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Preissia
''Marchantia quadrata'' is a species of liverwort, a simple non-flowering plant that grows as a flat, green, leaf-like structure (thallus) typically found on damp rocks and soil along stream banks in the Northern Hemisphere. The species was originally classified in its own genus ''Preissia'' due to its distinctive features, including larger spores and lack of the specialised cup-like reproductive structures common in other liverworts, but genetic studies have shown it belongs within the genus ''Marchantia''. Like most liverworts, it reproduces both sexually, through separate male and female plants that produce umbrella-like reproductive structures, and through regeneration from fragments. The species prefers slightly drier habitats than its relatives and shows significant genetic variation across its range, suggesting it may comprise several distinct but closely related species. Taxonomy and evolution ''Marchantia quadrata'' was originally described as a distinct genus, ''Preissi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scop
A ( or ) was a poet as represented in Old English poetry. The scop is the Old English counterpart of the Old Norse ', with the important difference that "skald" was applied to historical persons, and scop is used, for the most part, to designate oral poets ''within'' Old English literature. Very little is known about scops, and their historical existence is questioned by some scholars. Functions The scop, like the similar gleeman, was a reciter of poetry. The scop, however, was typically attached to a court on a relatively permanent basis. There, he most likely received rich gifts for his performances. The performances often featured the recitation of recognisable texts such as the "old pagan legends of the Germanic tribes." However, the scop's duties also included ''composing'' his own poetry in different situations, the eulogizing of his master. While some scops moved from court to court, they were (generally speaking) less nomadic than the gleemen and had positions of gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clade
In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy adopted by most biological fields. The common ancestor may be an individual, a population, or a species (extinct or Extant taxon, extant). Clades are nested, one in another, as each branch in turn splits into smaller branches. These splits reflect evolutionary history as populations diverged and evolved independently. Clades are termed ''monophyletic'' (Greek: "one clan") groups. Over the last few decades, the cladistic approach has revolutionized biological classification and revealed surprising evolutionary relationships among organisms. Increasingly, taxonomists try to avoid naming Taxon, taxa that are not clades; that is, taxa that are not Monophyly, monophyletic. Some of the relationships between organisms that the molecul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Capsule (fruit)
In botany, a capsule is a type of simple, dry, though rarely fleshy dehiscent fruit produced by many species of angiosperms ( flowering plants). Origins and structure The capsule (Latin: ''capsula'', small box) is derived from a compound (multicarpellary) ovary. A capsule is a structure composed of two or more carpels. In (flowering plants), the term locule (or cell) is used to refer to a chamber within the fruit. Depending on the number of locules in the ovary, fruit can be classified as uni-locular (unilocular), bi-locular, tri-locular or multi-locular. The number of locules present in a gynoecium may be equal to or less than the number of carpels. The locules contain the ovules or seeds and are separated by septa. Dehiscence In most cases the capsule is dehiscent, i.e. at maturity, it splits apart (dehisces) to release the seeds within. A few capsules are indehiscent, for example those of '' Adansonia digitata'', '' Alphitonia'', and '' Merciera''. Capsules are often ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporophyte
A sporophyte () is one of the two alternation of generations, alternating multicellular organism, multicellular phases in the biological life cycle, life cycles of plants and algae. It is a diploid multicellular organism which produces asexual Spore, spores. This stage Alternation of generations, alternates with a multicellular haploid gametophyte phase. Life cycle The sporophyte develops from the zygote produced when a haploid egg cell is fertilized by a haploid sperm and each sporophyte cell therefore has a double set of chromosomes, one set from each parent. All Embryophyta, land plants, and most multicellular algae, have life cycles in which a multicellular diploid sporophyte phase alternates with a multicellular haploid gametophyte phase. In the Spermatophyte, seed plants, the largest groups of which are the gymnosperms (bare seeds) and angiosperms (fruiting plants), the sporophyte phase is more prominent than the gametophyte, and is the familiar green plant with its roots, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Growing Season
A season is a division of the year marked by changes in weather, ecology, and the amount of daylight. The growing season is that portion of the year in which local conditions (i.e. rainfall, temperature, daylight) permit normal plant growth. While each plant or crop has a specific growing season that depends on its genetic adaptation, growing seasons can generally be grouped into macro-environmental classes. Axial tilt of the Earth inherently affect growing seasons across the globe. Geography Geographic conditions have major impacts on the growing season for any given area. Latitude is one of the major factors in the length of the growing season. The further from the equator one goes, the angle of the Sun gets lower in the sky. Consequently, sunlight is less direct and the low angle of the Sun means that soil takes longer to warm during the spring months, so the growing season begins later. The other factor is altitude, with high elevations having cooler temperatures which short ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archegonia
An archegonium (: archegonia), from the Ancient Greek ''ἀρχή'' ("beginning") and ''γόνος'' ("offspring"), is a multicellular structure or organ of the gametophyte phase of certain plants, producing and containing the ovum or female gamete. The corresponding male organ is called the antheridium. The archegonium has a long neck canal or venter and a swollen base. Archegonia are typically located on the surface of the plant thallus, although in the hornworts they are embedded. __TOC__ Bryophytes In bryophytes and other cryptogams, sperm reach the archegonium by swimming in water films, whereas in Pinophyta and angiosperms, the pollen are delivered by wind or animal vectors and the sperm are delivered by means of a pollen tube. In the moss ''Physcomitrella patens'', archegonia are not embedded but are located on top of the leafy gametophore (s. Figure). The Polycomb protein FIE is expressed in the unfertilized egg cell (right) as the blue colour after GUS staining reveals ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antheridia
An antheridium is a haploid structure or organ producing and containing male gametes (called ''antherozoids'' or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. The androecium is also the collective term for the stamens of flowering plants. Antheridia are present in the gametophyte phase of cryptogams like bryophytes and ferns. Many algae and some fungi, for example, ascomycetes and water moulds, also have antheridia during their reproductive stages. In gymnosperms and angiosperms, the male gametophytes have been reduced to pollen grains, and in most of these, the antheridia have been reduced to a single generative cell within the pollen grain. During pollination, this generative cell divides and gives rise to sperm cells. The female counterpart to the antheridium in cryptogams is the archegonium, and in flowering plants is the gynoecium. An antheridium typically consists of sterile cells and spermatogenous ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Greenhouse
A greenhouse is a structure that is designed to regulate the temperature and humidity of the environment inside. There are different types of greenhouses, but they all have large areas covered with transparent materials that let sunlight pass and block it as heat. The most common materials used in modern greenhouses for walls and roofs are rigid plastic made of polycarbonate, plastic film made of polyethylene, or glass panes. When the inside of a greenhouse is exposed to sunlight, the temperature increases, providing a sheltered environment for plants to grow even in cold weather. The terms greenhouse, glasshouse, and hothouse are often used interchangeably to refer to buildings used for cultivating plants. The specific term used depends on the material and heating system used in the building. Nowadays, greenhouses are more commonly constructed with a variety of materials, such as wood and polyethylene plastic. A glasshouse, on the other hand, is a traditional type of greenhouse ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tracheid
A tracheid is a long and tapered Lignin, lignified cell in the xylem of Tracheophyta, vascular plants. It is a type of conductive cell called a tracheary element. Angiosperms also use another type of conductive cell, called vessel elements, to transport water through the xylem. The main functions of tracheid cells are to Transpiration, transport water and inorganic salts, and to provide structural support for trees. There are often Pit (botany), pits on the cell walls of tracheids, which allows for water flow between cells. Tracheids are dead at functional maturity and do not have a protoplast. The wood (softwood) of gymnosperms such as pines and other conifers is mainly composed of tracheids. Tracheids are also the main conductive cells in the primary xylem of ferns. The tracheid was first named by the German botanist Carl Gustav Sanio in 1863, from the German ''Tracheide''. Evolution Tracheids were the main conductive cells found in early vascular plants. In the first 140� ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chlorophyll
Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words (, "pale green") and (, "leaf"). Chlorophyll allows plants to absorb energy from light. Those pigments are involved in oxygenic photosynthesis, as opposed to bacteriochlorophylls, related molecules found only in bacteria and involved in anoxygenic photosynthesis. Chlorophylls absorb light most strongly in the blue portion of the electromagnetic spectrum as well as the red portion. Conversely, it is a poor absorber of green and near-green portions of the spectrum. Hence chlorophyll-containing tissues appear green because green light, diffusively reflected by structures like cell walls, is less absorbed. Two types of chlorophyll exist in the photosystems of green plants: chlorophyll ''a'' and ''b''. History Chlorophyll was first isolated and named by Joseph Bienaimé Caventou and Pierre Joseph Pelletier in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marchantia Quadrata, Liezen, Austria 2
''Marchantia'' is a genus of liverworts in the family Marchantiaceae and the order Marchantiales. The genus was named by French botanist Jean Marchant after his father. The thallus of ''Marchantia'' shows differentiation into two layers: an upper photosynthetic layer with a well-defined upper epidermis with pores and a lower storage layer. The thallus features tiny cup-like structures called gemma cups, containing gemmae, small packets of tissue that are used for asexual reproduction. The combination of barrel-shaped pores and the circular shape of the gemma cups are diagnostic of the genus. Multicellular purple colored scales with single cell thickness and unicellular rhizoids are present on the ventral surface of the thallus. Reproduction ''Marchantia'' can reproduce both sexually and asexually. Sexual reproduction involves sperm from antheridia on the male plant fertilizing an ovum (egg cell) in the archegonium of a female plant. The antheridia and archegonia are borne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
