"prior to cytokinesis, whereas in successive microsporogenesis cytokinesis follows. While there may be a continuum with intermediate forms, the type of microsporogenesis has systematic significance. The predominant form amongst the monocots is successive, but there are important exceptions. During microgametogenesis, the unicellular microspores undergo mitosis and develop into mature microgametophytes containing the gametes. In some flowering plants, germination of the pollen grain may begin even before it leaves the microsporangium, with the generative cell forming the two sperm cells. Except in the case of some submerged aquatic plants, the mature pollen grain has a double wall. The vegetative and generative"
"Stamen The stamen (plural ""stamina"" or ""stamens"") is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium. A stamen typically consists of a stalk called the filament and an anther which contains ""microsporangia"". Most commonly anthers are two-lobed and are attached to the filament either at the base or in the middle area of the anther. The sterile tissue between the lobes is called the connective. A pollen grain develops from a microspore in the microsporangium and contains the male gametophyte. The stamens in a flower are collectively called the androecium. The androecium can consist of"
"persists after flowering, but instead of withering, begins to grow until it forms a bladder-like enclosure around the fruit. This is an effective protection against some kinds of birds and insects, for example in ""Hibiscus trionum"" and the Cape gooseberry. Morphologically, both sepals and petals are modified leaves. The calyx (the sepals) and the corolla (the petals) are the outer sterile whorls of the flower, which together form what is known as the ""perianth"". The term ""tepal"" is usually applied when the parts of the perianth are difficult to distinguish, e.g. the petals and sepals share the same color, or"
"are also common. The hull of the mature bean is hard, water-resistant, and protects the cotyledon and hypocotyl (or ""germ"") from damage. If the seed coat is cracked, the seed will not germinate. The scar, visible on the seed coat, is called the hilum (colors include black, brown, buff, gray and yellow) and at one end of the hilum is the micropyle, or small opening in the seed coat which can allow the absorption of water for sprouting. Some seeds such as soybeans containing very high levels of protein can undergo desiccation, yet survive and revive after water absorption. A."
"serve to protect the sporophylls and to form an envelope attractive to pollinators. The individual members of these surrounding structures are known as sepals and petals (or tepals in flowers such as ""Magnolia"" where sepals and petals are not distinguishable from each other). The outer series (calyx of sepals) is usually green and leaf-like, and functions to protect the rest of the flower, especially the bud. The inner series (corolla of petals) is, in general, white or brightly colored, and is more delicate in structure. It functions to attract insect or bird pollinators. Attraction is effected by color, scent, and"
"the peridium remains closed until the spores are mature, and even then shows no special arrangement for dehiscence or opening, but has to decay before the spores are liberated. For most fungi, the peridium is ornamented with scales or spines. In species that become raised above ground during their development, generally known as the ""puffballs"", the peridium is usually differentiated into two or more layers, where the outer layer is usually resolved into warts or spines. In contrast, the inner layer remains continuous and smooth to preserve the spores. Sometimes, as in the case of ""Geaster"", the number of layers"
"character of the fronds, which are evergreen, persisting for 1-2 years, pinnate or pinnatifid (rarely simple entire), and from 10-80 cm or more long. The sori or groups of spore-cases (sporangia) are borne on the back of the frond; they are globose and naked, not covered with a membrane (indusium). Polypodies have some use in herbalism, but are today most important in horticulture where several species, hybrids, and their cultivars like ""Polypodium"" 'Green Wave' are commonly used as ornamental plants for shady locations. ""Polypodium"" have a bitter-sweet taste and are among the rather few ferns that are used in cooking;"
"Resting spore A resting spore is a resistant cell, used to survive adverse environmental conditions. Resting spore is a term commonly applied to both diatoms and fungi. A resting spore can be a spore created by fungi which is thickly encysted (has a thick cell wall) in order to survive through stressful times, such as drought. It protects the spore from biotic (microbial, fungal viral), as well as abiotic (wind, heat, xeric conditions) factors. It is found in ""Anabaena"". Resting spores of a particular fungus are known create the phenomenon known as late potato blight. They can lie dormant within"
"Sporopollenin Sporopollenin is one of the most chemically inert biological polymers. It is a major component of the tough outer (exine) walls of plant spores and pollen grains. It is chemically very stable and is usually well preserved in soils and sediments. The exine layer is often intricately sculptured in species-specific patterns, allowing material recovered from (for example) lake sediments to provide useful information to palynologists about plant and fungal populations in the past. Sporopollenin has found uses in the field of paleoclimatology as well. Sporopollenin is also found in the cell walls of several taxa of green alga, including"
"Arthur considered ""Uromyces claytoniae"" to be synonymous with ""P. mariae-wilsoniae"", but this conclusion was rejected in a later publication, and the putative synonymy is recognized by neither of the taxonomic databases Index Fungorum nor MycoBank. The epithet honors Mary L. Wilson, a Buffalo-area botanist who frequently collected specimens for Peck. The fungus is commonly known as the ""spring beauty rust"". The rust grows on all sides of the plant, producing scattered clusters of reddish-brown sori on the surface. The aecia (specialized reproductive structures) are cup-shaped and have a conspicuous peridium. The spores produced by the aecia (aeciospores) are hyaline (translucent),"
"The peridium can also refer to the outer ""nest"" of a bird's-nest fungus. Peridium The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of gasteroid fungi. Depending on the species, the peridium may vary from being paper-thin to thick and rubbery or even hard. Typically, peridia consist of one to three layers. If there is only a single layer, it is called a peridium. If two layers are present, the outer layer is called the exoperidium and the inner layer the endoperidium. If three layers are present, they"
"small, young plants), with the pinnae opposite on the stalk. Each pinna is 3–11 cm long, with a large upward-pointing pinnule at the base, and the other pinnules decreasing in size toward the pinna tip; the pinnules have bristly tips. Individual fronds live for 1.5-2.5 years and remain attached to the rhizome after withering. The round sori occupy two rows on either side of the midrib of each pinnule and are covered by a centrally-attached, umbrella-like indusium with fringed edges. They produce light yellow spores. The Latin specific epithet ""aculeatum"" means “bristly”. ""Polystichum aculeatum"" is grown as an ornamental plant"
"""Phycopeltis"" (an ulvophycean) and ""Chlorella"". Spores are dispersed by many different environmental factors, such as wind, water or animals. If the conditions are suitable the sporopollenin-impregnated walls of pollen grains and spores can persist in the fossil record for hundreds of millions of years, since sporopollenin is resistant to chemical degradation by organic and inorganic chemicals. The chemical composition of sporopollenin is not exactly known, due to its unusual chemical stability and resistance to degradation by enzymes and strong chemical reagents. Analyses have revealed a mixture of biopolymers, containing mainly long chain fatty acids, phenylpropanoids, phenolics and traces of carotenoids."
"maturity, the peridium opens up and remains as a volva at the base of the receptaculum. The fertile portion of the fruiting body is often borne on the end of a wide, fleshy or spongy stalk (as in the Phallales), which may be cylindrical, star-shaped, or reticulate (forming a network). They may be brightly colored, sometimes with a lattice- or veil-like membrane enclosing and protecting the spores. The spore-containing substance, the gleba, is typically gelatinous, often foul-smelling, and deliquescent (becoming liquid from the absorption of water). The gleba is formed on the exterior face of the cap or the upper"
"dehulling is still often done by hand using a large mortar and pestle. These are usually made of wood, and operated by one or more people. The husk is biodegradable and may be composted. Husk Husk (or hull) in botany is the outer shell or coating of a seed. It often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed, fruit, or vegetable. It can also refer to the exuvia of bugs or small animals left behind after"
"the spores of various ""Calostoma"" species. The spore reticulations have purpose: they become entangled and interwoven with nurse cells and scaly hyphae, the net effect of which is to prevent the spores from being blown away simultaneously. When grown in humid conditions, such as might typically be found in a temperate deciduous forest, ""Calostoma"" species develop a thicker, more gelatinous exoperidium (the outermost peridial layer). As the stalk expands, the exoperidium becomes sloughed off, exposing the endoperidum and a raised peristome—the ridge of tissue around the opening suggestive of the common name, ""prettymouth"". The exoperidium may help to protect the"
"Peridium The peridium is the protective layer that encloses a mass of spores in fungi. This outer covering is a distinctive feature of gasteroid fungi. Depending on the species, the peridium may vary from being paper-thin to thick and rubbery or even hard. Typically, peridia consist of one to three layers. If there is only a single layer, it is called a peridium. If two layers are present, the outer layer is called the exoperidium and the inner layer the endoperidium. If three layers are present, they are the exoperidium, the mesoperidium and the endoperidium. In the simplest subterranean forms,"
"recycled back into the food web of the photic zone. Resting spore A resting spore is a resistant cell, used to survive adverse environmental conditions. Resting spore is a term commonly applied to both diatoms and fungi. A resting spore can be a spore created by fungi which is thickly encysted (has a thick cell wall) in order to survive through stressful times, such as drought. It protects the spore from biotic (microbial, fungal viral), as well as abiotic (wind, heat, xeric conditions) factors. It is found in ""Anabaena"". Resting spores of a particular fungus are known create the phenomenon"
"apart to reveal the seeds, which are 2–3 cm in length. The pollen carry on the outside a glycocalyx, which consists of densely packed cylindrical units measuring 20 to 150 nanometers. They are perpendicular to the plasma membrane. Below is the sporopollenin. The germinal openings (apertures) are more proximal than distal. At the distal end of each pollen grain, there is an unusual pit (pseudosulcus) that resembles a ""failed"" distal aperture. It is native to a narrow coastal strip, some 800 kilometres in extent, in the KwaZulu-Cape and Maputaland coastal forest mosaics of South Africa and southern Mozambique. The western"
"Husk Husk (or hull) in botany is the outer shell or coating of a seed. It often refers to the leafy outer covering of an ear of maize (corn) as it grows on the plant. Literally, a husk or hull includes the protective outer covering of a seed, fruit, or vegetable. It can also refer to the exuvia of bugs or small animals left behind after moulting. In cooking, hull can also refer to other waste parts of fruits and vegetables, notably the cap or sepal of a strawberry. The husk of a legume and some similar fruits is called"
"Pollen Pollen is a fine to coarse powdery substance comprising pollen grains which are male microgametophytes of seed plants, which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophytes during the process of their movement from the stamens to the pistil of flowering plants, or from the male cone to the female cone of coniferous plants. If pollen lands on a compatible pistil or female cone, it germinates, producing a pollen tube that transfers the sperm to the ovule containing the female gametophyte. Individual pollen grains are small enough to require"
"such a mark, and can be used as a distinguishing characteristic of a seed or spore. Hilum (biology) In botany, a hilum (pronounced ) is a scar or mark left on a seed coat by the former attachment to the ovary wall or to the funiculus (which in turn attaches to the ovary wall). On a bean seed, the hilum is called the ""eye"". For some species of fungus, the hilum is the microscopic indentation left on a spore when it separates from the sterigma of the basidium. A hilum can also be a nucleus of a starch grain; the"
"contains two microsporangia, also known as pollen sacs. The microsporangia produce the microspores, which for seed plants are known as pollen grains. If the pollen sacs are not adjacent, or if they open separately, then no thecae are formed. In Lauraceae, for example, the pollen sacs are spaced apart and open independently. The tissue between the locules and the cells is called the ""connective"" and the parenchyma. Both pollen sacs are separated by the stomium. When the anther is dehiscing, it opens at the stomium. The outer cells of the theca form the epidermis. Below the epidermis, the somatic cells"
"This could mean that the concentration and type of lignin units could provide additional resistance to fungal decay for plants protected by bark. Cork, sometimes confused with bark in colloquial speech, is the outermost layer of a woody stem, derived from the cork cambium. It serves as protection against damage from parasites, herbivorous animals and diseases, as well as dehydration and fire. Cork can contain antiseptics like tannins, that protect against fungal and bacterial attacks that would cause decay. In some plants, the bark is substantially thicker, providing further protection and giving the bark a characteristically distinctive structure with deep"
"Velamen Velamen is a spongy, multiple epidermis that covers the roots of some epiphytic or semi-epiphytic plants, such as orchid and ""Clivia"" species. The velamen of an orchid is the white or gray covering of aerial roots (when dry, and usually more green when wet as a result of the appearance of underlying photosynthetic structures). It is many cell layers thick and capable of absorbing atmospheric moisture and nutrients, but its main function may lie in protecting the underlying cells against damaging UV rays (Chomicki et al., 2015). Often, the roots of orchids are associated with symbiotic fungi or bacteria;"
"formed from an entire leaf whose development and form is greatly modified. These are hairy, short-stalked, bean-shaped structures (usually 3 to 8 mm in diameter) with a hardened outer covering. This outer covering is tough and resistant to drying out, allowing the spores inside to survive unfavorable conditions such as winter frost or summer desiccation. Despite this toughness, the sporocarps will open readily in water if conditions are favorable, and specimens have been successfully germinated after being stored for more than forty years. Each growing season, only one sporocarp develops per node along the rhizome near the base of the"
"have been conducted to better understand the life and infection cycle of ""C. carbonum. Cochliobolus carbonum"" survives as mycelium and resistant chlamydospores on maize debris in the field and on infected seed. Conidia serve as a primary source of inoculum dispersed by wind and rain-splash. Damp weather and moderate temperature greatly favor sporulation and produce additional inoculum for secondary spread. During both pathogenic and saprophytic phases of the lifecycle, this fungus enters and ramifies through intact leaves and obtains nutrients from the host cytoplasm and walls by degrading cell wall components through the production of a variety of extracellular enzymes."
"grain. The pollen grains are dispersed by the wind to the female, ovulate cone that is made up of many overlapping scales (sporophylls, and thus megasporophylls), each protecting two ovules, each of which consists of a megasporangium (the nucellus) wrapped in two layers of tissue, the integument and the cupule, that were derived from highly modified branches of ancestral gymnosperms. When a pollen grain lands close enough to the tip of an ovule, it is drawn in through the micropyle ( a pore in the integuments covering the tip of the ovule) often by means of a drop of liquid"
"in an extracellular secretion. The secretion prevents conidia from desiccating and protects them from unfavorable environmental conditions. Overwintering on corn residue serves as a vital source of primary inoculum for the leaf blight phase in the spring. The cycle will start all over again when susceptible corn seedlings emerge from the ground in the spring. Since C. graminicola is found to survive on corn residue, specifically on the soil surface; one of the most effective methods of control is a one-year minimum of crop rotation to reduce anthracnose leaf blight. A study in 2009 showed more severe symptoms of leaf"
"pollen of visiting insects or by various hairs, flaps, or sculpturings. The style and stigma of the flower are involved in most types of self incompatibility reactions. Self-incompatibility, if present, prevents fertilization by pollen from the same plant or from genetically similar plants, and ensures outcrossing. Gynoecium Gynoecium (, from Ancient Greek , ""gyne"", meaning ""woman"", and , ""oikos"", meaning ""house"") is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower, it consists of (one or"
"of gymnosperms and flowering plants is the germination of a pollen grain after pollination. Like seeds, pollen grains are severely dehydrated before being released to facilitate their dispersal from one plant to another. They consist of a protective coat containing several cells (up to 8 in gymnosperms, 2-3 in flowering plants). One of these cells is a tube cell. Once the pollen grain lands on the stigma of a receptive flower (or a female cone in gymnosperms), it takes up water and germinates. Pollen germination is facilitated by hydration on the stigma, as well as by the structure and physiology"
"It is thought that plant hormones, such as ethylene and cytokines, control the stomatal developmental response to the environmental conditions. Accumulation of these hormones appears to cause increased stomatal density such as when the plants are kept in closed environments. Epidermis (botany) The epidermis (from the Greek ""ἐπιδερμίς"", meaning ""over-skin"") is a single layer of cells that covers the leaves, flowers, roots and stems of plants. It forms a boundary between the plant and the external environment. The epidermis serves several functions: it protects against water loss, regulates gas exchange, secretes metabolic compounds, and (especially in roots) absorbs water and"
"outside of the stigmas or the upper part of the style, which serve as a 'receptaculum pollinis'. Increased surface area and irregularity of the pollen receptacle, caused by swellings, hairs, grooves or ridges often ensure a more efficient pollen deposition. After elongation of the style, animals transport the pollen to flowers in the female or receptive stage with exposed stigmatic surfaces. A pollen catapult mechanism is present in the genera ""Molopanthera"" and ""Posoqueria"" (tribe Posoquerieae) that projects a spherical pollen mass onto visiting sphingidae.Heterodistyly is another mechanism to avoid inbreeding and is widely present in the Rubiaceae family. The tribes"