Moss

__** Moss **__
 * By: Niharika Kareddy **





Moss is classified as a Bryophyta, a type of nonvascular plant, meaning that it does not have any tracheids (a characteristic of vascular plants) which are fluid conducting cells, so the plants cannot retain water or deliver it to other parts of the pant body. . They are distinguishable due to their filamentous (long and thin) stage and the fact that their sporophyte, the multicellular diploid plant called “spore plant” grows from the tip. These plants will rarely grow too tall and tend to grow in dense mats and lack true leaves, stems, and roots that characterize vascular plants apart from nonvascular plants such as moss.
 * 1. Classification/Diagnostic characteristics **
 * Kingdom: Plantae ||
 * Division: Bryophyta ||
 * Subdivision: Musci ||
 * Class: Bryopsida ||
 * Subclass: Bryidae ||
 * Order: Fissidentales ||
 * Family: Fissidenticeae ||
 * Genus: Fissidens Hedw. ||

Moss can be used as a decorative landscaping piece because usually most nonvascular land plants grow on bare rock, on dead or fallen trees, and buildings. This prompts a mutualistic relationship with fungi where the two cooperatively facilitate the absorption of water and minerals especially in soils and this is used by humans to promote growth in gardens and create nutrient rich soil. Decaying moss of the genus Sphagnum is a major ingredient of peat, which has many commercial uses, as fuel, a soil additive, or for smoking malt to brew Scotch whiskey. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Sphagnum moss has seen use as a make-shift bandage in WWI, since they are absorbent and mildly antibacterial. Moss has seen various uses by native tribes. Native Americans used the moss to make diapers and napkins, and this practice is still in use today in Canada. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">In addition, researchers at ETH Zurich have discovered that moss are able to manufacture human proteins when injected with human genes. This may prove to be a cost-effective way for manufacturing crucial proteins such as insulin for commercial use.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">2. Relationship to humans **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">There are about 15,000 different species of mosses and they are usually found in damp, cool ground where water is readily available. This growth in thick mats result in quick transport of water through capillary action and mineral distribution through diffusion. But, some moss gametophytes are so big that they can't transport enough water solely through diffusion. These gametophytes and sporophytes contain a kind of cell called hydroid which dies and leaves a water channel for water to travel through. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Moss can be found in the tropics, boreal forests, temperate woodlands, and the tundra. In fact, moss can make up 50-90% of a tundra's biomass.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">3. Habitat and niche **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">The use of camouflage because of its green dense mat nature helps it avoid predators in the forest. Also its abundance and mutualistic existence helps to keep it alive and helps it thrive in almost any terrestrial place.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">4. Predator avoidance **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Nonvascular plants lack an efficient vascular system that allows for easy water and mineral transport to far away places of the plant body. Because moss lacks proper leaves and stems, it depends on its growth form to move nutrients and water by capillary action. They have these leaf-like structures that catch and hold water for use. Also, their small size acts to their advantage where the minerals can be distributed through diffusion. Layers of maternal tissue preserve and protect their embryos and a cuticle which only slightly helps to stop water loss. Also, moss is better off than liverworts because it has stomata which help with water retention and gas exchange.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">5. Nutrient acquisition **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">The life cycle of moss is just like other plants and is characterized by the concept of alteration of generation. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">A diploid generation (containing 2 complete chromosomes from both of the parents), called the sporophyte, follows a haploid generation (a single set of unpaired chromosomes), called the gametophyte, which is in turn followed by another sporophyte generation. The green, "leafy" mosses on the banks of streams are all haploid gametophytes. The diploid generation of the plant arises after a male and female gametophyte mate and fuse their haploid gametes. The resulting diploid zygote grows into the sporophyte—the long stalked structure bearing a sporangium. This sporophyte is a new generation in the life cycle, yet the new organism can never leave the gametophyte, because it depends on the gametophyte for its nutrients. When the sporangium breaks open and releases its haploid spores, a new generation of gametophytes can germinate. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">media type="custom" key="24454864"
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">6. Reproduction and life cycle **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Nonvascular plants do not have leaves, stems, and roots, although they have analogous structures to each. Water can move through the mats by capillary action, leaf like structures catch and hold water. They grow to be on average a few centimeters tall to allow water and minerals to reach all parts. To attach to rocks, moss have small root-like structures called rhizoids that function as adherents and water absorbing mechanisms. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Mosses break down exposed substrata, releasing nutrients for the use of more complex plants that succeed them. They aid in soil-erosion control by providing surface cover and absorbing water, and they are important in the nutrient and water economy of some vegetation types
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">7. Growth and development **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Integument, a protective surface covering, can be seen in moss when the layers of maternal tissue protect the embryos from drying out. Mosses also have a cuticle, a waxy coating that slows water loss, but it can be very thin and thus ineffective. To minimize water loss, the aerial parts of vascular land plants are covered with a hydrophobic layer called a cuticle. The cuticle typically consists of two major components: cutin and waxes. In contrast to vascular plants, research reports indicate that some primitive nonvascular plants, such as mosses, lack a cuticle. That is why even though mosses can have a cuticle, they are ineffective because cuticles are not usually good for nonvascular plants who need to preserve water as much as possible.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">8. Integument **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Moss is a stationary plant and doesn't travel from site to site. But movement can be observed during reproduction. When germinating, moss is encapsulated by peristome which regulate the release of spores dependent on environmental conditions. If the environment is wet, the spores cannot be released; if the environment is dry, the spores are released from their capsule and may travel along with wind currents. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">9. Movement **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Moss can sense change in the environment through stomata and its use of photosynthesis, essential to keeping the plant alive.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">10. Sensing the environment **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">The use of stomata helps moss perform gas exchange. Stomata works through pores to perform efficient gas exchange because it allows the organism to get new CO2 and excrete O2 like other plants that do photosynthesis. They consist of guard cells which surround the stoma. Food is then made from the carbon dioxide and water through photosynthesis. Stomata open in the presence of sunlight and carbon dioxide diffuses into the leaf. As this happens, water vapor exits the leaf through transpiration. Many times, plants must decide whether they should continue to take in carbon dioxide if it means losing water vapor.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">11. Gas exchange **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Waste removal happens through active transport through ion concentrations and how to regulate concentrations as regular plants regulate waste. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Fortunately for humans, for mosses, like other plants, oxygen is in fact a waste product, released by plants through the stomata (see above). <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Mosses do not accumulate as many wastes as the typical animal since they do not ingest other organisms, so the few wastes they do pick up can simply be stored. For example, calcium and other minerals in excess can be stored in central vacuoles.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">12. Waste removal **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Water regulation: <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Hydroids are a certain type of cell within the gametophytes and sporophytes which dies and leaves a tiny tunnel where water can travel. Hydroids act like the tracheid, the water conducting cell of vascular plants, but do not have lignin or the cell wall structure. Stomata also play a role in water loss. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">In a study done, the moss and a desert shrub both photosynthesize over different temperatures and they exist in different temperatures so this is a product of acclimation which is where the plant goes through small physiological changes which help to maintain homeostasis and help the plant survive.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">13. Environmental physiology (temperature, water and salt regulation) **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Moss lacks a highly complex network of tubules, including a xylem (water transport) and a phloem (nutrient transport) as in vascular plants, or tracheophytes(tube plants). For this reason, moss is limited in height, which is why it grows short but covers a wide area. It usually grows in damp moist environments in order to allow diffusion of water and other nutrients into its cells. However, they contain a few water conducting strands in their central stems, later leading to the evolution of more developed transport systems in other plants.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">14. Internal circulation **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Hormones help to regulate growth and development of the plant itself like any other plant. Cytokinin, a plant hormone that promotes cell division, has been found to create budding cells in moss, which aids in rapid growth if needed.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">15. Chemical control (i.e. endocrine system) **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">1.) What is the concept of alteration of generation? How does this allow the life cycle to continue for moss? <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">2.) How do nonvascular plants similar to moss grow and develop? How is this different than growth and development of vascular plants? <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">3.) How does water regulation happen without the use of tracheids, the fluid conducting cells? <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">4.) What are some key characteristics of plants that are missing in moss that affect the way its internal circulation happens? <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">5.) What is the part of the moss that helps to perform gas exchange and allows for photosynthesis to occur?
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Review Questions: **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">[] (1) <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://fresnoweedman.blogspot.com/2013/05/dont-let-moss-grow-under-your-feet.html <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://www.youtube.com/watch?v=jcWYAnmm-QE <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://scienceline.ucsb.edu/getkey.php?key=975 <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://www.eoearth.org/view/article/156262/ <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">[] <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">[] <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://science.jrank.org/pages/4458/Moss-Habitat-ecology.html http://www.ethlife.ethz.ch/archive_articles/090505_mensch_moos_mas/index_EN <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">[] <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://sky.scnu.edu.cn/life/class/ecology/chapter/Chapter4.htm <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://www.cliffsnotes.com/sciences/biology/biology/plants-diversity-and-reproduction/nonvascular-plants-defined <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://plants.usda.gov/java/ClassificationServlet?source=display&classid=FISSI2 <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://www.britannica.com/EBchecked/topic/393741/moss <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://digitalcommons.ric.edu/ebook_gallery/21/
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Sources: **