Mosses
April 28, 2008
Rhizomnium glabrescens
Well, I've managed to wrest Connor away from his exams for a bit. He's the author of today's write-up. Along with diving into today's write-up, I also suggest you visit Berry-Go-Round #4 at Foothills Fancies weblog. Berry-Go-Round is a weblog carnival devoted to plants.
Connor writes:
Many thanks to Michelle Fitterer for today's photograph.
Rhizomnium glabrescens is a moss that can easily be found in the Nitobe Memorial Garden. It forms a dense, shiny turf under the coverage of the garden's tiny forest. In Some Common Mosses of Birtish Columbia, W.B. Schofield reports that Rhizomium glabrescens is limited to western North America from California to Alaska and as far west as Montana.
The most striking features of this moss can be seen from this photograph. The leaves are a pale green colour with a pronounced costa, a central midrib of specialized cells. The costa is made up of a central conducting strand and thick-walled cells called stereids. The central conducting strand functions as a water transport and the stereids provide support for the leaf.
The leaf margin is also well differentiated. Marginal cells are elongate, lack chloroplasts, and are found in multiple layers (multistratose), while the rest of the leaf blade contains chloroplasts and is only one cell layer thick (unistratose). The UBC Biology 321 website provides excellent images of Rhizomnium glabrescens.
The male plants of Rhizomnium glabrescens possess a rosette of leaves making up the perigonial head. The dark cluster in the centre are many antheridia with paraphyses, sterile filaments of cells. Inside the antheridia, mobile sperm with flagellae are produced. The perigonial head acts as a splash cup, increasing the sperm's dispersal distance when a raindrop falls on it.
Posted by Daniel Mosquin at 4:02 PM| Comments (3)
February 27, 2008
Tortula muralis
Connor Fitzpatrick is responsible for today's write-up:
This bryophyte (liverworts, hornworts and mosses), belongs to the class Bryopsida. Also referred to as the joint-toothed mosses, the Bryopsida account for 95% of all moss species. The common name refers to the fact that the peristome teeth found on the sporangium of these mosses are made from fragments of whole cells. The peristome teeth of this moss are hidden underneath a calyptra and an operculum. The UBC Biology 321 course website does an excellent job explaining moss morphology.
This particular moss, Tortula muralis, has a wide distribution and can be found on all but one continent. This incredible range is due in part to an ability to tolerate desiccation (water loss). Eric in SF@Flickr noted that he found this moss growing on a brick wall. As Daniel mentioned in a previous BPotD posting, ectohydric mosses such as Tortula muralis rely on external water conduction. Mosses are in constant equilibrium with their habitat. Water is travelling in and out of cells depending on the available moisture in the environment, a condition known as poikilohydry. Several physical features help this moss retain water in low-moisture environments (such as brick walls), including leaf extensions (awns) which reflect light & increase the laminar boundary layer and very dense, short growth. Another bryid moss that can be found on similar substrates and shares these features with Tortula muralis is Grimmia pulvinata. The ability to resist desiccation at the cellular level is an active area of research. Oliver et al. (PDF), compares the mechanisms of desiccation tolerance in bryophytes to those of vascular plants with the hopes of coming to a better understanding of the evolution of this ability throughout land plants. One such mechanism (PDF) found in the moss Tortula ruralis (not a typo), is the conservation of polyribosomes during desiccation. Polyribosomes are needed for the translation of mRNA into proteins. Upon rehydration, these conserved polyribosomes allow the moss to resume protein synthesis.
An understanding of the processes employed by mosses and vascular plants to “cope with severe water deficits has economic and agricultural implications that directly relate to crop productivity in an ever challenging and changing environment” (via Oliver et al.). Thank you to Eric in SF for a very interesting photograph (original via BPotD Flickr group pool).
Posted by Daniel Mosquin at 12:00 AM| Comments (13)
October 26, 2007
Unidentified Moss
Apparently, identifying the species of moss residing on top of a rock in the middle of a river is quite difficult. I put in a call to one of the local moss experts explaining my photograph, naively thinking that there can't be that many species of mosses living on stream-rocks. It turns out that there can be that many. Similar to terrestrial species of moss, a good macro photograph with fruiting structures (or even better, a specimen in hand) is required to take a stab at identification.
This photograph was taken in-camera and processed a bit less than I normally do. The effect of the water is due to a specialized glass filter and long exposure.
Posted by Daniel Mosquin at 7:14 AM| Comments (10)
October 6, 2007
Skagit Valley Provincial Park
I made my annual trek yesterday to view the autumn colours (particularly Acer circinatum) in Manning Provincial Park and the adjacent Skagit Valley Provincial Park. In my opinion, the colours were average or a bit better along the Highway 3 roadside, so not as spectacular as the previous two years. On the hiking trail I went on, though, the colours were non-existent to below par. Admittedly, the trails don't seem to be as good as the highway roadside for colour, but the trails have the distinct advantage of being away from wind-causing, noisy highway traffic.
After a brief bit of disappointment regarding the maples, I mentally switched gears and started to photograph other things, like this scene from the Skagit River trail. There are two or three spots along the first 6km (3.75 miles) of the trail where the floor of the forest is dominated by the moss shown here, Hylocomium splendens for stretches of 50m (160feet) or so. Invariably, these are areas shaded by coniferous trees and therefore with acidic soils, but that combination of factors is present elsewhere along the trail where the moss isn't found in such quantity. So why only in these brief stretches? I don't know. If forced to make a guess, I would suggest two possible reasons (or a combination thereof): marginally increased local humidity or that this is a successional stage in the re-establishment of plants after a rock and mud slump. The latter strikes me as a good possibility; the ground beneath the thick layer of moss was quite rocky and, after the heavy rains of last year, a new rock and mud slump occurred elsewhere along the trail — approximately 50m wide!
From the Bryophyte Flora of North America entry for Hylocomium splendens, we learn that stair-step moss or stepped feathermoss is “one of the most common and widespread mosses of the circumboreal forest and Arctic tundra, which covers huge areas of Alaska, Canada, northern Europe, and Siberia” and also present in northern Africa, Australia and New Zealand. To view more photographs of Hylocomium splendens, visit the Bryophytes of North America photo gallery or the Northern Ontario Plant Database (the latter has a description of the moss and more resource links.
Posted by Daniel Mosquin at 7:20 AM| Comments (9)
May 1, 2007
Dawsonia longifolia
Thank you to Eric in SF@Flickr for sharing another photograph from Borneo (original | BPotD Flickr Group Pool). This photo is one of over 150 photographs in Eric's Borneo: All Other Plants, Flowers and Bugs photo set. Always appreciated, Eric.
What's particularly special about this moss is its freestanding height (and what that signifies). Eric noted a height approaching 15cm (6in) and alluded to online references suggesting a maximum height approaching 1m (3ft). That latter figure is higher than I've previously read for any member of this tallest family of mosses (~ 2/3 of that figure), but certainly plausible in ideal circumstances.
At the level of cells and tissues, Dawsonia is one of the most structurally complex of mosses. Some cells differentiate into analogues of the water and nutrient-conducting cells of vascular plants, while others become the thick-walled cells necessary to support the free-standing height. This combination, only present in a rudimentary way in some mosses (and absent in many), provides Dawsonia with the ability to internally transport water and nutrients. In most other mosses, the absence of this quality limits their height to under 10cm (4in).
Paradoxically, despite its tallest freestanding moss reputation, Dawsonia produces some of the smallest spores among mosses. Up to 65 million spores measuring 5-8 µm in diameter can be generated by a single sporangium, like the one shown in the upper part of this photo.
More photographs of Dawsonia longifolia (and there aren't many online) can be found in the University of Singapore's Interactive Malesian Moss Database.
Posted by Daniel Mosquin at 6:04 AM| Comments (2)
February 22, 2007
Unidentified Moss
Conduction of water in bryophytes (mosses, liverworts and hornworts) is broadly classified in three ways: ectohydric, mixohydric and endohydric.
Ectohydric bryophytes lack any form of specialized cells for internal conduction. Instead, water is conducted externally, typically through capillary action. Reliance upon external conduction, I'm certain, is correlated with height of these organisms – they tend to be the shortest of the bryophytes.
Today's photograph of an unidentified bryid moss is an example of a mixohydric bryophyte. While some water is conducted externally, these organisms have a measure of internal cell specialization, such as hydroids or stereids, that give them the ability to move water and nutrients within its tissues. It is not bona fide conducting tissue, i.e., it does not form an interconnected system throughout the entire body of the plant (including leaves or entire length of the stem), but it does represent a rudimentary way to transport water internally and decrease reliance on external moisture for growth and reproduction.
The third grouping, endohydric bryophytes, is represented by this BPotD on Polytrichum juniperinum. In these plants, an internal conducting system exists that is analogous to the conducting system of vascular plants. By no coincidence (as is mentioned in the Polytrichum link), this grouping contains the tallest of bryophytes reaching over a half metre in height.
In all three broad groupings, it is important to note that water uptake tends to be from atmospheric moisture (suggested in today's photo) absorbed via the leaf or stem cells as opposed to uptake in moisture from the substrate (compare with vascular plants, which often uptake moisture via roots in soil). For both ectohydric and mixohydric bryophytes in particular, this means that water is absorbed near the top of organism and passed downward to subtending tissues, the inverse of the way one typically thinks about water uptake in plants.
Photography resource link: For inspiration, the photomicrography of Hans Van Rafelghem.
Posted by Daniel Mosquin at 6:02 AM| Comments (13)
January 26, 2007
Rhytidiadelphus triquetrus
If I had to make a list of my favourite top ten common names for plants, this one would surely be among them. I'll quote from Schofield's “Some Common Mosses of British Columbia”: Commonly called the rough neck moss or shaggy moss because of the untidy leaves at the shoot tips. A whimsical name, electrified cat tail moss, has gained some popularity in British Columbia (emphasis added). The USDA Plants Database uses rough goose neck moss, as yet another alternative. I'll stick with electrified cat tail moss. Had E. E. Cummings Walt Whitman (see comments) been a bryologist, I'm sure he would have written, “I sing the moss electric.” for this particular species.
Rhytidiadelphus triquetrus is circumpolar for the northern hemisphere in its distribution, extending south into lower latitudes along mountain ranges (e.g., California and Arkansas). A broad range typically means a plant can grow in a variety of conditions, and it is no exception. Substrates for this moss species include well-drained sites in coniferous forests, on boulders and logs and, less frequently, tree trunks (source is again Schofield's book), though Mosses and Liverworts in Wales also mentions dunes and “certain types of broad-leaf woodland”.
Photography resource link: From Guy Tal's “The Essential Landscape” series: In the Name of All That is Good – On the Roles of the Artist, the Activist, and the Critic via Nature Photographers Online. Guy questions whether it is possible to be both artist and activist.
Posted by Daniel Mosquin at 12:00 AM| Comments (6)
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Botany Photo of the Day and all associated images are licensed under a Creative Commons License.
Botany Photo of the Day is a project of the UBC Botanical Garden and Centre for Plant Research, located in Vancouver, British Columbia Canada. UBC BGCPR is a department of the Faculty of Land and Food Systems within The University of British Columbia.