Proselytizer

I have alluded to my graduate research in past posts, but have not fully disclosed my thesis. I have reached the point where I am finalizing my research proposal and felt it was time to enlighten you all - I know you have been at the edge of your seat!

I am developing curation methods for living collections of bryophytes in public gardens. So for those of you who do not work as museum curators, I plan on creating new ways to manage mosses in gardens. It goes beyond how to just keep it alive (which is a challenge in itself) and focuses on: acquiring, identifying, accessioning, installing, mapping, labeling and maintaining...all rolled up into one neat little manual with a small lesson in the biology, ecology and physiology of moss - yikes!

Obviously this work is quite specific to a certain group: public garden curators and plant recorders. But I am a big-picture kind of girl; I don't intend to "preach the good word" about moss to just curators. I hope this translates through the garden staff out to the garden visitors who see the moss on display.

Dicranum scoparium tufts in a Leucobryum glaucum landscape
I want to convert the general public to seeing moss in a beautiful, new light. They might not be able to go to their local garden center and pick up a sheet of Polytrichum commune, but they could try to cultivate whatever moss is already growing in their perennial beds.

Its a simple dream to of mine to have people include mosses in their plant palettes. Or at least think twice before eradicating it from their rooftops or spraying it with herbicides in their lawns (which will only make it grow faster! - but that's another post)

So for those garden enthusiasts out there, ask your local garden when they will be creating an exhibit on mosses! And all you public garden curators out there, if you don't hear from me soon, consider incorporating bryophytes into your collection today!

Maine

I am happy to announce I will be spending this summer at Coastal Maine Botanical Garden! I am very excited to get the opportunity to commune with mosses in the bryophyte friendly environment of Maine. It is another milestone in that it is the last coastal state I will visit on the east coast (or the US, except now for Alaska) and the 6th state I have lived in.

I’ll have the chance to work alongside fellow moss enthusiast Bill Cullina (if you haven’t already, go get one of his books. Of course I particularly like Native Ferns, Moss, and Grasses) and the plant recorder there, Sharmon Provan. Aside from a few potential mossy projects I will be doing the typical plant records duties that I have done for the past 2 summers, which I absolutely love.

Now I just need to find a place to live in Boothbay Harbor…

Interview

I interviewed Dr. Kimmerer back in late September 2010. Here is the final copy of the interview that will be published in Public Garden magazine in the near future!

A Love Affair with Mosses
Stephanie Stuber interviews Dr. Robin W. Kimmerer

Robin Wall Kimmerer, associate professor of environmental and forest biology at the State University of New York College of Environmental Science and Forestry (SUNY-ESF), has published numerous articles on the biology and ecology of mosses, as well as articles on traditional Native American knowledge of the natural world. Gathering Moss: A Natural and Cultural History of Mosses, her first book, won the 2005 John Burroughs Medal for Natural History Writing. Dr. Kimmerer was my academic advisor at SUNY-ESF as well as my professor of botany and the ecology of mosses. Her course “Ecology of Mosses” is what first introduced me to bryophytes; her teaching style and the course material itself hooked me instantly.

SS: You’re someone who sparked my passion for plants and started me on the path towards presenting the plant world to the public through plant collections, so it is great to get your perspective on collections and their public benefit. What is your view on public gardens, and what do you think they can offer people?
RK: The botanical literacy of the general public is sadly so limited. Public gardens are a good venue to educate folks on the many gifts like ecosystem services and cultural services that plants provide. The deeper appreciation for the ecological and cultural roles for plants contributes to people’s sense of community with the natural world. I hope that also translates into attitudes and actions that benefit plant conservation. Plants sustain us—the public’s appreciation of that fact may lead them to sustain plants. Plus, plants are just plain beautiful and fascinating, right?

SS: I completely agree! It is the bryophytes (specifically mosses) that most fascinate me. What is it about these tiny plants that made you become their advocate?
RK: Everything! One—that they are a constant source of discovery. We know so little about them and their complex lives. And all you need to begin appreciating mosses is the art of paying attention. Attention and patience are part of the "radical slowness" movement...to step back from the frantic pace of contemporary life and appreciate what is around us. Two—their diversity is an endless source of fascination. That diversity is linked, of course, to their ecological specialization. Three—their simplicity; they are excellent teachers of the lessons of "small is beautiful" and the way that they work with natural processes in order to flourish (like boundary layer ideas). Four—their cooperative behaviors, like sharing water among the colony. Five—that they can be so small and yet have such a large ecological impact. Six—their indicator value; the way their presence conveys so much about the environment. Seven—that I've been privileged to learn so much from mosses; advocating on their behalf is an act of gratitude and reciprocity, I suppose.

SS: It’s amazing how something so tiny can make such an enormous impact! I am always pleased at how open people seem to be to the world of bryophytes and how easily they experience that “wow” factor. One of the first things I suggest to people is to read your book, Gathering Moss: A Natural and Cultural History of Mosses. For those who have not yet had the pleasure of reading it, what would most surprise them about the life of a moss?
RK: I think that people are most amazed by the poikilohydric nature of mosses (their inability to retain water), and that, therefore, they have adapted to survive extended periods in a desiccated state. This is reflective of the significant ecological roles and ethnobotanical uses of mosses.

SS: All of those awesome traits are explained well in your book. What are some misconceptions you would like to clear up that might ease some concerns related to their impact and survival within their environment?
RK: People know so little about mosses, it’s hard to think they have conceptions—let alone misconceptions! Related to that, I suppose the most important misconception is that moss is one taxon. People speak of growing "moss" as if it were one thing, instead of thousands of different species, each with their own particular habitat needs. They need to understand this in order to prevent over-exploitation, conserve habitat, et cetera. This is especially an issue in the growing attention moss gets in horticulture; you can't think of "moss" generically, you have to consider the species as individuals. I guess I'd also mention the misconception that the moss [sold] in craft stores and elsewhere is "farmed" in some way. It’s not—it’s wild harvested and largely not in sustainable ways. People should know the damage done by the moss trade. That applies to peat too. Public gardens could play an important role in educating people about the consequences of moss harvesting.

SS: I remember years ago looking at a faux flower display that had sheets of moss under it. From a little sample, I was able to identify at least five species. It was sad thinking about how it had been ripped off rainforest trees to get there.

I’ve been fortunate to work at public gardens that love mosses and encourage their colonization—a great first step! Most people know that moss is slow growing, so with patience being a key factor, what conditions result in a happy moss colony? How long might it take for it to fill in?
RK: Impossible to say because all mosses are different. You might get a speedy colonization by Bryum argenteum or Funaria hygrometrica in a few months, while others take years. That's very much to my point about considering mosses as individual species. Some flourish in moist shade and deep organic matter and some, of course, in xeric places on mineral soil. Generally shade and moisture and lack of vascular competition are primary needs.

SS: Given a few essential conditions, mosses can flourish and create a nice carpet in several years. My thesis focuses on issues surrounding the curation of mosses in public gardens. This includes the myths and “tried-and-true” methods in moss gardening. What difficulties might gardeners face when incorporating mosses into the landscape?
RK: [Essentially] failure to match specific species to specific habitats and microtopographic (the shape of a surface on a micro-scale) and substrate specificity requirements for many species.

SS: It can be difficult to pay attention to something so small in scale. Why should people embrace mosses in the garden and appreciate them in forest environments?
RK: Oh, gosh –so many reasons. I haven't yet mentioned the idea that mosses contain complex ecological communities within them; that's an important element for sure. [They offer] beauty, texture, color... The notion that they are "low maintenance" is not quite accurate.

SS: Most public gardens could probably find a spot where a colony is already thriving. When creating a moss garden, my philosophy is that if you already have some, just encourage it rather than bring more in from elsewhere. Would you agree?
RK: Yes, Yes, Yes! My philosophy on moss gardening is that the gardener should create the kinds of conditions mosses will flourish in. And then the mosses will colonize on their own; if you invite them (with a proper habitat), they will come. This avoids the whole problem of trying to match transplants to specific sites; the mosses will sort it out on their own. I do not condone unsustainable wild harvesting of moss for transplant. It rarely works and wastes all those mosses and the communities they shelter.

SS: The sustainable collection of wild moss populations is a major issue. What do collectors need to be aware of when on expeditions? How much moss is needed to start a displayable collection? How much needs to remain to leave that wild population intact?
RK: We don't know the answers to these questions from research. They are important ones and we should err on the side of only collecting very common, abundant moss species with a proven track record of success in the target habitats—if they are to be collected at all.

SS: What are some better ways to educate the public on the natural history and ecology of mosses in a garden setting?
RK: I'd like to see big magnifying devices (I've heard of big lenses mounted on the ground, with kneeling pads around them for people to observe them). Messages about diversity of moss types and the associated conservation issues are important too. Ethnobotany of mosses would be a fascinating display as well.

Stephanie Stuber, a graduate of the State University of New York College of Environmental Science and Forestry, has spent the past few years working in the field of horticulture in nurseries and public gardens. She is currently in the Public Garden Leadership Program at Cornell University, studying the issues associated with the curation of mosses, which to her knowledge have never been presented as a collection by any public garden in the world. She hopes to change that. She can be contacted at sms555 at cornell dot edu

Forms

It's time again for the next installment of my series: Better Know Your Mosses!

Part 5 will be a continuation of my previous episode: How do mosses survive? Here you will learn just how different mosses really do look from each other

Growth Form

You can divide all mosses into two growth forms. They can be either acrocarpous or pleurocarpous. The singular characteristic that sets them apart is the location of the sporophyte. If it is growing terminally on the gametophyte (i.e. coming out of the top) it is an acrocarp. If it is growing out of the side of the stem it is a pleurocarp. Generally you can tell which one a moss fits into without needing to find the sporophyte by observing its habit - and I don't mean watching it bite its nails or whistling... A plant's habit refers to its morphological appearance. It could mean tree habit or an herbaceous habit. Acrocarps in mosses are generally upright and pleurocarps are generally prostrate.


Dicranella heteromalla: acrocarp

Thuidium delicatulum: pleurocarp

Life Form

Even within the 2 catagories of acrocarp and pleurocarp, mosses can look vastly different. So they have been sub-categorized into different life forms:

Dendroid: Rhodobryum roseum

Weft: Hylocomium splendens

Mat: Hypnum imponens

Turf: Polytrichum commune

Cushion: Leucobryum glaucum
There are more forms mosses can take, but these are at least most prevalent you will come across on your daily (I hope) outdoor excursions. One thing I am especially fascinated by these life forms is where they can be found. It all has to do with water. If you were to plot the frequency of these forms (from dendroid to cushion as listed above) against regions ranging from mesic (wet) to xeric (dry) conditions, you would conclude that these life forms are indeed a function of water availability.

You can see difference in morphology in areas ranging from mesic to xeric based on the nature and capacity of capillary channels within each life form to conduct water.

It makes sense if you think simply. You will find cushion forms in drier, upland areas because that form makes a dense colony, the denser the colony, the more water it can hold onto within its capillary spaces. Mosses found in saturated areas will be more "fern-like" and not as compact because of the abundance of water, they don't have to worry about loosing it. Get it?

the plasticity of moss morphology is simply amazing. You can easily judge the typical conditions of a site based on the form moss takes. Here's a real-world application: Say you are house hunting. Your Realtor takes you to see this beautiful old home. You scan around the foundation outside and notice a plethora of pleurocarpus moss colonizing the base of the home along with many little cracks in the foundation. What does that mean? It means you would potentially be the owner of a beautiful mossy home with terrible water and mold problems in your foundation!

Next time you see a little moss, read about its life in its forms; let it tell you its story and the story of its surroundings.

Scale

I am a scientist. Yet I understand that my personal life experiences and the clairvoyance (ability to read hidden messages in something) I detect in any event, as trivial as they might seem, are incomprehensible to anyone else but me; it is the way I understand the universe communicates with me.

An astrologer once advised me to follow my bliss, and only then I would lead a truly happy life. I would simply have to listen to and follow my intuition in the form of, “good feels good, bad feels bad” and opportunities will open up. The astrologer put into words what I have always felt but never consciously realized: I was put on this earth to break boundaries and stand up against the status quo. He told me I will be the one to develop new standards in my field and be an imparter of visions of the future. Of course I am not the type to accomplish this on a large-political scale, but within my own realm: my spirituality, my occupation, home-life, eating habits, et cetera. I can see myself as the first one to develop a manual in bryophyte curation techniques that will be adopted by gardens, perhaps the first to develop moss propagation techniques on a larger scale, aiding in the first comprehensive moss field guide. I embrace the idea of being different and unique; I could never want to be like anyone else but me.

A little while ago my bliss took me to Denver, Colorado. There I got to mingle with fellow plant curation and nomenclature geeks at the APGA Collections Symposium at Denver Botanic Garden. On the plane ride over I mostly had my nose glued to the tiny airplane window. The earth looks pretty amazing from up there in the troposphere. Viewing the world from that level I could see the gradual elevation differences in the topography. During autumn it is a lot easier to view the species distribution along particular microclimates. It is absolutely fascinating to view the landscape at this point in geologic time and reflect on the evolution of the planet from its inception and how life has colonized their preferential niches within the undulating land carved by glaciers several thousand years ago. Looking out at the forested areas below, the only thing I can think of is moss (of course). From this altitude the dense trees blend together creating these turfs and tufts along the land, just like moss does from our perspective. I liken this high-altitude view of the forest below as analogous to our human view of moss from our natural height. The same natural, microclimatic forces apply in the colonization of tree, shrub and herbaceous plants species along a vast expanse of land as it does for moss species along its substrate.


Really cool way to display teeny alpine plants! If only there were moss displays like this somewhere...
I am grateful to be aware of the clarity I am experiencing at this point in my life. Things are just clicking, just as the astrologer said they would. Apparently as this year is my time to wrap up some loose ends, the 1st quarter of the next year will mark some new beginnings. I cannot wait to see where my bliss will take me next!

Destiny

I have recently come to the realization that once you find your true calling in life, opportunities will fall at your feet. It has been almost comical how many people and opportunities I have run into these past few months while venturing through my life on this moss-covered path. These events are reinforcing the universe’s plan for me, as if it whispering (or shouting) “Yes, Stephanie, you are on the right track, keep going” and with each subsequent experience I gain motivation and encouragement.

Robin standing above a stone inlaid with salamander carving explaining how not only does the carving provide the perfect microclimate, but also because mosses are considered the amphibians of the plant kingdom
Earlier this month I attended a moss workshop hosted by Moss Acres in Honesdale, Pennsylvania. I was especially excited to attend this workshop because Robin Kimmerer was going to be a guest speaker and, well, we had so many things to discuss! The small group consisted mostly of landscape architects, designers and gardeners – okay, all except me. In the introduction it seemed apparent that most were there to learn how to grow moss in gardens…fast. This made me nervous. Moss is not speedy by any means, and I was afraid everyone would walk away with the notion that there is no such thing as instant moss gardens and to just give up on the idea or be prepared to deplete the local forest of its moss reserves. But these fears were put at ease as the day went on.

Al Benner gave some background on the property and their business (began by his father, David Benner) then Robin began with a little background on the evolutionary history of mosses. She reminded me of something fascinating: due to its derivation from bottom-of-the-sea dwelling algae, moss has retained its adaptation to photosynthesize at very low light levels (think not much light reaches the bottom of the ocean). That’s why it flourishes in the shady forest and underneath a thick blanket of snow. In fact there is a moss thriving happily at the bottom of Crater Lake, Oregon (over 1900 feet – the deepest lake in the US). One of the things I love the most about Robin’s approach to teaching mosses is to never forget their beauty, both within its simple physiological processes as well as the aesthetics it provides on a larger scale. Robin describes moss as “time made visible”. That is one of its greatest attributes, its ability to alter our human minds to perceive “old age” when seeing it blanketing its substrate.

Al Benner standing on their green roof
The staff proudly showed us their green roof experiment on top of a spring pump house. It looked great! I’ve been trying to advocate for the use of mosses on green roofs: they are very drought tolerant, and require a lot less substrate. They had inoculated the roof aggregate with Hypnum imponens 2 years ago and it was taking off great. This past spring, however Thuidium delicatulum took over and spread like wildfire, completely out-competing the Hypnum. Thuidium is well known as a “volunteer” species, but we weren’t complaining. In the near future they want to construct a sun-loving-moss green roof. Al took us to a sunny rock he found that had a few species growing on it and asked for their identities and if these were good roof candidates. There was Hedwigia ciliata (always found on roofs) Bryum argenteum and Cetatodon purpurea – all wonderful selections for a sunny roof! Those species would create a beautiful mosaic of color and texture on a rooftop.

Beech Grove
Our group moss-planting project ended up really being an exercise in understanding the “natural destiny” of an ecosystem: alter it any way you want, it will always want to revert back to its original state (though the extent of its originality that returns will vary). We were taken to a little beech grove at the edge of a forest with a large boulder perched to view the valley below. Immediately the group began ripping out some of the invasive vegetation and sweeping off the leaf litter from the boulder. A few of us stood back and watched a little confused as to what we were trying to accomplish here. Those who jumped in couldn’t help not noticing that the instant effects they were trying to gain by removing the vegetation and debris would only increase the erosion and wind potential in that area. All that exposed, rich humus beneath that leaf litter on the boulder would be washed away instantly. Those of us who stood back encouraged Robin to speak up: The reason why it accumulated there in the first place was because of the slope and location of that rock – its natural destiny is to accumulate leaf litter – a destiny that does not include moss (it cannot survive being smothered by debris). So creating a moss garden on that rock would only be possible if there was maintenance in removing the debris and keeping it moist (there would be water loss due to the slope of the rock). I explained that a moss garden would be possible, but it would require a lot less work on your part if you work with the natural tendencies of that ecosystem rather than fight against it. I mean, the reason why it was chosen in the first place was because it was already a special and beautiful spot; why change it?

Al exhibiting the difference in moss growth using the “milkshake method” under a biodegradable film compared to no cover (the uncovered experiment is to the left of that mossy patch
The workshop introduced ideas of “tricking” the moss into growing at a faster rate. This is what put me at ease when I feared that the attendants would not learn that moss can grow relatively fast. I already put these conditions into practice at the private estate I worked at, and shared my successful experience (Side note: I discovered this private estate was the very same one Robin wrote a chapter on in her book, I took that shared experience as another reinforcing link between us Bryophiles, really what are the odds?). I might disclose these “tricks” later on (this post is long enough), but I will say that is it just a matter of lengthening that normally short period of time when mosses can actively grow.

I loved getting to chance to sit down with Robin and the other attendants over a nice hot bowl of delicious lamb stew and talk moss. I brought up some ideas I’ve been contemplating in tackling the issues associated with curating mosses in public gardens (which happens to be the focus of my thesis). I was commend on my ideas and got great new ones. Robin also expressed her desire to create a moss field guide book and in passing I offered up my services if she needed any help, and with intense sincerity and seriousness in her face and voice she said, “Stephanie, I would love for you to help.” I was surprised and elated by her invitation, and still very excited at the prospect of helping develop a field guide to mosses: another great future opportunity!

Robin teaching us the ecological implications of preserving mosses in their natural habitats and other roles mosses play in nature
I was also happy to be proven correct in my hypothesis that the idea that mosses like acidic environments is not just because they like low pH, but because in very acidic soils many of the essential nutrients are not available to vascular plants, and therefore cannot grow there. Since mosses don’t acquire their nutrition from soil, they will happily just take over the spot that the vascular plants can’t. I’m not sure how widely known this idea is already, but I was just happy to be able to independently link these two occurrences together for my own little “a-ha” moment.
Another hopeful future goal is to develop ways to propagate mosses in a nursery setting – Robin and I agree that wild collection, however “sustainably” the collectors are gathering, is not the way to go. Those essential growing conditions would not be difficult to control, and I’m not aware of anyone who has tried.
This was such an amazing opportunity to learn, teach and network. It certainly won’t be the last time they see me! There is still so much work that needs to be done to bridge the gap between mosses and the public, it will certainly keep me busy for years to come, it is my destiny after all.

Robin Kimmerer and Cathy Cope

How?

It is time again for the 4th installment of my 6 part series "Better Know Your Mosses"!

How do mosses survive?

That is kind of a large, broad question. There are several factors that contribute to the survival of any living organism. I will keep this simple and focus three points that contribute to the success of mosses:

Mosses are poikilohydric. You rarely come across this word in biology. Basically it means that mosses do not have the ability to retain water. They do not have advanced tissues to help hold in water during periods of drought to keep photosynthesis going. Think of it as being "cold-blooded" in the plant kingdom: if it is wet, mosses are wet; if it is dry, mosses are dry.

Here's a more in-depth look: The average moss leaf is only 1 to 2 cell layers thick as opposed to several different, specialized layers found in vascular plant leaves. Moss leaves do not have an epidermis, vascular system or even stomata to regulate gas exchange and water retention like higher plants. Nutrients and water are absorbed directly into their cells from their environment. This lack of conductive tissues is also the reason why mosses are so small - they don't have this interior structure to hold them upright and allow them to grow higher like vascular plants. Of course those species that have the hydroids and leptoids (those nearly-vascular tissues) tend to be bigger in form.

A dessicated Grimmia. It really looked quite black from a distance. Here you can at least see some green showing through the silvery awns which aid in light reflection.
Grimmia, rehydrated. A much more lively appearance.
Okay, so how is it possible mosses have survived hundreds of millions of years if they can't even master the simple task of holding in water? Amazingly they can lose up to 98% of their water content and still survive! Upon dessication they enter a state of suspended animation. Everything freezes, including respiration and photosynthesis (both of which require water to function), and the plant waits for the arrival of that ever-so-essential liquid. The phrase "patience is a virtue" resonates even within the micro-mossy world.

You have probably already witnessed this neat little adaptation when coming across dried up, crusty clumps of moss on rocks or other dry surfaces. That moss is not dead (unless its yellow or brownish - then maybe it is), but if it is still a shade of green or even blackish in appearance, then it is still very much alive - just not kicking. This ability to go dormant in the absence of water gives moss a special advantage over any other plant: they are incredibly drought tolerant. Need a candidate for your green roof project? Look no further!

Of course this does not mean mosses are immortal. All species have a different level of a dessication tolerance - some more than others, and this can be directly related to their morphological variability (more on that in the future). No moss can live forever in suspended animation, though some can wait weeks, months, years or decades before water comes around again, and they will happily reanimate and go about their mossy lives.

Here's something you could do to watch this reanimation. Next time you come across a shriveled up mass of moss, give it a little drink and watch the leaves thirstily soak up the water and begin to unfurl right before your eyes - some species will even dance for you :)

Mosses are adapted to live in the boundary layer. This is why mosses are happiest in rock crevices or a muddy footprint. I have explained this awesome evolutionary adaptation in my "Wind" post. Be sure to check that out if you have not already!

Finally, mosses have a haploid dominant generation; their dominant generation is the n condition (has 1 set of chromosomes); or to phrase it yet another way: only in bryophytes can you find that the gametophyte is the main generation you see (ergo, dominant) and the gametophyte is always haploid in any plant species. (Please see my What? post for a more detailed/simple explanation of this unique life-cycle).

What possible advantage does having only 1 set of chromosomes in their dominant generation give them? If you think about it, this n condition possesses “immediate fitness”. Any unfavorable environmental conditions would immediately select against unfit mosses; they would not have a chance to pass their genes to next generation. It gives them a "speedy evolution" so to speak. They don't have much of a chance to hold onto recessive genes until conditions become favorable enough to disperse their progeny like a vascular plant can.

Perhaps a story can better explain it. Note: You will need to believe that evolution is, in fact, a real phenomenon!

Once upon a time, on a dry rock face, far, far away, a brand new generation of moss was born. He was named Bryum. It just so happened that the genetic combination of Bryum's parents' gametes resulted in a genetic code that caused Bryum to express a particular trait; Bryum had especially sparse and narrow leaves compared to other nearby populations. Poor Bryum was picked on by the others because he couldn't hold as much water in his capillary spaces like everyone else, and living on this hot, dry rock face, water-holding capacity was pretty essential. Tried as he might, Bryum just could not continue living this way, and after a short while Bryum died; he never even got the chance to make little moss babies of his own...

I didn't say this story would end happily ever after... but here's the moral: you better be suited to your habitat if you want to pass on your genes and give your offspring a fighting chance. It's a good thing that Bryum died, because if he lived long enough to make moss babies he would have passed on his thin-leaf genes them and they would have equally bleak futures. So goes nature's mantra: Survival of the Fittest. Poorly formed mosses will die out a lot faster, killing off those undesired traits at a much faster rate than would happen if they were much bigger, bulkier and tougher; able to weather through the tough times - but that would slow their evolution. So that's why mosses have remained largely unchanged for 350 million years - they were evolving at warp-speed from the beginning!

Chew on this: In bryophytes the sporophyte (wiry stalk with capsule that holds spores) is dependent on the gametophyte (the leafy green part). This means that if the gametophyte dies, it couldn't produce a sporophyte and thus its genes die along with it - that's it, no second chances for that generation. But in vascular plants the gametophyte (pollen and embryo sacs) is dependent on the sporophyte (the tree, shrub, or herb). A tree can keep sending out the same genetic information over and over again, whether or not conditions are favorable. If its gametophytes die, it can just keep on making new ones, dispersing it's genetic information in perpetuity in hopes that some of its offspring will be successful.

Despite their small stature, mosses are quite tough on an evolutionary scale - not to mention innovative! How amazing is it that they can just freeze in time without water and after it returns just pick up right as they left off and go about their lives? (Though the process of rehydration is a little more complicated than that). It's a good thing mosses didn't lose this trait over time, because without these qualities mosses wouldn't have a fighting chance against higher plants. The ability to colonize and adapt to those little spaces otherwise neglected by larger life forms definitely adds another dimension to the natural world - search them out next time and ask yourself "how do they do that?".

Stay tuned for the next installment and learn just how many shapes, sizes and colors mosses come in!