Of what adaptive value is a greater thickness along the midrib of moss/ferns?
601953
It allows teachers to ask school kids questions that make them think rather than just regurgitating from a book.\n\nOf course when lazy or dumb kids cheat by using a website it becomes sort of pointless.
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The two parts that you have mentioned belong to same leaf but not necessarily identical in function and face different environmental factors.\n\n1)The upper surface of a typical leaf-:\n\nThis part receives direct sunlight and does more photosynthesis so it has more chloroplasts and it is darker green as compared to the other side.\nIt has water proof coating of wax or cuticle and less hair hence it is more smooth and shining.\n\n2)Lower surface  of a typical leaf-: \n\n This part is away from the direct sun light and has less chloroplast so pale green in color. It is more concerned with gaseous exchange. It has less waterproofing hence not so shiny.It has more hairy outgrowth to maintain humidity around stomata, so rough in texture.
1030030
There isn't a "species", because Aloe vera is itself the species you are asking about. However, I have seen some varieties of it with hardly any spikes along the leaf edges. In part, I think this may happen when it is growing rapidly in length. I don't know specifically how to encourage this kind of leaves, but looking for an individual with this type of leaves might work for you? Also, look for a representative with FAT leaves, and they won't seem as spiky.
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Mosses are usually less than 2" high.
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Bryophyte are soil formers in primary and secondary succession.
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THE ADAPTIVE FEATURES OF HALOPHYTES:-\n\n1) High osmotic concentration of the cell sap: - The halophytes have cell sap concentration at much higher level than that of the surrounding sea water, so that they can absorb water from the sea. This is the single most important adaptive feature with out which they would not live.\nIn fact, this feature is present in all the marine plants such as sea weeds and the kelps. It is as much as 12 times higher than the one found in ordinary land plants.\n2) Presence of thick epidermis: - The leaf epidermis is thickly cuticularised to prevent excessive transpiration. The stomata are less frequent or sunken on the upper epidermis and located mostly along the lower epidermis, which is not much exposed to direct harsh sunlight in this, they are similar to desert plants or xerophytes.\n3) Presence of salt excreting glands: - On the leaf surface, they have special glands through which they get rid of the excess sea salt that accumulates in the body.\n4) Vivipary germination: - this is yet another feature unique to these plants, in which the seed begins to germinate while the fruit is still attached to the parental tree. The radicle that comes out is massive and tapering. When it the seed finally gets detached from the parent it sinks vertically down like a dart due to this massive radicle and the radicle gets embedded in the mud/sand. There the further development of a new tree continues.\nThus, the possibility of the seed being washed away with the tides in to deep sea and lost is entirely eliminated.\nIt is because of this habit, the halophytes (Mangroves) develop thick impenetrable forests wherever they grow.\n The nature is clever than the man thinks.
543152
Well, you probably know grasses do not have a "calyx" or "corola;" they do have bracts and glumes.  Do you need more specific info.? I will check back.
430128
Non-vascular plants do not have vascular systems to carry water, nutrients, ant the products of photosynthesis throughout the plant. Non-vascular plants include mosses, ferns, hornworts, and liverworts. The mosses, hornworts, and liverworts all transport water by osmosis so they cannot grow very large. This is why they must live so close to water. Ferns have a primitive forrunner of a vascular system, but it is not really a real vascular system because they do not have true roots, and also lack xylem, which is a type of cell that carries water and nutrients up the plant, and phloem, which are cells that can carry water, nutrients, and the products of photosythesis throughout the plant. If you have any more questions, I'll check back here for updates if this was helpfull at all.
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I'm going to assume you are talking about plants. It depends. More transpiration means more water flows through plants, so of course more nutrients will enter the plant tissue. However, the amount that is actually absorbed for use by the plant is controlled by the plant cells.... excess minerals are usually stored.
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(if you need this for homework, please rewrite it in a coherent way!)\nThe plants that live in xeric (=dry) environments are called xerophytes and have many adaptations that help reduce water loss. Basically these include mechanisms for 1) reducing body surface (because evaporation/transpiration is directly proportional to body surface) and 2) reinforcing their "skin" to make it less permeable.\n\nAdaptations tending to 1) include:\n- Small and thick or absent leaves, may be transformed into spines; they photosinthesize with their stems (such as cacti)\n- Short, stumpy shape; rounded stems.\n\nAdaptations tending to 2) include:\n- Leaves with multilayered epidermis and a thick waxy cover (waterproof)\n- Leaves may be covered with hairs.\n- Small stomata, situated in recessed crypts\n- Some have the stomata open only during the nighttime (CAM metabolism)
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cactus r xerophytic plants which have the ability to retain water in it.so cactus retains more water and there leaves get modified into spines due to which there is less loss of water from the plant in the atmosphere due to which they can withstand on the extreme condition of water that is where less water is present,and as in desert there is less water so can withstand over there succesfully than to those plants whose leaves are broad and have no cuticle layer.
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How ironic; spent half the night figuring this out too... here's some of my notes\n\n•2n or not 2n: The story of the sporophyte\n\n1.gametophyte definition – “In plants, the haploid (n), gamete producing generation, which alternates with the diploid (2n) sporophyte.”\n2.sporophyte definition – “the spore producing, diploid(2n)phase in the life cycle of a plant having alternating generations.”\n3.Gametophytes and sporophytes don’t always look the same.\n4.the dominance of each differs in the phyla.\n5.With increasing complexity: the gametophyte becomes LESS dominant while the sporophyte becomes MORE dominant.\n6.In mosses, the Sporophyte is parasitic upon gametophyte. In other words, what we largely see is a photosynthetic and free living gametophyte supporting a sporophyte. \n7.However, evolution has favoured the opposite, on the whole sporophytes are large and the gametophyte small.  For example, in conifers, the gametophyte is hidden within an acorn and the sporophyte is depending on other organisms to use the acorn as food and release the gametophyte. Moreover, angiosperms have reduced gametophytes to ovules and pollen. \n\nHope this helps?
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I will split your question in to two parts viz. 1) Photosynthesis and 2) Stomata; so that you can easily understand it.\n 1) PHOTOSYNTHESIS-: for this function entire middle portion of a leaf contributes, it is called MESOPHYLL in botanical language.(Meso = middle or in between; Phyll = refers to leaf). It is located in between the upper and the lower skin or the epidermis of a leaf (Plural epidermes).\n In most of the leaves the MESOPHYLL is again distinguished it to Upper PALISDE tissue and the Lower SPONGY LAYER.\n Both of them are full of chloroplast and do the function of photosynthesis; but there is a difference.\n The palisade cells are located near the upper epidermis,they are elongated,test tube like in appearence and are placed at right angle to the upper epidermis like upright test tubes.( try to see the meaning of palisade in a good dictionary, it is interesting.). These palisade cells are very closely packed with very little space in between and each of them is literally packed with chloroplasts. That is why a leaf appears greener on its upper surface.Thus, they are ideally located to receive maximum sun light and do maximum photosynthesis.\n\nThe Spongy layer , on the other hand , is located near the lower epidermis of a leaf. The cells are spherical or potato shaped and with lots of intercellular spaces between them. Each cell of this layer contains (comparitively) less or far less number of chloroplasts than the palisade of the same leaf.That is why the same leaf appears pale green on its lower surface.\n This Spongy layer does the function of photosynthesis no doubt ; but it is less in quantity than that of Palisade of the same leaf. This is because it is located rather away from the light source and its main function is to help the leaf in gaseous exchange, that is why there are so many intercellular spaces.( here Photosynthesis is over)... \n\n2) STOMATA (singular stoma) -: These breathing pores are neither IN the palisade layer nor IN the spongy layer. They are a PART of the the two epidermes( upper and lower ).\n If one compares the quantity and the distribution of these stomata of one and the same leaf then they are more on the lower epidermis to help the spongy tissue in gaseous exchange during photosynthesis/respiration.\n On the upper epidermis they are far less in number to reduce or prevent exessive water loss due to transpiration.\nIn many desert plants they are either totally absent from the upper epidermis or located in sunken pits for the same reason.\nI hope you got what you sought. Bye.
518387
a) is correct.\nIn vascular plants, secondary growth or, perhaps more accurately, secondary thickening is the result of the activity of the vascular cambium. The latter is a meristem that divides off cells: the cells on the inside of the meristem (the adaxial side) will become secondary xylem, while the cells on the outside (the abaxial side) will become the secondary phloem. This growth increases the girth of the plant, rather than its length, hence the phrase "secondary thickening". As long as the vascular cambium continues to produce new cells, the plant will continue to grow more stout. If this is kept up over many years, this process produces wood.Because this growth ruptures the epidermis of the stem, woody plants also may have a cork cambium that develops among the phloem. The cork cambium gives rise to thickened cork cells to protect the surface of the plant and reduce water loss.
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Tree rings.  trees grow faster in warm climates, so the thickness of the rings provides information about climate.\n\nIce cores. Snow is deposited in layers.  Thick layer - more precipiitation. \n\nPollen stratigraphy.  Plants generally grow in defined climatic regions.  If pollen from a type of plantt is found where such pollen is no longer found we can deduce information about the climate at the time that the pollen was produced.
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ferns   ferns   ferns..
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The presence or absence of vascular tissues is used to clarify plants.\n\nIt is because of that vascular tissue that plants are capable of growing to different sizes and heights.\n\nFor example - mosses and lichens have little to no vascular tissue. This is why they are relatively small, and located only near damp places like swamps, bogs, or near the sea coast. Trees, by comparison, not only have cascular tissues, but they have 2 kinds of it! One type of xylem and phloem (the vascular tissues) become the parts that make up the bark, while another type of each, make up the wood of the tree. Basically any timber you buy from the lumber yard, is nothing but primary xylem and phloem.