorophyllose cells may be a particular shape and they may be located toward the upper or lower surface of the leaf. Unfortunately this is a characteristic that requires making a very thin section through a leaf and a compound microscope. As I mentioned earlier determining the species of Sphagnum that you locate can be challenging, but not impossible.

The Peat Moss Saga (Part 2)

The plant body of Sphagnum mosses are made up of two types of cells. They are composed of small chlorophyllose cells that function in photosynthesis, the process by which plants use water, air, and light to make sugars. Most types of mosses are mainly composed of these green chlorophyllose cells. Sphagnum however has many large hyaline cells that make up the plant. These cells are colorless, transparent and open to the outside environment with pores in their cell walls. These cells function as storage reservoirs for water and enable peat moss to function as a plant sponge. With these spongy cells, Sphagnum can hold up to 20 times its dry weight in water! This is the main reason that Sphagnum is the most economically important group of mosses. Due to its absorptive properties peat moss has been used historically by Native Americans in baby diapers and during World War I in bandages. Peat moss is widely used in the horticultural trade as a soil additive and to pack plants for transport.

The photograph shown above is of a Sphagnum leaf. It was taken using a compound microscope looking at the leaf surface. Keep in mind the leaf is only one cell layer thick. That is how we can easily see through the leaf. Thin chlorophyllose cells are packed between the large hyaline cells. The hyaline cells have wall thickenings that appear as bands across the cells. Also circular pores can be seen enabling water to enter the hyaline cells.

BRYONET

I subscribe to a bryological listserve that is sponsored by the International Association of Bryologists called Bryonet. (Bryology is the scientific study of mosses, liverworts and hornworts. These are three separate lineages of green land plants.) I received a message over the listserve today that is related to this week's post about Sphagnum and thought that I would share. It is the announcement for the 4th International Meeting on the Biology of Sphagnum. I mentioned previously that Sphagnum is highly important group of mosses. Based on the fact that there are enough people in the world interested in Sphagnum to warrant an international meeting, I would say that there are a number of other people out there who share my opinion.