Identifying Mosses with Only a Photo

A friend of a friend sent me these lovely photos of mosses from Bath, England to identify. 

So, where do we start? Well, I usually start with the features that look the most distinctive and sift through my mental card catalog of mosses to see which ones these fit. Sporophytes can be helpful for determining the higher classification for the moss, such as the order or family. 

1) The peristome teeth look to be made of many narrow filaments that are twisted at the apex, which = Pottiaceae in my mind.

Now we get to the more difficult part of moss identification. Trying to get lower than family or genus from just a couple photographs. What else can we see.

2) The leaves are topped by long, white awns.

3) Some of the leaves are folded inward. 

4) It is growing on rock or concrete. 

My tendency is to go with a common species that doesn't contradict the observations we can make from the photos. So my initial thought for this one is Syntrichia ruralis, but that is a species I know from North America and we know this photo was taken in England. 

So, does Syntrichia ruralis grow in England or do they have different Syntrichia species we should consider?

Off to the British Bryological Society's Online Field Guide. 

They have 13 species/subspecies of Syntrichia listed.

{With additional clicking there are actually only links to pages for 7 species/subspecies.}

They have two subspecies of Syntrichia, but both of them say that capsules on this species are rare. And this specimen has a lot of capsules. So I'll flip through some of the species and see which ones match. They also have great maps in the corner so I pulled up the location of Bath to see if that would help narrow the search.  

There are a few that look close, but none that give me that gut feeling of yes we have a match. The awns in the descriptions/drawings seem too short compared to the photos. They look to be at least 1/2 the length of the leaf lamina in the photos. So let's take a step back. A lot of the Syntrichia species were formerly in the genus Tortula, which is also in the Pottiaceae. Let's take a look at some of the species in that genus. 

Most of the Tortula species have small awns or are lacking them, except for Tortula muralis. 
Check the description of this species out to see what you think compared to the photos.

Long awn - Common species growing on mortared walls - Distribution covers Bath 
Nothing from the description is in contradiction to what I can see from the photos. It also points out that Syntrichia species are often larger and the photos look smaller, more similar to the Tortula in size.  

I think we have a winner! Tortula muralis is my ID for this species based on the photos and the British Field Guide.

What do you think? Would you give it a different name?

May 2014 Desktop Calendar

This is another moss from my March trip to Yosemite National Park. Since I found it in a park, I don't have collection to help with the identification and it doesn't look like a species I encountered on the SOBEFREE foray. Thus I don't have an identification for this spectacular little plant. 

Does it look familiar to anyone? A pleurocarpous moss growing on granite in the Sierra Nevada mountains. If you have a guess please share it in the comments section. Thanks!

May Desktop Calendar

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 Video on the Moss Life Cycle

Take a break from your regularly scheduled program to check out this video on the moss life cycle. I would definitely recommend this video to students learning about mosses or bryophytes in class or for anyone who wants to brush up on their plant life cycles.

Overall I think that it is a nice video with accurate information. There was only one typo that I saw. The maternal gametophyte cap covering the sporophyte apex during its development is called the calyptra. No e after the t. 

Hat tip to Dr. Juan Carlos Villarreal for sending me this video from YouTube. 

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.

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.

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.

Is the plural Calyptrae or Calyptras?

The moss calyptra is a small cap of gametophyte tissue that covers the apex of the moss sporophyte during its development. This little structure was the focus of my dissertation. Below is part of a figure that I used in my defense showing calyptra from several different moss species. The calyptrae are indicated by the orange arrows

 

This discussion may seem (ok) is pretty esoteric, but a reviewer on my last manuscript brought up this question. They proposed using calyptras as the plural of calyptra, rather than calyptrae. (Yes, these are the things that I think about for my job.)

This is part of the reviewer response that I sent to the editors regarding this question.

We agree that there are challenges when adopting terms into other languages especially concerning the plural form of the word. The term calyptra is derived from the Greek word kalyptra, meaning veil or hood. The plural for the Greek word kalyptra is kalyptrai. However, with the change in spelling and its use in other languages the term has been latinized. Often Greek plurals ending in –ai are transformed into –ae (e.g., mycorrhizae, cypselae, thecae). Perhaps this was originally a spelling error, but at least in terms of the moss calyptra the –ae ending has persisted. In the two most widely used bryological glossaries (see references below) the plural form is cited as calyptrae and many papers and books use this plural form. I do not think that retaining this traditionally used plural form makes the study any less accessible to non-bryologists as there are other botanical terms that have similar plural forms. Thus, we would prefer to continue to use calyptrae as the plural form in our manuscript. Additionally, switching to an –s ending would require additional explanation, which is outside of the manuscript’s focus.

- Magill, RE. 1990. Glossarium polyglottum bryologiae: A multilingual glossary for bryology. Missouri Botanical Garden.

- Malcolm, B and N Malcolm. 2000. Mosses and other bryophytes an illustrated glossary. Micro-Optics Press.

Thanks to my colleague Nic Tippery who contributed to this explanation and I consult on all words Greek and Latin.

The Tree Moss Climacium

This is a really cool moss that often grows in seepy, shady areas next to standing pools of water or streams. It's common name, tree moss, comes from the growth form of its leafy gametophyte, which resembling a tiny tree. Due to its tree-like appearance these plants have been used as the trees in model train displays. I have also heard that they were used as decorations in ladies hats.
 

Shown here is the species Climacium dendroides. I took some photos and wanted to share them because this is the first time that I have seen this species with sporophytes, and thus the first time that I have seen their calyptrae.

The calyptra (shown on the left) is pale yellow, smooth, and cucullate (splitting up a single side upon capsule expansion). I wanted to section some of them to look at their cuticle, but I lost this one. Then when I went back to the population that was collected for DNA extraction in the lab I found that all the calyptrae and sporophytes had already been used for a massive DNA extraction. Too bad. It would have been cool to get a look at their calyptrae using the electron microscope. 

A really spectacular feature of the sporophytes are their peristome teeth! The exostome (outer ring of teeth) are deep brown-red in color. They contrast well with the endostome (inner ring of segments) that are golden brown. The inner teeth are longer and when dry the outer teeth curve inward, as shown in the image below.

The genus name Climacium, comes from the Greek word klimax, which means ladder. The researchers who named this genus thought that the endostome had the appearance of a ladder. I think that it is a pretty accurate description. However, one would have to be tardigrade-sized to use them as a ladder!

Keep an eye peeled for this species if you are in deciduous forests that have some wet areas. I see the gametophytes regularly in Connecticut and seeing some sporophytes is definitely a treat!