In botany Botany, plant science, phytology, or plant biology is a branch of biology and is the scientific study of plant life and development. Botany covers a wide range of scientific disciplines that study plants, algae, and fungi including: structure, growth, reproduction, metabolism, development, diseases, chemical properties, and evolutionary, a leaf is an above-ground plant organ In biology and anatomy, an organ is a collection of tissues joined in structural unit to serve a common function specialized for photosynthesis Photosynthesis is a process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of Bacteria, but not in Archaea. Photosynthetic organisms are called photoautotrophs, since they can create their own food. In plants, algae and cyanobacteria. For this purpose, a leaf is typically flat (laminar) and thin. There is continued debate about whether the flatness of leaves evolved Natural selection is the process by which heritable traits that make it more likely for an organism to survive and successfully reproduce become more common in a population over successive generations. It is a key mechanism of evolution to expose the chloroplasts Chloroplasts are organelles found in plant cells and other eukaryotic organisms that conduct photosynthesis. Chloroplasts capture light energy to conserve free energy in the form of ATP and reduce NADP to NADPH through a complex set of processes called photosynthesis to more light Light is electromagnetic radiation, particularly radiation of a wavelength that is visible to the human eye . In physics, the term light sometimes refers to electromagnetic radiation of any wavelength, whether visible or not or to increase the absorption of carbon dioxide Carbon dioxide is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state. CO2 is a trace gas being only 0.038% of the atmosphere. In either case, the adaption was made at the expense of water loss. In the Devonian period The Devonian is a geologic period and system of the Paleozoic era spanning from 416 to 359.2 million years ago . It is named after Devon, England, where rocks from this period were first studied, when carbon dioxide concentration was at several times its present value, plants did not have leaves or flat stems. Many bryophytes Bryophytes are all embryophytes that are non-vascular: they have tissues and enclosed reproductive systems, but they lack vascular tissue that circulates liquids. They neither have flowers nor produce seeds, reproducing via spores. The term bryophyte comes from Greek βρύον - bryon, "tree-moss, oyster-green" + φυτόν - fyton & have flat, photosynthetic organs, but these are not true leaves. Neither are the microphylls The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based. The traditional definition of microphylls and megaphylls will be employed in this article for simplicity; of lycophytes The Division Lycopodiophyta is a tracheophyte subdivision of the Kingdom Plantae. It is the oldest extant (living) vascular plant division at around 410 million years old,:99 and includes some of the most "primitive" extant species. These species reproduce by shedding spores and have macroscopic alternation of generations, although some. The leaves of ferns, gymnosperms The gymnosperms are a group of seed-bearing plants that includes conifers, cycads, Ginkgo and Gnetales. The term "gymnosperm" comes from the Greek word gymnospermos , meaning "naked seeds", after the unenclosed condition of their seeds (called ovules in their unfertilized state). Their naked condition stands in contrast to the, and angiosperms The flowering plants or angiosperms are the most diverse group of land plants. The flowering plants and the gymnosperms are the only extant groups of seed plants. The flowering plants are distinguished from other seed plants by a series of apomorphies, or derived characteristics are variously referred to as macrophyll The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based. The traditional definition of microphylls and megaphylls will be employed in this article for simplicity;, megaphylls The terminology of fossil plants is in places a little confusing. In the discipline's 200+ year history, certain concepts have become entrenched, even though improved understanding has threatened the foundations upon which they are based. The traditional definition of microphylls and megaphylls will be employed in this article for simplicity;, or euphylls.
Leaves are also the sites in most plants where transpiration Transpiration is a process similar to evaporation. It is the loss of water from parts of plants, especially leaves but also stems, flowers and roots. Leaf surfaces are dotted with openings called stomata, and in most plants they are more numerous on the undersides of the foliage. The stoma are bordered by guard cells that open and close the pore and guttation Guttation is the appearance of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses. Guttation is not to be confused with dew, which condenses from the atmosphere onto the plant surface take place. Leaves can store food Food is any substance, usually composed of carbohydrates, fats, proteins and water, that can be eaten or drunk by an animal, including humans, for nutrition or pleasure. Items considered food may be sourced from plants, animals or other categories such as fungus or fermented products like alcohol. Although many human cultures sought food items and water Water is a ubiquitous chemical substance that is composed of hydrogen and oxygen and is vital for all known forms of life, and are modified in some plants for other purposes. The comparable structures of ferns A fern is any one of a group of about 12,000 species of plants . Unlike mosses they have xylem and phloem . They have stems, leaves, and roots like other vascular plants. Ferns do not have either seeds or flowers (they reproduce via spores) are correctly referred to as fronds The term frond is used to refer to a large, divided leaf. In both common usage and botanical nomenclature, the leaves of ferns are referred to as fronds and some botanists restrict the term to this group. Other botanists allow the term frond to also apply to the large leaves of cycads and palms . Furthermore, leaves are prominent in the human Humans commonly refers to the species Homo sapiens , the only extant member of the Homo genus of bipedal primates in Hominidae, the great ape family. However, in some cases the term is used to refer to any member of the genus Homo diet In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. Although humans are omnivores, each culture holds some food preferences and some food taboos. Individual dietary choices may be more or less healthful. Proper as leaf vegetables Leaf vegetables, also called potherbs, green vegetables, greens, or leafy greens, are plant leaves eaten as a vegetable, sometimes accompanied by tender petioles and shoots. Although they come from a very wide variety of plants, most share a great deal with other leaf vegetables in nutrition and cooking methods.
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Still, a bit less than half of Wagoner's western sky view is still tainted by the Maple Leaf City's light dome. I can see the Milky Way from my yard but ...
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Wed, 24 Feb 2010 16:58:28 GM
Maple . Leaf. Foods Inc. posted a return to fourth-quarter profitability Wednesday, continuing its recovery.
