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Seed Leaf
A cotyledon (; ; ; , gen. (), ) is a significant part of the embryo within the seed of a plant, and is defined as "the embryonic leaf in seed-bearing plants, one or more of which are the first to appear from a germinating seed." The number of cotyledons present is one characteristic used by botanists to classify the flowering plants (angiosperms). Species with one cotyledon are called monocotyledonous ("monocots"). Plants with two embryonic leaves are termed dicotyledonous ("dicots"). In the case of dicot seedlings whose cotyledons are photosynthetic, the cotyledons are functionally similar to leaves. However, true leaves and cotyledons are developmentally distinct. Cotyledons are formed during embryogenesis, along with the root and shoot meristems, and are therefore present in the seed prior to germination. True leaves, however, are formed post-embryonically (i.e. after germination) from the shoot apical meristem, which is responsible for generating subsequent aerial port ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coleoptile
Coleoptile is the pointed protective sheath covering the emerging shoot in monocotyledons such as grasses in which few leaf primordia and shoot apex of monocot embryo remain enclosed. The coleoptile protects the first leaf as well as the growing stem in seedlings and eventually, allows the first leaf to emerge. Coleoptiles have two vascular bundles, one on either side. Unlike the flag leaves rolled up within, the pre-emergent coleoptile does not accumulate significant protochlorophyll or carotenoids, and so it is generally very pale. Some preemergent coleoptiles do, however, accumulate purple anthocyanin pigments. Coleoptiles consist of very similar cells that are all specialised to fast stretch growth. They do not divide, but increase in size as they accumulate more water. Coleoptiles also have water vessels (frequently two) along the axis to provide a water supply. When a coleoptile reaches the surface, it stops growing and the flag leaves penetrate its top, continuing to grow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypogeal Germination
Hypogeal germination (from Ancient Greek [] 'below ground', from [] 'below' and [] 'earth, ground') is a botanical term indicating that the germination of a plant takes place below the ground. An example of a plant with hypogeal germination is the pea (''Pisum sativum''). The opposite of hypogeal is epigeal (above-ground germination). Germination Hypogeal germination implies that the cotyledons stay below the ground. The epicotyl (part of the stem above the cotyledon) grows, while the hypocotyl (part of the stem below the cotyledon) remains the same in length. In this way, the epicotyl pushes the plumule above the ground. Normally, the cotyledon is fleshy, and contains many nutrients that are used for germination. Because the cotyledon stays below the ground, it is much less vulnerable to for example night-frost or grazing. The evolutionary strategy is that the plant produces a relatively low number of seeds, but each seed has a bigger chance of surviving. Plants tha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epigeal Germination
Epigeal germination (Ancient Greek [] 'above ground', from [] 'on' and [] 'earth, ground') is a Glossary of botanical terms, botanical term indicating that the germination of a plant takes place above the ground. An example of a plant with epigeal germination is the common bean (''Phaseolus vulgaris''). The opposite of epigeal is hypogeal (underground germination). , Epi: Above + Geo: Earth , + Epigeal germination Epigeal germination implies that the cotyledons are pushed above ground. The hypocotyl elongates while the epicotyl remains the same in length. In this way, the hypocotyl pushes the cotyledon upward. Normally, the cotyledon itself contains very little nutrients in plants that show this kind of germination. Instead, the first leaflets are already folded up inside it, and photosynthesis starts to take place in it rather quickly.Parolin, P., Ferreira, L.V., Junk, W.J. (2003"Germination characteristics and establishment of trees from central Amazonian flood plains"'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored in carbohydrate molecules, such as sugars and starches, which are synthesized from carbon dioxide and water – hence the name ''photosynthesis'', from the Greek ''phōs'' (), "light", and ''synthesis'' (), "putting together". Most plants, algae, and cyanobacteria perform photosynthesis; such organisms are called photoautotrophs. Photosynthesis is largely responsible for producing and maintaining the oxygen content of the Earth's atmosphere, and supplies most of the energy necessary for life on Earth. Although photosynthesis is performed differently by different species, the process always begins when energy from light is absorbed by proteins called reaction centers that contain green chlorophyll (and other colored) pigments/chromoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Big-cone Pinyon
''Pinus maximartinezii'', called Martinez pinyon, big-cone pinyon or maxipiñon, is a pine in the pinyon pine group, native to west-central Mexico. Description It is a small tree, reaching tall and with a trunk diameter of up to . The bark is brown, thick and fissured at the base of the trunk. The leaves ('needles') are in fascicles of five, slender, long, and deep green to blue-green, with stomata confined to a bright white band on the inner surfaces. The cones are ovoid, massive, long and broad and up to weight when closed, green at first, ripening yellow-brown when 26–28 months old, with very thick, woody scales, typically 30–60 fertile scales. The scales are unusual for a pine in the soft pine group (''Pinus'' subgenus ''Strobus''); most pines in that group have flexible scales. The cones open to broad when mature. The seeds are long, with a thick shell, with a vestigial wing; the seedlings have 18–24 cotyledons, the highest number reported for any plant. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cupressus Sempervirens
''Cupressus sempervirens'', the Mediterranean cypress (also known as Italian cypress, Tuscan cypress, Persian cypress, or pencil pine), is a species of cypress native to the eastern Mediterranean region, in northeast Libya, southern Albania, southern and coastal Bulgaria, southern coastal Croatia and Slovenia, southern Montenegro, southern Bosnia and Herzegovina, southwestern North Macedonia, southern Greece, southern Turkey, Cyprus, northern Egypt, western Syria, Lebanon, Malta, Italy, southern France, Spain, Palestine, Israel, western Jordan, South Caucasus, and also a disjunct population in Iran. Description ''Cupressus sempervirens'' is a medium-sized coniferous evergreen tree to 35 m (115 ft) tall, with a conic crown with level branches and variably loosely hanging branchlets. It is very long-lived, with some trees reported to be over 1,000 years old. The foliage grows in dense sprays, dark green in colour. The leaves are scale-like, 2–5 mm long, and prod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeffrey Pine
''Pinus jeffreyi'', also known as Jeffrey pine, Jeffrey's pine, yellow pine and black pine, is a North American pine tree. It is mainly found in California, but also in the westernmost part of Nevada, southwestern Oregon, and northern Baja California.Safford, H.D. 2013. Natural Range of Variation (NRV) for yellow pine and mixed conifer forests in the bioregional assessment area, including the Sierra Nevada, southern Cascades, and Modoc and Inyo National Forests. Unpublished report. USDA Forest Service, Pacific Southwest Region, Vallejo, CA/ref> It is named in honor of its botanist documenter John Jeffrey (botanist), John Jeffrey. Description ''Pinus jeffreyi'' is a large coniferous evergreen tree, reaching tall, rarely up to tall, though smaller when growing at or near tree line. The leaves are needle-like, in bundles of three, stout, glaucous gray-green, long. The cones are long, dark purple when immature, ripening pale brown, with thinly woody scales bearing a short, sharp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monterey Pine
''Pinus radiata'' ( syn. ''Pinus insignis''), the Monterey pine, insignis pine or radiata pine, is a species of pine native to the Central Coast of California and Mexico ( Guadalupe Island and Cedros island). It is an evergreen conifer in the family Pinaceae. ''P. radiata'' is a versatile, fast-growing, medium-density softwood, suitable for a wide range of uses. Its silviculture reflects a century of research, observation and practice. It is often considered a model for growers of other plantation species. It is the most widely planted pine in the world, valued for rapid growth and desirable lumber and pulp qualities. Although ''P. radiata'' is extensively cultivated as a plantation timber in many temperate parts of the world, it faces serious threats in its natural range, due to the introduction of pine pitch canker ('' Fusarium circinatum''). Description ''P. radiata'' is a coniferous evergreen tree growing to tall in the wild, but up to in cultivation in optimum condi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypocotyl
The hypocotyl (short for "hypocotyledonous stem", meaning "below seed leaf") is the stem of a germinating seedling, found below the cotyledons (seed leaves) and above the radicle ( root). Eudicots As the plant embryo grows at germination, it sends out a shoot called a radicle that becomes the primary root, and then penetrates down into the soil. After emergence of the radicle, the hypocotyl emerges and lifts the growing tip (usually including the seed coat) above the ground, bearing the embryonic leaves (called cotyledons), and the plumule that gives rise to the first true leaves. The hypocotyl is the primary organ of extension of the young plant and develops into the stem. Monocots The early development of a monocot seedling like cereals and other grasses is somewhat different. A structure called the coleoptile, essentially a part of the ''cotyledon'', protects the young stem and plumule as growth pushes them up through the soil. A mesocotyl—that part of the young plant t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ginkgophyta
Ginkgoales are a gymnosperm order containing only one extant species: ''Ginkgo biloba'', the ginkgo tree. It is monotypic, (the only taxon) within the class Ginkgoopsida, which itself is monotypic within the division Ginkgophyta . The order includes five families, of which only Ginkgoaceae remains extant. History Ginkgophyta and Cycadophyta have a very ancient divergence dating to the early Carboniferous. The earliest representative of the group in the fossil record is probably '' Trichopitys'' from the Asselian (299-293 million years ago) of France. The earliest representatives of '' Ginkgo'', represented by reproductive organs similar to the living species, first appear in the Middle Jurassic, alongside other, related forms such as '' Yimaia'' and '' Karkenia'', which have differently arranged reproductive structures and seeds associated with ''Ginkgo''-like leaves. The diversity of Ginkgoales declined during the Late Cretaceous and Cenozoic, coincident with the rise of flo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones ( strobili), somewhat similar to conifer cones. Cycads have been reported to fix nitrogen in asso ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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