Field of Science

Showing posts with label Atrichum. Show all posts
Showing posts with label Atrichum. Show all posts

Persistent P's Permeating the Polytrichiaceae

In lab group last week we read an article about the moss family Polytrichiaceae. These are the mosses that have fabulous little lamellae on their leaves. Some species are quite common and can be found in open disturbed edge habitat. They can be recognized by their star-shaped form when viewed from above and they are often one of the largest mosses that you will see in the field.


Bell, Neil E. and Jaakko Hyvönen. 2010. Phylogeny of the moss class Polytrichopsida (BRYOPHYTA): Generic-level structure and incongruent gene trees. Molecular Phylogenetics and Evolution 55: 381-398. 

Species are typically grouped into the larger category of genera based on the morphology of the plants, their physical appearance. Thus all the members of the genus Atrichum (the smooth capped mosses) look similar to each other and the same for other genera such as Polytrichum (the hairy capped moss). Sometimes it ends up that these morphological groupings are confirmed by the DNA sequence data and all the members of the genus did descend from a common ancestor. Other times the DNA data shows that the members are not descended from a recent common ancestor and are instead distantly related. The morphology and the DNA evidence tell a different story. In this study both Polytrichastrum and Oligotrichum are composed of members that are distantly related. The later genus has a distinct geographic pattern with all the northern members being related to each other and all the southern members in the other group. Overall I think that it is pretty cool to explore these morphological hypotheses with DNA data. You never know what there is to be found. 

Another paper on this group of mosses by the same authors.
Bell, Neil E. and Jaakko Hyvönen. 2010 A phylogenetic circumscription of Polytrichastrum (Polytrichaceae): Reassessment of sporophyte morphology supports molecular phylogeny. American Journal of Botany 97: 566-578. 

My Bryology Bookshelf - III

Mosses With A Hand Lens by A. J. Grout 
Third Edition - 1924
A Popular Guide to the Common or Conspicuous Mosses and Liverworts of the North-Eastern United States

In my search for a field guide to the mosses of New England, I came across this book at my university library. I then purchased my own copy to add to my reference shelf. You can check out the entire book here online at GoogleBooks.

Some great aspects of this book are that it is meant to be used with a hand lens. Other books require either a dissecting or compound microscope. The initial dichotomous key is a manageable length with 25 couplets. Then it spits into Acrocarpous and Pleurocarpous mosses that then have a 36 and 14 couplet key respectively. The line drawings are really well done and are quite informative for species identification. The photographs are ok, especially considering they are from 1924, but are pretty grainy and black & white. The diagrams for the liverworts are typically much smaller and with less detail. This may show a bias of the author toward the mosses.

Since the book is quite old some of the names of the genera are out of date. But it is interesting historically to see how the scientific names have changed from then to now.
Catharinea is now Atrichum
Webera is now Diphyscium
Georgia is now Tetraphis

Another interesting finding in this book is that hornworts are described as a specific type of liverwort. They are classified in the family Anthocerotaceae, The Horned Liverworts. Currently the hornworts are classified as a distinct lineage separate from the liverworts. Thus there are three main groups of Bryophytes; Mosses, Liverworts and Hornworts. I am not sure when hornworts were moved to their own lineage. Sometime between 1924 and now? This is a question for my lab-mate Juan Carlos. I will let you know what he says when I see him tomorrow.   
 

Salt-Shaker Spore Dispersal

Mosses in the Polytrichaceae spread their spores in a really neat way. Shown here are Atrichum sporophytes. Another member of the family that I have blogged about is Polytrichum, which also shares this dispersal mechanism.

Atrichum's manner of spores dispersal has been described as a salt shaker mechanism. And as you can see on the up-close shot below, it is a pretty good analogy. The mouth of the capsule is surrounded by a ring of short, immovable teeth that attach to a disc covering the opening to the capsule. The disc keeps rain from entering the capsule so that the spores do not start to grow before they have exited the capsule. When a breeze or a passing animal jostles the capsule the spores sift out from between the teeth. This mechanism also keeps the spores from coming out in a single mass, which would pretty much defeat the ability of these spores to spread on the wind.

If you are ever out in the woods and see some Artichum (or Polytrichum) sporophytes, give them a tap. You may be rewarded by a poof of spores emanating from the top of the capsule.

Fun Fact: Spores are so small and light that they can disperse very long distances. Researchers carried out a study (I am not sure of the reference off the top of my head, but I will check.) where they attached sticky microscope slides to the wings of a plane that flew high into the air. What do you know, they found moss spores all the way up in the the jet-stream. Pretty cool that they are able to travel that far up and then far away!

Off to Study Mosses in Japan

Well this is my last day in Connecticut before heading off to Japan tomorrow. My laundry is done, the lab is tidy, and some of my fabulous fellow graduate students will be taking care of my mosses here in Connecticut while I am gone. I still have a full day ahead of me with packing and cleaning my apartment, but the anxiety about the trip is starting to fade away and I am finally getting excited about the whole adventure.

One of the items that is quite important when meeting people professionally in Japan are business cards. Thy are called meishi in Japan. There is a formal method of meishi exchange that includes bowing. Here is a link to the entire story regarding meishi exchange. Hopefully I will not completely botch the exchange process and I can avoid embarassment.

Of course the business cards that I ordered got tied up in the printing and shipping process and will not arrive before I leave. Hopefully I will be able to have them sent to me so that I can use them while I am there.

I have posted versions of my business card in english and the one the my Japanese research advisor translated into english. The translation is pretty rough. Looking up Japanese characters is not easy. It says Connecticut University Ecology and Evolutionary Biology on the first line. Doctoral University student on the second line. The third line is my name. The prevaling comment that I have gotten is that it is pretty fun that my name in Japanese has two smiley faces. : ) The following lines are my contact information at the National Institute for Basic Biology.

On the at home front, the moss walk this past Saturday went well. We had six participants who came on the walk. We didn't walk very far, which is usually the case when looking at mosses, but everyone had a good time. Since everyone on the walk was new to mosses I introduced several of the common genera that can be found in Connecticut.

Atrichum Hypnum Leucobryum Polytrichum Plagiomnium Sphagnum

Well that is all for now and I will next be posting from Japan. Wish me luck.

The Common Names of Atrichum

Mosses in the genus Atrichum have a couple of common names, as many plants do. One name is the smoothcap moss. As I mentioned in last week's post, this name describes the lack of hairs on the calyptra of Atrichum, which is contrast to the hairy calyptra of Polytrichum (the hairy capped moss).

The other common name for Atrichum mosses is the catherinea moss. Originally the genus name for this moss was Catherinea. This name was given to these mosses in honor of Catherine II, who was the Empress of Russia from 1762 to 1796. Historically botanists named plants in honor of their wealthy patrons who funded their research. This genus was named by the German botanist Jakob Friedrich Ehrhart. He was a student of Linnaeus, the famous scientist who came up with the system of binomial nomenclature (Genus species).

Another Moss with Snorkels

WARNING: This information is inaccutate. Please see this more recent post for additional information.


Atrichum is in the moss family Polytrichaceae, which also contains the genus Polytrichum. This genus is similar to Atrichum in that they both have lamellae (aka. moss snorkels) on their leaves. The difference is that the lamellae in Polytrichum cover the entire surface of the leaf, whereas in Atrichum there are fewer lamellae per leaf (around 1-9) and they are located only on the midrib. The photo to the right is of a cross-section through a leaf that has four lamellae on the thickened midrib.

These lamellae are composed of a single file of green photosynthetic cells. They function by sticking out above the film of water that covers the plant to provide a dry surface for gas exchange. These lamellae can be seen with a hand lens as lines running along the surface of the leaf. The distribution of these snorkels are unique to Atrichum and are a good feature to use to recognize the genus.

Easter Moss

My advisor's daughter left us some Easter goodies in the laboratory over the weekend. Sitting in our office fridge was this cute little bunny. It is filled with some gametophytes and sporophytes of the moss Atrichum. It is a common genus in Connecticut that can be found growing on disturbed soils such as road-banks.

This is in the moss family Polytrichaceae, which also contains the genus Polytrichum. The names of these two genera have an interesting relationship. Polytrichum ca be broken down in to its component parts. Poly- is a prefix derived from Greek that means much or many. The second half of the word is also of Greek origin. -trichum refers to a hair, thread, or filament, hence the common name is the hairy capped moss. Atrichum also has a cap, or calyptra, on its sporophyte (not pictured here). However its calyptra is entirely hairless, thus the prefix a- means not or without. So this genus is without hairs on the calyptra. Isn't it great when the scientific name of an organism has meaning and relates to its morphology (exterior physical appearance).