question: Why does moss grow on the north side of a tree in the northern hemisphere? How does it know? Why does it matter?
comment: Moss likes cool and damp areas. The north side of a tree will receive the least amount of sunlight compared to the others, meaning it will be slightly cooler and likely more damp due to less evaporation, creating a better enviroment for the moss to grow. Moss will actually grow on any side of a tree it can, it's just that the North Side of the tree will be the easiest for it to take hold.
passages: It is generally believed that in northern latitudes, the north side of trees and rocks will generally have more luxuriant moss growth on average than other sides. This is assumed to be because the sun on the south side creates a dry environment. South of the equator the reverse would be true. However, naturalists feel that mosses grow on the damper side of trees and rocks. In some cases, such as sunny climates in temperate northern latitudes, this will be the shaded north side of the tree or rock. On steep slopes it may be the uphill side. For mosses that grow on tree branches, this is generally the upper side of the branch on horizontally growing sections or near the crotch. In cool damp cloudy climates, all sides of tree trunks and rocks may be equally damp enough for mosses. And different species of mosses have different moisture and sun requirements so will grow on different sections of the same tree or rock.
   Choice of substrate varies by species as well. Moss species can be classed as growing on: rocks, exposed mineral soil, disturbed soils, acid soil, calcareous soil, cliff seeps and waterfall spray areas, streamsides, shaded humusy soil, downed logs, burnt stumps, tree trunk bases, upper tree trunks, and tree branches or in bogs. Moss species growing on or under trees are often specific about the species of trees they grow on, such as preferring conifers to broadleaf trees, oaks to alders, or vice versa. While mosses often grow on trees as epiphytes, they are never parasitic on the tree.
   In rural UK, "Fontinalis antipyretica" was traditionally used to extinguish fires as it could be found in substantial quantities in slow-moving rivers and the moss retained large volumes of water which helped extinguish the flames. This historical use is reflected in its specific Latin/Greek name, the approximate meaning of which is "against fire".
  
  In Finland, peat mosses have been used to make bread during famines. In Mexico, Moss is used as a Christmas decoration.
  
  "Physcomitrella patens" is increasingly used in biotechnology. Prominent examples are the identification of moss genes
   In one of the simplest examples, it is assumed that the hyphal tips try to keep a 45 degree orientation with relation to the Earth’s gravity vector field, and also generate some kind of scalar field that the growing tips try to avoid. This combination of parameters leads to development of hollow conical structures, similar to the fruit bodies of some primitive fungi.
   Robinson has pioneered the use of isotope analysis and other chemical makers for understanding how Antarctic mosses function and how climate change is affecting Antarctic plants. Through her research using of radiocarbon bomb spike she has been able to date Antarctic mosses – providing long-term growth records that demonstrate these are “old growth mosses”.
   Section::::Ecology.:Moss-cyanobacteria relationship.
  
  In boreal forests, some species of moss play an important role in providing nitrogen for the ecosystem due to their relationship with nitrogen-fixing cyanobacteria. Cyanobacteria colonizes moss and receives shelter in return for providing fixed nitrogen. Moss releases the fixed nitrogen, along with other nutrients, into the soil "upon disturbances like drying-rewetting and fire events," making it available throughout the ecosystem.
  
  Section::::Cultivation.
   The characterization of these behaviors might suggest that crown shyness is simply the result of mutual shading based on well-understood shade avoidance responses. Malaysian scholar Francis S.P. Ng, who studied "Dryobalanops aromatica" in 1977 suggested that the growing tips were sensitive to light levels and stopped growing when nearing the adjacent foliage due to the induced shade.
   Mosses share fundamental genetic and physiological processes with vascular plants, although the two lineages diverged early in land-plant evolution. A comparative study between modern representatives of the two lines may give insight into the evolution of mechanisms that contribute to the complexity of modern plants. In this context, "P. patens" is used as a model organism.
   They were often but not always the object of the Wild Hunt. According to folklore, in order to escape the hunt they enter the trees that woodsmen have marked with a cross that will be chopped down.
  
  "Des Knaben Wunderhorn" records "folk-songs [that] make the huntsman in the wood start a dark-brown maid, and hail her: 'whither away, "wild beast"?', but his mother did not take to the bride."
  
  The moss people are similar to hamadryads. Their lives are "attached to the trees; if any one causes by friction the inner bark to loosen a Wood-woman dies."
   Dollman's tree mouse is nocturnal and arboreal. Nowak (1999) suggests that the naked tip of its tail might be prehensile.
  
  Section::::Relationships.
   Donald R. Currey was a graduate student at the University of North Carolina at Chapel Hill studying the climate dynamics of the Little Ice Age using dendrochronology techniques. In 1963 he became aware of the bristlecone populations in the Snake Range in general, and on Wheeler Peak in particular. Based on the trees' size, growth rate and growth forms, he became convinced that some were very old, cored some of them, and found trees exceeding 3,000 years in age, but Currey was not able to obtain a continuous series of overlapping cores from WPN-114.
   The modelling process starts from the proposition that each hypha in the fungal mycelium generates a certain abstract field that (like known physical fields) decrease with increasing distance. Both scalar and vector fields are included in the models. The field(s) and its (their) gradient(s) are used to inform the algorithm that calculates the likelihood of branching, the angle of branching and the growth direction of each hyphal tip in the simulated mycelium. The growth vector is being informed of its surroundings so, effectively, the virtual hyphal tip is sensing the neighbouring mycelium. This is why we call it the Neighbour-Sensing model.
   While cytokinin action in vascular plants is described as pleiotropic, this class of plant hormones specifically induces the transition from apical growth to growth via a three-faced apical cell in moss protonema. This
  
  bud induction can be pinpointed to differentiation of a specific single cell, and thus is a very specific effect of cytokinin.
   Moss dwarf males (also known as nannandry or phyllodioicy) originate from wind-dispersed male spores that settle and germinate on the female shoot where their growth is restricted to a few millimeters. In some species, dwarfness is genetically determined, in that all male spores become dwarf. More often, however, it is environmentally determined in that male spores that land on a female become dwarf, while those that land elsewhere develop into large, female-sized males. In the latter case, dwarf males that are transplanted from females to another substrate develop into large shoots, suggesting that the females emit a substance which inhibits the growth of germinating males and possibly also quickens their onset of sexual maturation. The nature of such a substance is unknown, but the phytohormone auxin may be involved
   Section::::Defensive communication.:Communication.
  
  Many studies report that mycorrhizal networks facilitate the coordination of defenses between connected plants using volatile organic compounds and other plant defensive enzymes acting as infochemicals.
   Moss such as Lanky Moss is a crucial component in primary successional success. After a major disturbance such as a fire or glacial advancement, moss and lichen are initial species in the regrowth of vegetation. Since other feather mosses unlike Rhytidiadelphus loreaus are capable of nitrogen fixation they are able to facilitate growth of other species because they can introduce a crucial nutrient into the growing forest.
  
  Section::::Importance.:Primary Succession.
   When ectomycorrhizal fungi receiver end of the plant has limited sunlight availability, there was an increase in carbon transfer, indicating a source-sink gradient of carbon among plants and shade surface area regulates carbon transfer.
  
  Section::::Importance at the forest community level.:Water transfer.
   A legend amongst the Nootka peoples of the Hesquiaht First Nation tells of the origins of the Nootka cypress. In the legend, a raven encounters three young women drying salmon on the beach. He asks the women if they are afraid of being alone, if they are afraid of bears, wolves, and other animals. Each women responded "no". But when asked about owls, the women were indeed afraid of owls. Hearing this, the trickster raven hid in the forests, and made the calls of an owl. The terrified women ran up the mountains, but turned into Nootka cypress trees when they were out of breath. According to the Nootka, this is why Nootka cypress grows on the sides of mountains, and also why the bark is silky like a woman's hair, the young trunk is smooth like a woman's body.
   One possible explanation for plant thermoregulation is to provide protection against cold temperature. For example, the skunk cabbage is not frost-resistant, yet it begins to grow and flower when there is still snow on the ground. Another theory is that thermogenicity helps attract pollinators, which is borne out by observations that heat production is accompanied by the arrival of beetles or flies.
  
  Section::::Behavioral temperature regulation.
   It has recently been found that microarthropods, such as springtails and mites, can effect moss fertilization and that this process is mediated by moss-emitted scents. Male and female fire moss, for example emit different and complex volatile organic scents. Female plants emit more compounds than male plants. Springtails were found to choose female plants preferentially, and one study found that springtails enhance moss fertilization, suggesting a scent-mediated relationship analogous to the plant-pollinator relationship found in many seed plants. The stinkmoss species "Splachnum sphaericum" develops insect pollination further by attracting flies to its sporangia with a strong smell of carrion, and providing a strong visual cue in the form of red-coloured swollen collars beneath each spore capsule. Flies attracted to the moss carry its spores to fresh herbivore dung, which is the favoured habitat of the species of this genus.
   These transfer mechanisms can facilitate movement of nutrients via mycorrhizal networks and result in behavioral modifications in connected plants, as indicated by morphological or physiological changes, due to the infochemicals being transmitted. One study reported a three-fold increase in photosynthesis in a paper birch transferring carbon to a Douglas fir, indicating a physiological change in the tree which produced the signal. Photosynthesis was also shown to be increased in Douglas fir seedlings by the transport of carbon, nitrogen and water from an older tree connected by a mycorrhizal network. Furthermore, nutrient transfer from older to younger trees on a network can dramatically increase growth rates of the younger receivers. Physiological changes due to environmental stress have also initiated nutrient transfer by causing the movement of carbon from the roots of the stressed plant to the roots of a conspecific plant over a mycorrhizal network. Thus, nutrients transferred through mychorrhizal networks act as signals and cues to change the behavior of the connected plants.
   Another form of plant communication occurs through their complex root networks. Through roots, plants can share many different resources including nitrogen, fungi, nutrients, microbes, and carbon. This transfer of below ground carbon is examined in Philip et al. 2011. The goals of this paper were to test if carbon transfer was bi-directional, if one species had a net gain in Carbon, and if more Carbon was transferred through the soil pathway or common mycorrhizal network (CMN). CMNs occur when fungal mycelia link roots of plants together (Philip et al. 2011). To test this, the researchers followed seedlings of paper birch and Douglas-fir in a greenhouse for 8 months, where hyphal linkages that crossed their roots were either severed or left intact. The experiment measured amounts of CO2 in both seedlings. It was discovered that there was indeed a bi-directional sharing of CO2 between the two trees, with the Douglas-fir receiving a slight net gain in CO2. Also, the Carbon was transferred through both soil and the CMN pathways, as transfer occurred when the CMN linkages were interrupted, but much more transfer occurred when the CMN’s were left unbroken. This experiment showed that through fungal mycelia linkage of the roots of two plants, plants are able to communicate with one another and transfer nutrients as well as other resources through below ground root networks (Philip et al. 2011). Further studies go on to argue that this underground “tree talk” is crucial in the adaptation of forest ecosystems. Plant genotypes have shown that mycorrhizal fungal traits are heritable and play a role in plant behavior. These relationships with fungal networks can be mutualistic, commensal, or even parasitic. It has been shown that plants can rapidly change behavior such as root growth, shoot growth, photosynthetic rate, and defense mechanisms in response to mycorrhizal colonization (Gorzelak et al. 2015). Through root systems and common mycorrhizal networks, plants are able to communicate with one another below ground and alter behaviors or even share nutrients depending on different environmental cues.
   Section::::Mating.:Female/male interactions.:Mate choice.
  
  In terms of locating mates, males cannot find females unless they release pheromones, so the females control how frequently they mate. When females do send out their pheromones, the first male to reach a female will mate with her.
  
  Section::::Mating.:Female/male interactions.:Number of mates.
   Some plants may have subaerial roots, either totally (epiphytic plants such as some orchids) or more commonly only partly so. The oil palm tree can grow roots into accumulations of decaying leaves on the soil surface; these roots are said to be subaerial. Epiphyte plants growing above ground that do not feed from their tree support (for example through their haustorium or feeding part having dug into the tree, such as Mistletoe) have subaerial roots (for example some Ficus species).
   Kinship can act as another transfer mechanism. More carbon has been found to be exchanged between the roots of more closely related Douglas firs sharing a network than more distantly related roots. Evidence is also mounting that micronutrients transferred via mycorrhizal networks can communicate relatedness between plants. Carbon transfer between Douglas fir seedlings led workers to hypothesize that micronutrient transfer via the network may have increased carbon transfer between related plants.
  
  Section::::Nutrient communication.:Communication.
  
presuppositions: Moss grows on the north side of trees. Moss only grows on the north side of a tree, in the northern hemisphere. 
corrections: Moss will grow on all sides of a tree, however the north side is the easiest side for moss to take hold. Moss can grow on any side of a tree, however the north side is the easiest side for it to take hold.
raw_presuppositions: Moss grows on the north side of trees. Moss only grows on the north side of a tree, in the northern hemisphere.  Moss only grows on the north side of a tree.
raw_corrections: Moss will grow on all sides of a tree, however the north side is the easiest side for moss to take hold. Moss can grow on any side of a tree, however the north side is the easiest side for it to take hold. Moss can grow on any side of a tree, however the north side is the easiest side for it to take hold.