Lambdina fiscellaria, the mournful thorn or hemlock looper, is a moth of the family Geometridae. It is found in North America, from the Pacific to the Atlantic coast and from Canada south to Pennsylvania and California; the adult resembles the oak besma. Darker line across a second line across fore wings. Area between lines may be unshaded; the wingspan is about 35 mm. The moth flies from August to early October depending on the location; the larvae feed on hemlock, balsam fir, white spruce and other hardwoods. There are three recognised subspecies: Lambdina fiscellaria fiscellaria – eastern hemlock looper Lambdina fiscellaria lugubrosa – western hemlock looper Lambdina fiscellaria somniaria – western oak looper or Garry oak looper Lambdina fiscellaria, entomology.ualberta.ca Lambdina fiscellaria - hemlock looper - Hodges#6888, Bug Guide
In botany, shoots consist of stems including their appendages, the leaves and lateral buds, flowering stems and flower buds. The new growth from seed germination that grows upward is a shoot. In the spring, perennial plant shoots are the new growth that grows from the ground in herbaceous plants or the new stem or flower growth that grows on woody plants. In everyday speech, shoots are synonymous with stems. Stems, which are an integral component of shoots, provide an axis for buds and leaves. Young shoots are eaten by animals because the fibres in the new growth have not yet completed secondary cell wall development, making the young shoots softer and easier to chew and digest; as shoots grow and age, the cells develop secondary cell walls that have a tough structure. Some plants produce toxins that make their shoots less palatable. Many woody plants have long shoots. In some angiosperms, the short shoots called spur shoots or fruit spurs, produce the majority of flowers and fruit. A similar pattern occurs in some conifers and in Ginkgo, although the "short shoots" of some genera such as Picea are so small that they can be mistaken for part of the leaf that they have produced.
A related phenomenon is seasonal heterophylly, which involves visibly different leaves from spring growth and lammas growth. Whereas spring growth comes from buds formed the previous season, includes flowers, lammas growth involves long shoots. Bud Heteroblasty, abrupt change in the growth pattern of some plants as they mature Lateral shoot Sterigma, the "woody peg" below the leaf of some conifers Thorn, true thorns, as distinct from spines or prickles, are short shoots
The Pinophyta known as Coniferophyta or Coniferae, or as conifers, are a division of vascular land plants containing a single extant class, Pinopsida. They are gymnosperms, cone-bearing seed plants. All extant conifers are perennial woody plants with secondary growth; the great majority are trees. Examples include cedars, Douglas firs, firs, kauri, pines, redwoods and yews; as of 1998, the division Pinophyta was estimated to contain eight families, 68 genera, 629 living species. Although the total number of species is small, conifers are ecologically important, they are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, but in similar cool climates in mountains further south. Boreal conifers have many wintertime adaptations; the narrow conical shape of northern conifers, their downward-drooping limbs, help them shed snow. Many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the immense conifer forests of the world represent the largest terrestrial carbon sink.
Conifers are of great economic value for softwood paper production. The earliest conifers in the fossil record date to the late Carboniferous period arising from Cordaites, a genus of seed-bearing Gondwanan plants with cone-like fertile structures. Pinophytes and Ginkgophytes all developed at this time. An important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen and the seed, which allows the embryo to be transported and developed elsewhere. Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, were the dominant land plants of the Mesozoic, they were overtaken by the flowering plants, which first appeared in the Cretaceous, became dominant in the Cenozoic era. They were the main food of herbivorous dinosaurs, their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era. Conifer is a Latin word, a compound of conus and ferre, meaning "the one that bears cone".
The division name Pinophyta conforms to the rules of the International Code of Nomenclature for algae and plants, which state that the names of higher taxa in plants are either formed from the name of an included family, in this case Pinaceae, or are descriptive. A descriptive name in widespread use for the conifers is Coniferae. According to the ICN, it is possible to use a name formed by replacing the termination -aceae in the name of an included family, in this case preferably Pinaceae, by the appropriate termination, in the case of this division ‑ophyta. Alternatively, "descriptive botanical names" may be used at any rank above family. Both are allowed; this means that if conifers are considered a division, they may be called Coniferae. As a class they may be called Coniferae; as an order they may be called Coniferae or Coniferales. Conifers are the largest and economically most important component group of the gymnosperms, but they comprise only one of the four groups; the division Pinophyta consists of just one class, which includes both living and fossil taxa.
Subdivision of the living conifers into two or more orders has been proposed from time to time. The most seen in the past was a split into two orders and Pinales, but recent research into DNA sequences suggests that this interpretation leaves the Pinales without Taxales as paraphyletic, the latter order is no longer considered distinct. A more accurate subdivision would be to split the class into three orders, Pinales containing only Pinaceae, Araucariales containing Araucariaceae and Podocarpaceae, Cupressales containing the remaining families, but there has not been any significant support for such a split, with the majority of opinion preferring retention of all the families within a single order Pinales, despite their antiquity and diverse morphology; the conifers are now accepted as comprising seven families, with a total of 65–70 genera and 600–630 species. The seven most distinct families are linked in the box above right and phylogenetic diagram left. In other interpretations, the Cephalotaxaceae may be better included within the Taxaceae, some authors additionally recognize Phyllocladaceae as distinct from Podocarpaceae.
The family Taxodiaceae is here included in family Cupressaceae, but was recognized in the past and can still be found in many field guides. A new classification and linear sequence based on molecular data can be found in an article by Christenhusz et al; the conifers are an ancient group, with a fossil record extending back about 300 million years to the Paleozoic in the late Carboniferous period. Other classes and orders, now long extinct occur as fossils from the late Paleozoic and Mesozoic eras. Fossil conifers included many diverse forms, the most distinct from modern conifers being some herbaceous conifers with no woody stems. Major fossil orders of conifers or conifer-like plants include the Cordaitales, Vojnovskyales and also the Czekanowskiales (possibly
In botany, a bud is an undeveloped or embryonic shoot and occurs in the axil of a leaf or at the tip of a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be specialized to develop flowers or short shoots, or may have the potential for general shoot development; the term bud is used in zoology, where it refers to an outgrowth from the body which can develop into a new individual. The buds of many woody plants in temperate or cold climates, are protected by a covering of modified leaves called scales which enclose the more delicate parts of the bud. Many bud scales are covered by a gummy substance; when the bud develops, the scales may enlarge somewhat but just drop off, leaving a series of horizontally-elongated scars on the surface of the growing stem. By means of these scars one can determine the age of any young branch, since each year's growth ends in the formation of a bud, the formation of which produces an additional group of bud scale scars.
Continued growth of the branch causes these scars to be obliterated after a few years so that the total age of older branches cannot be determined by this means. In many plants scales do not form over the bud, the bud is called a naked bud; the minute underdeveloped leaves in such buds are excessively hairy. Naked buds are found in some shrubs, like some species of the Sumac and Viburnums and in herbaceous plants. In many of the latter, buds are more reduced consisting of undifferentiated masses of cells in the axils of leaves. A terminal bud occurs on the end of a stem and lateral buds are found on the side. A head of cabbage is an exceptionally large terminal bud, while Brussels sprouts are large lateral buds. Since buds are formed in the axils of leaves, their distribution on the stem is the same as that of leaves. There are alternate and whorled buds, as well as the terminal bud at the tip of the stem. In many plants buds appear in unexpected places: these are known as adventitious buds, it is possible to find a bud in a remarkable series of gradations of bud scales.
In the buckeye, for example, one may see a complete gradation from the small brown outer scale through larger scales which on unfolding become somewhat green to the inner scales of the bud, which are remarkably leaf-like. Such a series suggests that the scales of the bud are in truth leaves, modified to protect the more delicate parts of the plant during unfavorable periods. Buds are useful in the identification of plants for woody plants in winter when leaves have fallen. Buds may be classified and described according to different criteria: location, status and function. Botanists use the following terms: for location: terminal, when located at the tip of a stem; the term is usable as a synonym of resting, but is better employed for buds waiting undeveloped for years, for example epicormic buds. Buds The term bud is used by analogy within zoology as well, where it refers to an outgrowth from the body which develops into a new individual, it is a form of asexual reproduction limited to animals or plants of simple structure.
In this process a portion of the wall of the parent cell pushes out. The protuberance thus formed enlarges while at this time the nucleus of the parent cell divides. One of the resulting nuclei passes into the bud, the bud is cut off from its parent cell and the process is repeated; the daughter cell will begin to bud before it becomes separated from the parent, so that whole colonies of adhering cells may be formed. Cross walls cut off the bud from the original cell
Vesicle (biology and chemistry)
In cell biology, a vesicle is a large structure within a cell, or extracellular, consisting of liquid enclosed by a lipid bilayer. Vesicles form during the processes of secretion and transport of materials within the plasma membrane. Alternatively, they may be prepared artificially. If there is only one phospholipid bilayer, they are called unilamellar liposome vesicles; the membrane enclosing the vesicle is a lamellar phase, similar to that of the plasma membrane and vesicles can fuse with the plasma membrane to release their contents outside the cell. Vesicles can fuse with other organelles within the cell. Vesicles perform a variety of functions; because it is separated from the cytosol, the inside of the vesicle can be made to be different from the cytosolic environment. For this reason, vesicles are a basic tool used by the cell for organizing cellular substances. Vesicles are involved in metabolism, buoyancy control, temporary storage of food and enzymes, they can act as chemical reaction chambers.
The 2013 Nobel Prize in Physiology or Medicine was shared by James Rothman, Randy Schekman and Thomas Südhof for their roles in elucidating the makeup and function of cell vesicles in yeasts and in humans, including information on each vesicle's parts and how they are assembled. Vesicle dysfunction is thought to contribute to Alzheimer's disease, some hard-to-treat cases of epilepsy, some cancers and immunological disorders and certain neurovascular conditions. Vacuoles are cellular organelles which contain water. Plant cells have a large central vacuole in the center of the cell, used for osmotic control and nutrient storage. Contractile vacuoles are found in certain protists those in Phylum Ciliophora; these vacuoles take water from the cytoplasm and excrete it from the cell to avoid bursting due to osmotic pressure. Lysosomes are involved in cellular digestion. Food can be taken from outside the cell into food vacuoles by a process called endocytosis; these food vacuoles fuse with lysosomes which break down the components so that they can be used in the cell.
This form of cellular eating is called phagocytosis. Lysosomes are used to destroy defective or damaged organelles in a process called autophagy, they fuse with the membrane of the damaged organelle. Transport vesicles can move molecules between locations inside the cell, e.g. proteins from the rough endoplasmic reticulum to the Golgi apparatus. Membrane-bound and secreted proteins are made on ribosomes found in the rough endoplasmic reticulum. Most of these proteins mature in the Golgi apparatus before going to their final destination which may be to lysosomes, peroxisomes, or outside of the cell; these proteins travel within the cell inside of transport vesicles. Secretory vesicles contain materials. Cells have many reasons to excrete materials. One reason is to dispose of wastes. Another reason is tied to the function of the cell. Within a larger organism, some cells are specialized to produce certain chemicals; these chemicals are released when needed. Synaptic vesicles are located at presynaptic terminals in neurons and store neurotransmitters.
When a signal comes down an axon, the synaptic vesicles fuse with the cell membrane releasing the neurotransmitter so that it can be detected by receptor molecules on the next nerve cell. In animals endocrine tissues release hormones into the bloodstream; these hormones are stored within secretory vesicles. A good example is the endocrine tissue found in the islets of Langerhans in the pancreas; this tissue contains many cell types. Secretory vesicles hold the enzymes that are used to make the cell walls of plants, fungi and Archaea cells as well as the extracellular matrix of animal cells. Bacteria, Archaea and parasites release membrane vesicles containing varied but specialized toxic compounds and biochemical signal molecules, which are transported to target cells to initiate processes in favour of the microbe, which include invasion of host cells and killing of competing microbes in the same niche. Extracellular vesicles are produced by all domains of life including complex eukaryotes, both Gram-negative and Gram-positive bacteria and fungi.
Exosomes: membraneous vesicles of endocytic origin enriched in CD63 and CD81. Microvesicle, that are shed directly from the plasma membrane. Membrane particles, or large membranous vesicles CD133+, CD63− Apoptotic blebs or blebbing vesicles: released by dying cells; these are separated by density by differential centrifugation. Ectosomes were named in 2008. In humans, endogenous extracellular vesicles play a role in coagulation, intercellular signaling and waste management, they are implicated in the pathophysiological processes involved in multiple diseases, including cancer. Extracellular vesicles have raised interest as a potential source of biomarker discovery because of their role in intercellular communication, release into accessible body fluids and the resemblance of their molecular content to that of the releasing cells; the extracellular vesicles of stem cells known as the secretome of stem cells, are being researched and applied for therapeutic purposes, predominantly degenerative, auto-immune and/or inflammatory diseases.
Snow refers to forms of ice crystals that precipitate from the atmosphere and undergo changes on the Earth's surface. It pertains to frozen crystalline water throughout its life cycle, starting when, under suitable conditions, the ice crystals form in the atmosphere, increase to millimeter size and accumulate on surfaces metamorphose in place, melt, slide or sublimate away. Snowstorms develop by feeding on sources of atmospheric moisture and cold air. Snowflakes nucleate around particles in the atmosphere by attracting supercooled water droplets, which freeze in hexagonal-shaped crystals. Snowflakes take on a variety of shapes, basic among these are platelets, needles and rime; as snow accumulates into a snowpack, it may blow into drifts. Over time, accumulated snow metamorphoses, by sintering and freeze-thaw. Where the climate is cold enough for year-to-year accumulation, a glacier may form. Otherwise, snow melts seasonally, causing runoff into streams and rivers and recharging groundwater. Major snow-prone areas include the polar regions, the upper half of the Northern Hemisphere and mountainous regions worldwide with sufficient moisture and cold temperatures.
In the Southern Hemisphere, snow is confined to mountainous areas, apart from Antarctica. Snow affects such human activities as transportation: creating the need for keeping roadways and windows clear. Snow affects ecosystems, as well, by providing an insulating layer during winter under which plants and animals are able to survive the cold. Snow develops in clouds; the physics of snow crystal development in clouds results from a complex set of variables that include moisture content and temperatures. The resulting shapes of the falling and fallen crystals can be classified into a number of basic shapes and combinations, thereof; some plate-like and stellar-shaped snowflakes can form under clear sky with a cold temperature inversion present. Snow clouds occur in the context of larger weather systems, the most important of, the low pressure area, which incorporate warm and cold fronts as part of their circulation. Two additional and locally productive sources of snow are lake-effect storms and elevation effects in mountains.
Mid-latitude cyclones are low pressure areas which are capable of producing anything from cloudiness and mild snow storms to heavy blizzards. During a hemisphere's fall and spring, the atmosphere over continents can be cold enough through the depth of the troposphere to cause snowfall. In the Northern Hemisphere, the northern side of the low pressure area produces the most snow. For the southern mid-latitudes, the side of a cyclone that produces the most snow is the southern side. A cold front, the leading edge of a cooler mass of air, can produce frontal snowsqualls—an intense frontal convective line, when temperature is near freezing at the surface; the strong convection that develops has enough moisture to produce whiteout conditions at places which line passes over as the wind causes intense blowing snow. This type of snowsquall lasts less than 30 minutes at any point along its path but the motion of the line can cover large distances. Frontal squalls may form a short distance ahead of the surface cold front or behind the cold front where there may be a deepening low pressure system or a series of trough lines which act similar to a traditional cold frontal passage.
In situations where squalls develop post-frontally it is not unusual to have two or three linear squall bands pass in rapid succession only separated by 25 miles with each passing the same point in 30 minutes apart. In cases where there is a large amount of vertical growth and mixing the squall may develop embedded cumulonimbus clouds resulting in lightning and thunder, dubbed thundersnow. A warm front can produce snow for a period, as warm, moist air overrides below-freezing air and creates precipitation at the boundary. Snow transitions to rain in the warm sector behind the front. Lake-effect snow is produced during cooler atmospheric conditions when a cold air mass moves across long expanses of warmer lake water, warming the lower layer of air which picks up water vapor from the lake, rises up through the colder air above, freezes and is deposited on the leeward shores; the same effect occurs over bodies of salt water, when it is termed ocean-effect or bay-effect snow. The effect is enhanced when the moving air mass is uplifted by the orographic influence of higher elevations on the downwind shores.
This uplifting can produce narrow but intense bands of precipitation, which deposit at a rate of many inches of snow each hour resulting in a large amount of total snowfall. The areas affected by lake-effect snow are called snowbelts; these include areas east of the Great Lakes, the west coasts of northern Japan, the Kamchatka Peninsula in Russia, areas near the Great Salt Lake, Black Sea, Caspian Sea, Baltic Sea, parts of the northern Atlantic Ocean. Orographic or relief snowfall is caused when masses of air pushed by wind are forced up the side of elevated land formations, such as large mountains; the lifting of air up the side of a mountain or range results in adiabatic cooling, condensation and precipitation. Moisture is removed by orographic lift, leaving drier, warmer air on the leeward side; the resulting enhanced productivity of snow fall and the decrease in temperature with elevation means that snow depth
A seed is an embryonic plant enclosed in a protective outer covering. The formation of the seed is part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm plants. Seeds are the product of the ripened ovule, after fertilization by pollen and some growth within the mother plant; the embryo is developed from the seed coat from the integuments of the ovule. Seeds have been an important development in the reproduction and success of gymnosperm and angiosperm plants, relative to more primitive plants such as ferns and liverworts, which do not have seeds and use water-dependent means to propagate themselves. Seed plants now dominate biological niches on land, from forests to grasslands both in hot and cold climates; the term "seed" has a general meaning that antedates the above – anything that can be sown, e.g. "seed" potatoes, "seeds" of corn or sunflower "seeds". In the case of sunflower and corn "seeds", what is sown is the seed enclosed in a shell or husk, whereas the potato is a tuber.
Many structures referred to as "seeds" are dry fruits. Plants producing berries are called baccate. Sunflower seeds are sometimes sold commercially while still enclosed within the hard wall of the fruit, which must be split open to reach the seed. Different groups of plants have other modifications, the so-called stone fruits have a hardened fruit layer fused to and surrounding the actual seed. Nuts are the one-seeded, hard-shelled fruit of some plants with an indehiscent seed, such as an acorn or hazelnut. Seeds are produced in several related groups of plants, their manner of production distinguishes the angiosperms from the gymnosperms. Angiosperm seeds are produced in a hard or fleshy structure called a fruit that encloses the seeds for protection in order to secure healthy growth; some fruits have layers of both fleshy material. In gymnosperms, no special structure develops to enclose the seeds, which begin their development "naked" on the bracts of cones. However, the seeds do become covered by the cone scales.
Seed production in natural plant populations varies from year to year in response to weather variables and diseases, internal cycles within the plants themselves. Over a 20-year period, for example, forests composed of loblolly pine and shortleaf pine produced from 0 to nearly 5 million sound pine seeds per hectare. Over this period, there were six bumper, five poor, nine good seed crops, when evaluated for production of adequate seedlings for natural forest reproduction. Angiosperm seeds consist of three genetically distinct constituents: the embryo formed from the zygote, the endosperm, triploid, the seed coat from tissue derived from the maternal tissue of the ovule. In angiosperms, the process of seed development begins with double fertilization, which involves the fusion of two male gametes with the egg cell and the central cell to form the primary endosperm and the zygote. Right after fertilization, the zygote is inactive, but the primary endosperm divides to form the endosperm tissue.
This tissue becomes the food the young plant will consume until the roots have developed after germination. After fertilization the ovules develop into the seeds; the ovule consists of a number of components: The funicle or seed stalk which attaches the ovule to the placenta and hence ovary or fruit wall, at the pericarp. The nucellus, the remnant of the megasporangium and main region of the ovule where the megagametophyte develops; the micropyle, a small pore or opening in the apex of the integument of the ovule where the pollen tube enters during the process of fertilization. The chalaza, the base of the ovule opposite the micropyle, where integument and nucellus are joined together; the shape of the ovules as they develop affects the final shape of the seeds. Plants produce ovules of four shapes: the most common shape is called anatropous, with a curved shape. Orthotropous ovules are straight with all the parts of the ovule lined up in a long row producing an uncurved seed. Campylotropous ovules have a curved megagametophyte giving the seed a tight "C" shape.
The last ovule shape is called amphitropous, where the ovule is inverted and turned back 90 degrees on its stalk. In the majority of flowering plants, the zygote's first division is transversely oriented in regards to the long axis, this establishes the polarity of the embryo; the upper or chalazal pole becomes the main area of growth of the embryo, while the lower or micropylar pole produces the stalk-like suspensor that attaches to the micropyle. The suspensor absorbs and manufactures nutrients from the endosperm that are used during the embryo's growth; the main components of the embryo are: The cotyledons, the seed leaves, attached to the embryonic axis. There may be two; the cotyledons are the source of nutrients in the non-endospermic dicotyledons, in which case they replace the endosperm, are thick and leathery. In endospermic seeds the cotyledons are papery. Dicotyledons have the point of attachment opposite one another on the axis; the epicotyl, the embryonic axis above the point of attachment of the cotyledon.
The plumule, the tip of the epicotyl, has a feathery appearance due to the presence of young leaf primordia at the apex, will become the shoot upon germination. The hypocotyl, the embryonic axis below the point of attachment of the cotyledon, connecting the epicotyl and the radicle, being the stem-root transition zone; the radicle, the basal tip of the hy