Field of Science

Moss Life Cycle 3

The spores land on a suitable substrate (either soil, tree bark or rocks, depending on the species) and grow to form a filamentous mat, called protonema (7 o'clock). These protonema filaments have been compared to both algae and rhizoid filaments that attach bryophytes to their substrate.

Each protonema mat can produce many leafy buds that will develop into grown mossy plants (9 o'clock). Thus you can have many individual gametophyte stems in the same patch that are genetically identical to each other. Think clones from your favorite sci-fi movie. All that is needed is a single spore to produce an entire mossy patch.

And there we have it. We have made it all the way through the moss life cycle, hopefully without to much brain strain and confusion. If you have any questions about the life cycle feel free to drop me a line in the comment section.

The Moss Life Cycle 2

The last we heard form our moss life cycle we had arrived at fertilization. This process produces a diploid sporophyte that has two sets of chromosomes per cell. The sporophyte starts out as a small embryo (12 o'clock photo) that grows (2 o'clock photo) and grows (4 o'clock photo). The sporophyte consists of a stalk that elevates the capsule, also called a sporangium, "high" into the air. (Height is relative. The stalk is only a few centimeters tall, but it is much taller than the green leafy gametophyte.)

Inside the capsule, spores (6 o'clock) are produced. They are formed by the cell division process of meiosis. This process takes diploid sporophyte cells and produces haploid spores. Basically it takes the number of chromosomes in a parent cell and decreases them by half in the child cells. These spores leave the capsule flying on the wind and are the part of the moss life cycle that is the main dispersal unit.

They land on a suitable place to grow and... (stay tuned for the continuing adventures of the moss life cycle.)

Bryonet moves to the Blogosphere

Bryonet is an email discussion group operated by the International Association of Bryologists. This listserve facilitates communication among professional bryologists and is a forum for posing questions about bryophytes to a wider audience.

Now this listserve has stepped into the blogosphere and can be found at The most recent list of posts center on the latest bryophyte classification and a discussion of monophyly.

Stay tuned for upcoming discussions and announcements.

Mosses and the Masses

Ethnobryology is the scientific study of the relationships between people and bryophytes. Some of the uses that people have for mosses and their bryophyte pals include: pollution indicators, decoration in horticulture, fuel, and medicinal purposes. The article that we read last week in laboratory group focused on both folk naming of mosses and their uses in traditional cultures.

Blogging on Peer-Reviewed ResearchHarris, Eric S. J. 2008 Ethnobryology: traditional uses and folk classifications of bryophytes. Bryologist 111(2):169-217.

The discussion of the naming of mosses was really interesting. Dr. Harris points out that many small organisms tend to be lumped together into a group and all called 'mosses'. These include lichens, red algae, lycopods, and the flowering plant Spanish moss. A good point that he makes is that people operate on a large scale from centimeters to kilometers. Mosses are small and the features that are typically used to tell species apart are super tiny and difficult or impossible to see without a microscope. So its small, green, hard to tell apart, then people historically called it a 'moss', whether on not the organisms were actually close relatives.

Dr. Harris identified 150 species with traditional ethnobryological uses. The largest category was medicinal (41%), with uses ranging from treating heart conditions to regrowing hair. Many of these treatments are used and were determined from Traditional Chinese Medicine. In addition to medicinal mosses are used for chinking spaces in the walls of houses, decoration, cleaning, packing, and bedding. This article makes it apparent that traditional cultures are much more connected to the plants that surround them and use them in their everyday lives.

Despite all these uses, most people in the USA probably do not have much personal use of mosses in their daily lives. Besides studying them professionally, the only time I think that I use them is when peat moss comes mixed in the potting soil that I buy for my houseplants. If you have any other uses for mosses in your everyday life feel free to share them in the comments section.

The Moss Life Cycle 1

If you remember anything about plants from biology class you might recall learning about life cycles. Typically this is a challenging and dreaded concept for students to learn. Life cycles involve a lot of new terminology and there are different cycles for every group of plants.

Personally I really like life cycles and I think that they are critical to understanding plant biology. The life cycle of mosses is something that I think about on a daily basis, but I know that is a little out of the ordinary. Below, I introduce the moss life cycle using the moss species that I study, Funaria hygrometrica, so that those of you who aren't as intimately involved with plants would have a good summary of how it all works.

I am going to break this topic down into a few posts since it is a lot of information to digest at once.

Starting on the far left (9 o'clock) is an image of the leafy green gametophyte (aka. the moss plant). This portion of the life cycle is haploid, meaning that it has one set of chromosomes per cell. It is different from the large photosynthetic portion of most plants which is diploid with two sets per cell. It is photosynthetic, capturing sunlight water and carbon dioxide to make sugars.

The function of the gametophyte in the life cycle is to make gametangia. Gametangia (antheridia- male & archegonia - female) are the sexual reproductive structures. Thus the gametophyte is the sexual stage of the life cycle.

At 11 o'clock are two images of these sexual reproductive organs that are produced by the leafy gametophyte. To the far left are the antheridia and below toward the right is an archegonium.

The antheridia are the dark brown structures that each produce hundreds of sperm. The single thin structure is an archegonium which contains only one egg per. The sperm and egg cells are also called gametes.

So we have gametophytes (mossy plant) that make gametangia (antheridia & archegonia) which produce gametes (sperm & egg). All of these structures are haploid and are produced by mitosis. In this process of cell division there is no change in the number of chromosomes per cell .

If you have any tips or comments on learing about the life cycle of mosses, feel free to share in the comments section. Stay tuned for the next installment of the life cycle.

Berry Go Round #10

The tenth edition of Berry Go Round has been posted at 10,000 Birds. Berry Go Round is a monthly blog carnival all about plants. Enjoy!

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