Field of Science

The Mosses of her Passion - The Signature of All Things

From the LuEsther T. Mertz Library of
The New York Botanical Garden, Bronx, NY
***Spoiler Alert***
This post may contain plot details and quotes from The Signature of All Things
Proceed with caution!

The mosses have finally arrived as significant characters in Part 3! We discover that Alma has decided to devote her time and energies to studying mosses in the genus Dicranum and she becomes the world expert on this group.  I am most familiar with Dicranum scoparium, the broom moss, which is common in eastern deciduous forests. It's common name comes from the leaves that are all curving in the same direction, as though the moss had been used to sweep the floor. It is one of the first species I like to teach people when walking in the woods. It is charismatic and easy to recognize. 

The moss pictured in this plate is Dicranum squarrosum. The specific epithet of the scientific name describes the leaves of this species, which stick out at right angles to the stem. This arrangement is due to the leaves having a bend in them, which can be seen at the bottom center of the plate. 

It was a bit of a tease, or foreshadowing, that these images of Dicranum were placed at the end of Part I, long before Alma discovered her passion for mosses. Mostly it had me wondering when we would start to hear more about the mosses.  Stay tuned for more to come on the mosses of Part 3!

The Signature of All Things: Part 2 - Catching bryophyte fever

***Spoiler Alert***
This post may contain plot details and quotes from Parts 1 & 2 of The Signature of All Things. Proceed with caution!

The second part of The Signature of All Things focuses on the childhood of the main character Alma Whittaker. In my mind the true main characters, the bryophytes, have yet to truly arrive on the scene. There is a brief mention of mosses being used by birds as material for nest building. Alma also uses mosses to fill the chinks in the walls of her study to cut down on winter drafts. Hornworts come up during a scientific discussion between Alma and her colleague George Hawkes. He describes them to another friend as "...among our least sophisticated plants-". I take mild offense to that statement. I think hornworts are super interesting and highly sophisticated in their ability to establish a mutualistic interaction with cyanobacteria (blue-green algae). They have pores on the underside of the plant that open to allow the algae to enter. The algae then live and grow inside of the hornwort helping to fix nitrogen, making it available for the hornwort to use. I think that establishing a relationship like that is pretty sophisticated. Don't you?

At the tail end of Part 2 bryophytes take their rightful place at center stage. Alma has a revelation that right beneath her nose, on the land she has known her entire life, is a world unexplored. The miniature world of mosses. An entire rock may be covered by dozens of species that occupy distinct niches. A little sunnier over here, a little wetter over there, makes for diverse habitats even within a few feet. It is amazing how small changes in the microclimate can make such a big difference to the bryophytes. The description of Alma's epiphany to focus her botanical energies on mosses is full of lovely imagery, such as the passage below. 
"Now the miniature forest below her gaze sprang into majestic detail. She felt her breath catch. This was a stupefying kingdom. This was the Amazon jungle as seen from the back of a harpy eagle. She rode her eye above the surprising landscape, following its paths in every direction. Here were rich, abundant valleys filled with tiny trees of braided mermaid hair and minuscule, tangled vines. Here were barely visible tributaries running through that jungle..."
Having done so myself, falling in love with bryophytes is an amazing experience. Upon closer inspection, you realize that there is a world of wonder to explore in miniature. The closer you look the more there is to discover. An adventure that can last a lifetime. 

December 2013 Desktop Calendar

The fact that I have exhausted my moss photos from summer hiking definitely means that I am in need of some outdoor time with plants. Fortunately winter in California means it is possible to see mosses without having to dig them out of the snow. I just wish we had a little more rain to help make them more photogenic. My goal before the holiday break. Find some mosses. Take some photos. 

In the meantime this is another view from our summer hiking in New Hampshire to the top of Mt. Monadnock. From this vantage the trees could be a mossy carpet trailing off into the distance...

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.

The Signature of All Things: Part 1

I read through the first part of The Signature of All Things this past weekend. There is not much to report on the bryological front. Mosses only popped in once or twice. They were used to pack seeds and other plants for transport during long ocean voyages of the 18th and 19th centuries. In this part of the book we are briefly introduced to the main character, Alma, at her birth. Mainly this section focuses on Alma's grandfather, father, and thus her botanical roots.

This book is at the top of my pleasure reading pile. More updates to come after I read through Part 2. 

The Mystery of the Missing Moss

This is a tale of a small group of mosses in the genus Sorapilla. Over the past 150 years they were located by scientists only a handful of times in the wild. That is until recently. A undergraduate student found a population of Sorapilla papuana in Queensland, Australia. 

The real mystery about these mosses is determining its closest relatives. It has a very unique morphology = (exterior size and shape), which has helped researchers come up with hypotheses about its relatives. This new discovery of live mosses means that DNA can be extracted from the plants and used to test these ideas, potentially resolving the conundrum of Sorapilla's relatives.

Honestly I had never known about this genus before hearing about it's recent re-discovery. The article (linked to above) alludes to its unique morphology and I was interested to learn more about it. These mosses grow in tropical regions, so off I went to my Guide to the Bryophytes of Tropical America. To my surprise and delight I discovered that Sorapilla mimics some of my favorite mosses, the Fissidentaceae. 

Both Sorapilla and the Fissidentaceae have leaves in two-ranks, meaning they have a row that runs along the right side of the stem opposite a row that runs down the left side. Most mosses have leaves that spiral around the stem, sticking off in all possible directions. The other cool feature about the leaves is that they are divided into two regions a single layered lamina at the top and a region below where the leaf forks, creating a pocket that clasps the leaf above it. Based on my reading, these are the only two groups of mosses with this type of leaf. Despite these similarities, other features of the sporophyte indicate that Sorapilla and the Fissidentaceae are not closely related. I am really excited to hear what the findings are from the DNA data and which mosses are the closest relatives of Sorapilla. If in the end it is not a close relative of the Fissidentaceae, then it will be another cool example of convergent evolution. Two distantly related species evolving similar morphologies.  

Click here for a link to an image of Sorapilla papuana. 
Not to be confused with sopapillas, the tasty fried pastry.

For comparison, this is a photo of Fissidens that
I took while hiking in the Sierra Nevada Mountains. 

I find it a funny irony that the closest town to the population of the rediscovered moss is called Mossman. It sounds like a town full or moss super heros. MossMan! However, the town name was originally Mosman, so it probably wasn't named for moss plants.  

Hat tip to Dr. Tobias Landberg for sending me the article about this discovery. 

November 2013 Desktop Calendar

Another lovely moss from our summer hike up Mt. Monadnock in New Hampshire. This is the moss Polytrichum commune. Its common name is the hairy-capped moss, named so for its hairy calyptra. Calyptra are the little caps of maternal gametophyte tissue that cover the top of the young offspring sporophytes. These caps prevent water loss from the apex of the developing plant. Think of it as your mother sending you out the door to play with a fuzzy little cap atop your head. However, this cap is meant to keep your wet hair from drying out rather than to keep out the cold. I like to think of it as a reverse shower cap. A little odd to imagine the human equivalent, but it works well by keeping the top of the mosses moist in the dry air. For more on calyptra, check out this summary about my PhD research studying calyptrae. Happy November!

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.

A New Moss Identification Guide

I recently reviewed this new moss field guide for the Botanical Society of America's Plant Science Bulletin. The link below will take you to the Fall 2013 volume. My review is on pages 131 and 132.

Budke JM. 2013. Book Review of Common Mosses of the Northeast and Appalachians. Plant Science Bulletin 59(3): 131-132.

Overall I think that this is a really great text and would highly recommend it for anyone interested in identifying mosses in the northeastern United States and Canada from Wisconsin to Nova Scotia and south throughout the Appalachian Mountains. (Full disclosure: I did receive a free copy of the book when writing this review, but was in no other way compensated.) 

For another perspective, check out this review: Kimmerer, RW. 2013. Field Guide to Northeast Mosses. The Bryologist 116(3):321-322.

In the same volume of the Plant Science Bulletin (pg 137-138) there is a review of the latest book by Amy Stewart The Drunken Botanist: The Plants That Create the World’s Great Drinks. I have one of her earlier books Wicked Plants: The Weed That Killed Lincoln's Mother and Other Botanical Atrocities. I really enjoyed this earlier book and am looking forward to reading the new one! Exploring the plants that are deadly and atrocious is one way to get people interested in plants. Enlightening them about plants used in alcoholic beverages is sure to be another fun way to start thinking about plants. A fact of note: the review of Stewart's book is by Alexandra Boni an undergraduate student from Bucknell University. Kudos to her for writing a nice review of the book. It most certainly has me excited to check it out!

UPDATE - 22 Nov 2013 - Another positive review of this book. Hedenäs, L. 2013. Common Mosses of the Northeast and Appalachians. 173(4): 790–791.

Have you heard of Bogology?

Have you heard of Bogology? Probably not, because I think it is a bit of a newly invented term. Bogology is the study and science of peatlands. I just heard about this new website and blog by researchers from the United Kingdom who are studying peatlands. If you are interested in peat bogs and Sphagnum mosses, the information and discussions they have will be right up your alley.

Thanks to Dr. Kaisa Kajala for making me aware of this site!

The Bryophytes on the Cover

The front cover oElizabeth Gilbert's new novel The Signature of All Things features some lovely bryophyte paintings. They are from the 1905 edition of the German encyclopedia Meyers Konversations-Lexikon. I have not had the pleasure of perusing this encyclopedia, but I do have fond memories of an English version of encyclopedia Britannica. My parents bought a set when I was in elementary school. Black and red cover, crisp glossy pages. Ah, memories. Can you tell I am a bit of a bibliophile? For those of you who have not enjoyed a hardbound encyclopedia set, they were the precursor to google and wikipedia. Want to know something about a fast animal, far-a-way country, historic event, or odd fruit? As my dad would always say, "Go check the encyclopedia." It provided tons of information to answer my pressing questions and constant need to know. Sometimes my sister and I would just sit down with a volume and flip through pages, reading about interesting topics for fun. Did I mention that I grew up in rural Indiana and there weren't a lot of entertainment options?  

Back to the bryophytes of the beautiful image on the cover of The Signature of All Things. In terms of bryophyte identification, there are some complex thalloid liverworts in front with tall antheridiophores and archegoniophores springing up from the ribbons below. Antheridiophores are the male reproductive structures that produce sperm; archegoniophores are the female reproductive structures that make eggs.  On either edge of the cover are mosses with sporophyte capsules elevated on tall stalks. They are most definitely members of the Splachnaceae, the dung moss family. I love saying that name (SP-laCK!-n-ace-a-ee). It has a very dung-y ring to the name! My best guess on a species level identification is Splachnum luteum.  The common names for members of this genus are really great. They include umbrella moss and petticoat moss, which describe the shape of the capsules. I think that petticoat moss is especially fitting for the cover of a book set in Victorian times, about a woman who most likely wore petticoats. 

A New Botanical Heroine

Rarely do female botanists appear as characters in pop culture. Exceptions that I can think of are Poison Ivy from the Batman comics and movies. She was a botanist before becoming a plant-loving super villain. Also there was the horrible movie Paycheck that featured a female botanist as the love interest. This movie sticks in my mind because the portrayal of her 'botany lab' was completely fantastical and laughable.

In comparison, I have much higher hopes for the botanical heroine in Elizabeth Gilbert's new novel The Signature of All Things. Not only is the heroine a botanist, but she is a bryologist! I have heard good things about the book both through reviews in the popular media and fellow bryologists. Fortunately for me I have great friends that indulge my passion for mosses and I was gifted this book for my upcoming birthday. I will keep you posted on my reading progress and any bryological gems that I find!

For more about the book, check out Barbara Kingsolver's review in the New York Times.

Mosses in the Garden

Thinking about integrating some mosses into your garden or landscaping? Have a shady spot that could use a bit of green? Gardening with mosses may be in your future...

Kathy Connolly has written an article on just this topic for The Day newspaper out of New London, CT. I am quoted throughout the article for some tips and moss biology info. Check out the full text for free on their website.

My favorite quote from the article. 
"If you put a philodendron through a blender," says Budke, "you have a dead philodendron. But with moss, each living cell is capable of growing a whole new plant. That's why the blender works." 
This the backyard of the house where I used to live in Connecticut.
Others might call it the 'frog pond' or 'herpetology pool'.
I always thought of it as the "moss pond".
That is just one amazing fun fact about mosses! Each live cell is totipotent. Meaning that each can regrow an entirely new plant and be any type of cell. Similar to stem cells in animals that can be used to grow many different types of organs.

Overall it was a fun interview to give and I think the article came out very well! Informative, interesting, and all about mosses!

October 2013 Desktop Calendar

Pictured here are a few mosses in yellow-green that are surrounded by some complex thalloid liverworts for your October desktop. These are from our hike to the Stebbins Cold Canyon Reserve this past spring. The weather is finally starting to cool down here in the central valley and I am hoping that we will get out for a few more hikes while the weather is lovely and comfortable. Happy botanizing!

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.

Rare Mosses and Liverworts of England

It has been a full week with little time for me to work up my own blog post. Instead I encourage you to check out a post over on the IAB blog by a bryological colleague, Juan Carlos Villarreal. It is a book review of a new text focusing on rare mosses and liverworts of England. He gives you the highlights of the book and includes the details of one rare moss species Telaranea murphyae Paton. Enjoy!

Two Structures, One Set of Genes

When presented with a problem it is typically easier to solve it with tools at your disposal rather than inventing something new. This is also the case for plants and animals. When presented with a developmental or evolutionary challenge, it is often easier for them to use genes that already exist in their genetic toolkit to respond to the challenge.

Rhizoids are thin filaments of cells that anchor leafy moss plants onto their growth surface, which can be soil, rock, or trees, just to name a few. Rhizoids also function in water uptake. They help by creating many capillary spaces in which water can be move from the soil to the plant. However, rhizoids are not the only structures that are able to take up water in mosses. The leafy gametophyte plants can absorb water through many parts of their body including leaves and stems. 

The water uptake structures that you are probably more familiar with are roots. They are underground organs that function in water uptake and anchor the sporophytes of vascular plants into the soil. Near the tips of each root there are elongated, filamentous cells (root hairs) that increase the surface area through which the roots can take in water. 

Though root hairs and rhizoids have similar functions and they both start with the letter 'R', these two structures have completely independent evolutionary origins. By that I mean that root hairs are not rhizoids that have been changed and modified over evolutionary time. Another piece of evidence that points to them being evolutionary independent is that rhizoids are only present on the gametophytes, whereas root hairs are only on the sporophytes. Having structures that are exclusive to opposite generations typically indicates that have evolved independently. 

So, root hairs and rhizoids have similar functions, structurally they are both filamentous in shape, but what about the genes that control their development. Might they be using the same or similar parts of their genetic toolkit to build these two structures? 

Scientists examined this by figuring out the genes that are important for forming the root hairs in flowering plants, then looking to see if these same genes are also important for root hairs in mosses (Menand et al 2007; Pires et al 2013). The figure below shows some of their results. Let me walk you through it. On the left are mosses will brown rhizoids growing from the base. On the right are flowering plant roots with thin root hairs sticking out of the sides. WT and Col0 are what the plants look like naturally with no changes to the genes. 

Part of Figure 4 from Menand et al 2007

They found a group of related genes in mosses and flowering plants that influence both rhizoid and root hair formation. Pprsl1, Pprsl2, and rhd6-3 are the names of three members of this group of genes. 

What we see on the left is that they knockout/turn off Pprsl1 = rhizoids still formthey knockout/turn off Pprsl2 rhizoids still formbut when they turn both of them off  = no to only a few rhizoids form. 

On the left, center panel they turn off the gene rhd6-3 and the root does not make any root hairs. The coolest part of the study is that they are able to knock out the gene that makes root hairs, then use the moss gene to control the formation of root hairs. They are using a moss gene to control the production of root hairs in a flowering plant. Pretty wild!

This is just a small part of the story where they show that root hairs and rhizoids are controlled by the same network of genes. I think that it is a great example of plants using the genetic tools at their disposal to build similar structures on completely different parts of the plant in distantly related species. 

Check out the publications for more details about their experiments and findings. 

ResearchBlogging.orgMenand B, Yi K, Jouannic S, Hoffmann L, Ryan E, Linstead P, Schaefer DG, &; Dolan L (2007). An ancient mechanism controls the development of cells with a rooting function in land plants. Science (New York, N.Y.), 316 (5830), 1477-80 PMID: 17556585

Pires ND, Yi K, Breuninger H, Catarino B, Menand B, &; Dolan L (2013). Recruitment and remodeling of an ancient gene regulatory network during land plant evolution. Proceedings of the National Academy of Sciences of the United States of America, 110 (23), 9571-6 PMID: 23690618

Do you have Pteridomania?

On the title page of her book Fern Fever: The Story of Pteridomania Sarah Whittingham informs us of the following definitions.
"Pteris Greek word for a fern, derived from pteron, meaning feather or wing. Pteridophytes The ferns and fern allies. Pteridologist One who studies ferns scientifically. Pteridomania Fern madness. Pteridomaniac One who suffers fern madness."
I just started exploring this book written about the Victorian obsession with ferns. It is a large coffee-table sized book with a myriad of color images and photos of all things fern. The introduction covers how the fern craze began in the 1850's with collectors traveling the world and sending ferns back to England for cultivation. With the invention of the Wardian case, a small terrarium, ferns were brought into people's homes. At the same time many authors were publishing books about growing ferns and the types of ferns native to Britain. Naturalist and gardeners alike could not get enough of them. Ferns even made it into fashion as a design embellishment on dresses. 

I think that it is going to be a fun and educational read. I would recommend it for anyone who is already obsessed with ferns or would like to join in the craze. It will also be appealing to the history-minded and lovers of the Victorian era.   

At this time, science was the realm of mostly learned, wealthy white men. Women with botanical interests, also white and wealthy, collected, drew, and dried plant specimens under the purview of a gentle hobby. They knew little about how ferns reproduced. One fantastical idea was that they flowered only once per year and the spores could only be collected at night. Around the same time Wilhelm Hofmeister was just publishing his findings on the alternation of generations and plant life cycles. Interesting to think how far science has come both in our knowledge about plants and increased inclusiveness of people from diverse backgrounds. 

I leave you with a poem that Sarah Whittingham includes in her book on page 40. I especially like it because it contains a shout-out to my favorite ferny friends, the mosses.  

Auld Botany Been was wont to jog
Thro' rotten slough and quagmire bog 
O'er brimful dykes and marshes dank, 
Where Jack o' Lanterns play and prank,   
To seek a cryptogameous store 
Of mosses and carex and fungus hoare, 
Of ferns and brakes and such-like sights
 As tempt out scientific weights
On winter's day; but most his joy
Was finding what's called Osman's Roy.
- Plues A Summer Study of Ferns  

September 2013 Desktop Calendar

This image from one of our hikes in South Tahoe last month. We started at the end of a tiny windy road that ran along Fallen Leaf Lake and hiked up to Gilmore Lake. These Polytrichum mosses were growing along the edge of the lake. They make for a very busy image. So busy that it is a little challenging to see the calendar. Hopefully your September is not nearly as busy as this photo!

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.

Mosses Winning Awards

Summer science conferences are in full swing and I am happy to report that our moss research has won some awards at two recent conferences!

Luke Busta presented our collaborative research studying cuticle waxes on mosses at the Phytochemical Society of America meeting. The cuticle is a layer of waxes and polymers that cover the surface of plants and prevents water loss. Luke is a chemistry graduate student in Dr. Reinhard Jetter's lab at the University of British Columbia. His talk, entitled "Cuticular waxes from the gametophyte, sporophyte, and calyptra of the moss Funaria hygrometrica" won the best student presentation at the meeting. This was his first national meeting and is a fabulous accomplishment!

I attended the Botanical Society of America meeting a couple of weeks back and one of my research publications from my PhD (citation below) won the Grady L. Webster award. This award is given for the "most outstanding paper published in the American Journal of Botany in the field of structural and developmental botany (i.e., anatomy and morphology) over the two-year period prior to the award year". I feel very honored receiving this award. As a scientist I publish my findings in research journals and people in my sub-field read them and then refer to/cite them in their own papers. In spite of getting the work out there for people to read, scientists rarely get direct feedback on what others think of their work. It is great to know that my scientific research is well-regarded by other botanists. 

Budke JM, Goffinet B, Jones CS. 2012. The cuticle on the gametophyte calyptra matures before the sporophyte cuticle in the moss Funaria hygrometrica (Funariaceae). AmericanJournal of Botany 99: 14-22.

Sharing these positive events here on the blog was inspired by reading this article on the Scientific American blog about academic life. One of her recommendations was to start a "feel good" email folder to remind yourself of kind words others have shared and happy successes to help you make it through tough times. These awards are headed to my "feel good" folder and I wanted to share them here too. Writing this blog has definitely had a positive influence on my professional life. It helps me stay focused on the interesting aspects of moss plant biology and allows me to share my thoughts on the latest science research on mosses. Thanks!

August 2013 Desktop Calendar

Two weeks ago I was in New Orleans for the Botany 2013 meeting, this past week I took some vacation time to do some hiking in New Hampshire, and this upcoming week I am off to a Plant Development meeting in Vermont. It has been a whirl-wind time reconnecting with colleagues, friends, and family. Apologies that the August desktop calendar is a little late. Hopefully you have been enjoying the summer weather and calendars have been far from your mind.

The image below shows some Sphagnum mosses with capsules. I took it on our hike up Mount Monadnock in New Hampshire. It was a good hike and really great to see so much lush summer vegetation!

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.

Exploring Calyptra Function: A dissertation saga in summary

In mosses, the calyptra is a small cap of maternal tissue (1N - gamtophyte) that covers the top of the offspring (2N - sporophyte) during development. A long-held old hypothesis (from 1884!) is that the calyptra prevents the underlying tissues of the sporophyte from drying out. Think of it this way, the top of the moss offspring is made of young tissues that are sensitive to drying out. The idea is that the maternal plant provides a little cap on the top of its offspring to keep it safe from the harsh, cruel world. Similar to a mother sending her kids out to play in the snow with fuzzy hats to keep them warm. However, the idea with the calyptra is that it is a reverse shower cap, envision a old-fashioned shower cap keeping the water off your grandmother's perm, but rather than keeping the water out, it traps the water inside. With this little cap the apex is kept moist and can finish developing.

So this is a great idea and I have told you a nice tale, but this is a science blog and you came here for some evidence based findings, did you not. My PhD research focused on the hypothesis/idea that the function of the maternal moss calyptra is to prevent the apex/top of the offspring sporophyte from drying out as it grows and matures. 

Below are the highlights of my findings and how they connect to the examination of this hypothesis. Check out the figures and the summary statements in bold if you only have a moment. 

First the study organism - This is the moss Funaria hygrometrica, commonly called the cord moss. It is a plant that can be grown in the laboratory and is great for using in experiments.

Figure 1 from Budke et al. 2011 - Funaria hygrometrica
A. Moss sporophyte offspring.
B. Single sporophyte with calyptra on the top.
C. Small sporophyte covered by maternal calyptra.  

My first step was to examine the calyptra to look for features that would help in protection against dehydration. Plants are covered by an external layer of waxes and polymers (the plant cuticle) that prevents water loss from their bodies. I measured the thickness of the cuticle layers on two regions of the calyptra (rostrum, inflated base), the sporophyte, and leafy gametophyte (results in Figure 2).

Figure 2 from Budke et al. 2011
Cuticle thickness quantified

The cuticle covering the calyptra (both the rostrum and inflated base) are thicker than the cuticle on the leafy gametophyte and sporophyte. I also discovered that the calyptra rostrum has cuticular pegs, specialized cuticle thickenings that reinforce the cuticle in regions where the cells come together and may be leakier. These pegs were not found on any of the other structures that I examined. Both thicker cuticle layers and the presence of pegs are evidence supporting the hypothesis that the calyptra has a specialized cuticle that functions in preventing dehydration of the sporophyte apex. 

Budke JM, B Goffinet, and CS Jones. 2011. A hundred-year-old question: is the moss calyptra covered by a cuticle? A case study of Funaria hygrometrica. Annals of Botany 107: 1259-1277.

Part 1 summary - The calyptra has waxy layers that are significantly thicker than the leafy parts of the maternal plant, supporting the hypothesis that it is specialized structurally for preventing water loss. 

My second step was to examine the waxy cuticle (developmentally) to determine when the calyptra cuticle reaches maturity. I predicted that early during development the young sporophyte would have a thin cuticle and thus need protection from drying out. If the calyptra is providing protection, then I predicted that its cuticle would reach maturity early. Check out the figure to see how the moss changes size and shape during development. They start out so small, only a couple of millimeters tall, fractions of an inch.

Figure 1 from Budke et al. 2012
Moss sporophytes at nine developmental stages. 

All scale bars = 1 millimeter

  So I sliced and diced both calyptra and sporophytes at 9 different ages from young to old to figure out when the waxy cuticle develops on both the maternal calyptra and the offspring sporophyte. I found that all 4 layers of the calyptra cuticle were fully developed and thick at the earliest developmental stage, whereas the sporophyte is only covered by 1 or 2 thin layers at early developmental stages. Only later is the sporphyte covered by 4 thicker layers.

Figure 7 Budke et al. 2012
Diagram showing the four cuticle layers
present on the calyptra (c) at all 9 stages
and the wave of layers that are added
from the bottom to the top as the
offspring sporophyte (s) expands.

At early stages the maternal cap is fully protective with all 4 layers, whereas the sporophyte is covered by only 1 or 2 layers when young. This supports the idea that the calyptra is providing protection and the sporophyte requires protection. 

Part 2 summary - The calyptra is covered by four, thick cuticle layers at all developmental stages. The sporophyte is covered by only 1 or 2 layers early and more layers do not develop until later. This evidence supports the hypothesis that the maternal calyptra has the structural ability to protect the offspring sporophyte when it is young.  

Budke JM, B Goffinet, and CS Jones. 2012. The cuticle on the gametophyte calyptra matures before the sporophyte cuticle in the moss Funaria hygrometrica (Funariaceae). American Journal of Botany 99: 14-22.

Fig 5 Budke et al. 2013
A. Cuticle showing all layers present.
B. Cuticle after experimental removal of outer layer.
My third step was to carry out an experiment that tested the dehydration hypothesis to see if the waxy layers of the maternal calyptra are really necessary for sporophyte offspring success. I experimentally removed the waxy layers of the calyptra (a challenging task since all of the moss bits are so small) and then exposed the plants to a stressful dehydration event. This experiment showed that without the waxy cuticle on the calyptra sporophytes had lower levels of survival, they developed slower, and produced fewer spores per capsule. Some of them were even malformed and unable to open to release the spores. Remember that the spores are the part of the life cycle that disperses on the wind and arrives new places for the mosses to grow.

Part 3 summary - Under dry conditions, without the waxy layers, the maternal  calyptra is unable to protect the offspring sporophyte. Without the protective calyptra they are negatively affected. Fewer survive and they make fewer spores per capsule. This is another piece of evidence supporting the hypothesis that the maternal gametophyte calyptra is critical for protecting the offspring sporophyte from dehydration. 

Budke JM, B Goffinet, and CS Jones. 2013. Dehydration protection provided by a maternal cuticle improves offspring fitness in the moss Funaria hygrometrica. Annals of Botany 111: 781-789.

After my research we now have the scientific evidence to support the idea that the maternal moss calyptra is functioning to prevent the top of the young sporophyte offspring from drying out. No longer just a tale or hypothesis alone, there is now evidence to back up these ideas!

Stay tuned for additional parts of the calyptra story. I am working on a review paper summarizing and discussing the historical literature and experiments that focus on the moss calyptra and its function. Also, I am studying the calyptra cuticle comparatively in species that have small and large calyptra and small and large sporophytes.

July 2013 Desktop Calendar

This is the moss Grimmia trichophylla. It is a scrappy little moss that often grows on rocks. I found this one while hiking out on an exposed boulder in the coast range of California. 

I am in the process of setting up my new microscopes and camera so that I can take some mossy photos from home. I tried getting a shot of this moss under the microscope, but I am still working on adjusting the settings just right. Thus there are two calendar options for July. 

Grimmia trichophylla growing on a rock.

Grimmia through the microscope. 

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.

For your curiosity, this is what the mosses look like growing on the rock in the field. They are definitely not the most charismatic species and you might miss them if quickly hiking by, but with some magnification they reveal leaves topped by white spiky hair points and sporophytes mixed in that change direction with water. Now I just have to figure out how to capture their motion in action.   

Parent Child Relationships continued...

The calyptra is a cap of maternal gametophyte tissue that covers the apex of the offspring sporophyte during development. My research shows that in the calyptra has a waxy cuticle that develops early and prevents water loss from the underlying sporophyte tissues. I think about this as the maternal gametophyte investing in these protective layers to keep the sporophyte safe from the harsh conditions of drying out as it grows taller and taller. 

This figure illustrates the maternal gametophyte calyptra
and its location across the stages of sporophyte development. 

An additional interpretation is presented by Haig. He views the waxy layers on the calyptra as slowing down or preventing the sporophyte from pulling up more water and potentially nutrients from the maternal plant.
 Haig, D. (2012). Filial mistletoes: the functional morphology of moss sporophytes Annals of Botany, 111 (3), 337-345 DOI: 10.1093/aob/mcs295

These differing interpretations of the same phenomenon are not mutually exclusive. One is not right and the other is wrong. As Haig mentions, both maternal protection and restraint are likely to be occurring at the same time. This relationship between mothers and their offspring is a phenomenon that is seen across the plant and animal kingdoms.