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Parastichy
Parastichy, in phyllotaxy, is the spiral pattern of particular plant organs on some plants, such as areoles on cacti stems, florets in sunflower heads and scales in pine cones. These spirals involve the insertion of a single primordium. See also * Embryology * * Gerrit van Iterson * * Phyllotaxis In botany, phyllotaxis () or phyllotaxy is the arrangement of leaf, leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature. Leaf arrangement The basic leaf#Arrangement on the stem, arrangements of leaves ... References External links Smith College Spiral Lattices & Parastichy Interactive Parastichies Explorer Plant morphology {{plant-morphology-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeonium Tabuliforme
''Aeonium tabuliforme'', the flat-topped aeonium or saucer plant, is a species of succulent plant in the family Crassulaceae, native and endemic to Tenerife in the Canary Islands. It is low-growing, typically reaching about 5 cm high but up to 45 cm in diameter. It grows on moist, north-facing cliffs and ledges at low altitude. A mass of fleshy, hairy, bright green leaves in flat rosettes is produced on short unbranched stems, often on vertical surfaces. This species is short-lived and dies after flowering. Plants often take 3–4 years to flower, at which point they produce a tall (40–60 cm) raceme of yellow flowers. The Latin specific epithet ''tabuliforme'' means "flat" (literally "table shaped"). This plant, which may be either biennial or perennial, is grown under glass in temperate regions. It has gained the Royal Horticultural Society's Award of Garden Merit. It requires excellent drainage, and leaf color is best in full sun. It is relatively disease-free ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllotaxy
In botany, phyllotaxis () or phyllotaxy is the arrangement of leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature. Leaf arrangement The basic arrangements of leaves on a stem are opposite and alternate (also known as spiral). Leaves may also be whorled if several leaves arise, or appear to arise, from the same level (at the same node) on a stem. With an opposite leaf arrangement, two leaves arise from the stem at the same level (at the same node), on opposite sides of the stem. An opposite leaf pair can be thought of as a whorl of two leaves. With an alternate (spiral) pattern, each leaf arises at a different point (node) on the stem. Distichous phyllotaxis, also called "two-ranked leaf arrangement" is a special case of either opposite or alternate leaf arrangement where the leaves on a stem are arranged in two vertical columns on opposite sides of the stem. Examples include various bulbous plants such as '' Boophone''. It a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Areole
In botany, areoles are small light- to dark-colored bumps on cactus, cacti out of which grow clusters of Thorns, spines, and prickles, spines. Areoles are important diagnostic features of cactus, cacti, and identify them as a family distinct from other succulent plants. Gordon Douglas Rowley, Gordon Rowley - What is an Areole The spines are not easily detachable, but on certain cacti, members of the subfamily Opuntioideae, smaller, detachable bristles, glochids, also grow out of the areoles and afford additional protection. Areoles represent highly specialized branches on cacti. They evolved as abortive branch buds while their spines evolved as vestigial leaves. In branched cacti, such as Opuntioidiae and the saguaro, new branches grow from areoles, because that is where the buds are. The development of the areole seems to have been an important element in the adaptation of cacti to niches in desert ecology. Some of the Opuntioideae have spines, as well as glochids, on their a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cacti
A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, from the Ancient Greek word (''káktos''), a name originally used by Theophrastus for a spiny plant whose identity is now not certain. Cacti occur in a wide range of shapes and sizes. They are native to the Americas, ranging from Patagonia in the south to parts of western Canada in the north, with the exception of '' Rhipsalis baccifera'', which is also found in Africa and Sri Lanka. Cacti are adapted to live in very dry environments, including the Atacama Desert, one of the driest places on Earth. Because of this, cacti show many adaptations to conserve water. For example, almost all cacti are succulents, meaning they have thickened, fleshy parts adapted to store water. Unlike many other succulents, the stem is the only part of most cacti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pine Cone
A conifer cone, or in formal botanical usage a strobilus, : strobili, is a seed-bearing organ on gymnosperm plants, especially in conifers and cycads. They are usually woody and variously conic, cylindrical, ovoid, to globular, and have scales and bracts arranged around a central axis, but can be fleshy and berry-like. The cone of Pinophyta (conifer clade) contains the reproductive structures. The woody cone is the female cone, which produces seeds. The male cone, which produces pollen, is usually ephemeral and much less conspicuous even at full maturity. The name "cone" derives from Greek ''konos'' (pine cone), which also gave name to the geometric cone. The individual plates of a cone are known as ''scales''. In conifers where the cone develops over more than one year (such as pines), the first year's growth of a seed scale on the cone, showing up as a protuberance at the end of the two-year-old scale, is called an ''umbo'', while the second year's growth is called the '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Primordium
A primordium (; : primordia; synonym: anlage), in embryology, is an Organ (anatomy), organ or tissue in its earliest recognizable stage of development. Cell (biology), Cells of the primordium are called primordial cells. A primordium is the simplest set of cells capable of triggering growth of the would-be organ and the initial foundation from which an organ is able to grow. In flowering plants, a floral primordium gives rise to a flower. Although it is a frequently used term in plant biology, the word is used in describing the biology of all multicellular organisms (for example: a tooth primordium in animals, a leaf primordium in plants or a sporocarp (fungi), sporophore primordium in fungi.) Primordium development in plants Plants produce both leaf and flower primordia cells at the shoot apical meristem (SAM). Primordium development in plants is critical to the proper positioning and development of plant organs and cells. The process of primordium development is intricately r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryology
Embryology (from Ancient Greek, Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logy, -logia'') is the branch of animal biology that studies the Prenatal development (biology), prenatal development of gametes (sex cells), fertilization, and development of embryos and fetuses. Additionally, embryology encompasses the study of congenital disorders that occur before birth, known as teratology. Early embryology was proposed by Marcello Malpighi, and known as preformationism, the theory that organisms develop from pre-existing miniature versions of themselves. Aristotle proposed the theory that is now accepted, Epigenesis (biology), epigenesis. Epigenesis (biology), Epigenesis is the idea that organisms develop from seed or egg in a sequence of steps. Modern embryology developed from the work of Karl Ernst von Baer, though accurate observations had been made in Italy by anatomists such as Aldrovandi and Leonardo da Vinci in the Renaissance. Comparative ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerrit Van Iterson
''This page was created from the Dutch Wikipedia with the aid of automatic translation'' Gerrit van Iterson Jr (Roermond, 19 August 1878 – Wassenaar Wassenaar (; population: in ) is a municipality and town located in the province of South Holland, on the western coast of the Netherlands. An affluent suburb of The Hague, Wassenaar lies north of that city on the N44/A44 highway near the Nort ..., 4 January 1972) was a Dutch botanist and professor who developed a mathematical approach to plant growth (phyllotaxis). Biography Gerrit van Iterson studied in the Department of Chemical Engineering at the Delft University of Technology, Polytechnic in Delft from 1897 to 1901. He studied chemistry under H. Behrens and microbiology under Martinus Willem Beijerinck. He got a PhD in 1907 with a thesis on phyllotaxis, where he fielded a mathematical theory for leaf growth (''Mathematical und Studien über microscopic anatomical Blattstellungen, etc.''). He also created a diagram that ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllotaxis
In botany, phyllotaxis () or phyllotaxy is the arrangement of leaf, leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature. Leaf arrangement The basic leaf#Arrangement on the stem, arrangements of leaves on a stem are opposite and alternate (also known as spiral). Leaves may also be Whorl (botany), whorled if several leaves arise, or appear to arise, from the same level (at the same Node (botany), node) on a stem. With an opposite leaf arrangement, two leaves arise from the stem at the same level (at the same Node (botany), node), on opposite sides of the stem. An opposite leaf pair can be thought of as a whorl of two leaves. With an alternate (spiral) pattern, each leaf arises at a different point (node) on the stem. Distichous phyllotaxis, also called "two-ranked leaf arrangement" is a special case of either opposite or alternate leaf arrangement where the leaves on a stem are arranged in two vertical columns on opposite sides of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
