What?

It's time for part 2 of my 6 part series: Better Know Your Mosses!

What exactly is a moss?

Mosses are non-vascular plants. This means they do not conduct water internally... for the most part. Some more advanced species like ones found within the Polytrichum and Mnium genera have primitive vascular tissue called hydroids and leptoids; analogous to xylem and phloem respectively. These tissues can be found in the stems and the costa (midrib) of higher mosses and facilitate in the transportation of water and nutrients. But as a whole bryophytes are considered non-vascular.

Mosses are spore-producing. Rather than spreading their progeny via seeds like vascular plants, mosses use spores. Here's how mosses have sex:

Augmented diagram of the lifecycle of a moss

from www.ohiomosslichen.org/MossID3.html

I numbered each step, I'll do my best to explain this as clearly as humanly possible:

1. If you pluck a piece of moss out of a clump this is what it looks like (though they do come in widely different shapes and sizes) The leafy green stuff that you see growing is the gametophyte (holds gametes) and the wirey thing with a capsule on top is a sporophyte (holds spores).

2. As the sporophyte slowly emerges from the top of the gametophyte it carries with is a piece of the old archegonial wall (see step 10). This little covering is the calyptra and may or may not be very conspicuous.

3. On top of the capsule is a tiny cap called an operculum. It covers the capsule opening while the spores ripen.

4. When the spores are ripe and ready the operculum will pop off revealing a peristome. This row of tiny teeth are thought to aid in the dispersal of spores.

5. The spores are released.

6. When a spore find a happy little spot it will begin to germinate. The filamentous green protonema emerges.

7. Small buds will appear on the protonema which will develop into a leafy plant: the gametophyte. Also forming are rhizoids: small root-like structures used to hold the moss to its substrate.

8. Shown here is a dioicous plant (moss version of being dioecious): male and female gametes (sperm and egg) on separate plants.

9. On the male plant antheridia will form, these house the sperm. On the female plant archegonia will form, each one with an egg. Only when water is available can the sperm be released and swim until they find an archegonium and travel down the neck to the egg - should they only be so lucky.

10. When the sperm fertilizes the egg a baby is born: a sporophyte, and life begins anew.

Sexual reproduction in mosses requires many factors to be in place at certain times and sometimes it just isn't worth the moss's trouble. Depending on the environmental conditions many mosses may choose to reproduce asexually through the use of vegetative propagules: gemma, brood bodies, paraphyllia, leaf fragments...

So how is the life cycle of a moss different from other plants? The difference lies in the dominant generation, i.e. the generation that you see walking around outside - sporophyte or gametophyte. The sporophyte always has a 2n condition (diploid: 2 sets of chromosomes). It is 2n because it is the product of a sperm and an egg combining which are 1n each (haploid: 1 set of chromosomes). In vascular plants the dominant generation is the sporophyte, i.e. the tree, the shrub. It is on the sporophyte (tree) that the gametophytes (sperm/egg) are borne. In mosses it is the reverse: the gametophyte is dominant: the sporophyte is borne and is dependent on the gametophyte.

That was about as simple as I could get it...

That concludes part 2...stay tuned for my next installment!

When?

Since this past September, I spend 2 hours of the last Saturday of every month attending and teaching a moss study group in Baltimore. It is a rare occurrence to find a group that studies moss for the fun of it - and no less a miracle that its within driving distance!

We are not a very structured organization; just a group of 10 or 15 people from all over Maryland. We spend our time identifying field and microscopic characteristics of these mosses. We use Crum's book, Mosses of the Great Lakes Forest to key out these plants. Don't ask me why we use this book, but I had no complaints since it happened to be my textbook in college. My personal favorite is Mosses of Eastern North America, but I don't own either volume...yet.

This month we had many newbies so that always calls for a brief beginners review and that is where I will begin here. Strap on your seat belts and get ready for part 1 of my 6 part series: Better Know Your Mosses! (credit to Stephen Colbert for that title)

When did mosses appear?

They emerged around 350 million years ago during the Devonian period. To put it in perspective, vascular plants didn't come around until about 140 million years ago during the Cretaceous period, so mosses were happily photosynthesizing for over 200 million years before trees, shrubs and herbaceous plants ever existed - it blows the mind!



Muscinae from Ernst Haeckel's Kunstformen der Natur, 1904

This painting demonstrates not only the diversity of mosses when they first started colonizing land, but also the fact that over these last millions of years they really haven't changed at all: they got it right the first time around. Now at first glance, this painting seems a bit exaggerated, and it is, but really only in the scale of the plants and the fact that those species would not live anywhere near each other based on their prefered environmental conditions. Aside from that, the Polytrichum, Sphagnum, Andreaeobryum, Ptillidium, Mnium, et cetera that you see here look pretty much the same today.

There are approximately 22,000 species of mosses worldwide that comprise 3 classes: Bryopsida, Sphagnopsida and Andreaeopsida (for all you taxonomists out there, there may or may not be more classes depending on if you are a lumper or splitter!). Bryopsida includes the true mosses (my real focus). The other 2 classes have only one genus each: Sphagnum and Andreaeobryum. Moving up the phylogenetic tree, these 3 classes are found under the Division Bryophyta. The other bryophytes can be found in Divisions Hepatophyta and Anthocerotophyta (liverworts and hornworts respectively). And all these ranks fit nicely under Kingdom Plantae. Ta-dah!

Sometimes it feels good to regurgitate this stuff...

Genesis

How did I earn my self-appointed title of "Bryophile"? How why have I designated myself the ambassador to these overlooked and under appreciated plants? Well it all began as an undergrad at the State University of New York College of Environmental Science and Forestry where I earned my Bachelors of Science degree in Environmental and Forest Biology with a concentration in Plant Biology (my fingers are tired just typing that...). I spent the first few semesters in Syracuse and the Adirondacks falling in love with plants. I took a course my junior year called the Ecology of Mosses. I've always thought mosses were cute - how often do you come across a course in their ecology?

Freshman year retreat circa September 2002. Dr. Kimmerer showing us the local flora (I'm in the red sweatshirt)

It was taught by my academic advisor and previous professor, Dr. Robin Kimmerer. At the time she had just recently published her book, Gathering Moss: A Natural and Cultural History of Mosses, a collection of beautifully written essays that explore the world of mosses and how they relate to our own lives. A must read for anyone with any moderate interest in mosses.


During this class I fell deeply into the fascinating life of mosses. It is physically impossible for me to walk through the woods, or anywhere, really, without having to stop and pet the mosses and whisper their names. I had no idea mosses lead such an intricate, yet simplistic life. I felt privileged to have had these secrets revealed to me - and in time, you too will be privy to the secret life of mosses as well.

Resolution

I figured the beginning of a new year was an ideal time to start a digital life account of sorts. As the name of this blog suggests you can safely assume there will be plenty of talk about all things tiny, green and fuzzy - specifically mosses. As one of the very few people on the planet who thinks mosses are just about the coolest things since *insert something awesome*, I feel as if it is my duty to proselytize anyone who happens to come across this site into believing that bryophytes are in fact pretty awesome. Disclaimer: There may be high concentrations of biology.

Aside from mosses, as the title alludes to, you can expect a smattering of randomness including, but not limited to, rants and ravings, paganistic lifestyle doings, secrets, revelations, natural history, apocalyptic prophecies, knitting, et cetera...

Enjoy!