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Tunica (biology)
In biology, a tunica (, ; ) is a layer, coat, sheath, or similar covering. The word came to English from the New Latin of science and medicine. Its literal sense is about the same as that of the word ''tunic'', with which it is cognate. In biology one of its senses used to be the taxonomic name of a genus of plants, but the nomenclature has been revised and those plants are now included in the genus ''Petrorhagia''. In modern biology in general, ''tunica'' occurs as a technical or anatomical term mainly in botany and zoology. It usually refers to membranous structures that line or cover particular organs. In many such contexts ''tunica'' is used interchangeably with ''tunic'' according to preference. An organ or organism that has a tunic(a) may be said to be ''tunicate'', as in a ''tunicate bulb''. This adjective ''tunicate'' is not to be confused with the noun ''tunicate'', which refers to a member of the subphylum '' Tunicata''. Botanical and related usages In botany there are s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biology
Biology is the scientific study of life. It is a natural science with a broad scope but has several unifying themes that tie it together as a single, coherent field. For instance, all organisms are made up of cells that process hereditary information encoded in genes, which can be transmitted to future generations. Another major theme is evolution, which explains the unity and diversity of life. Energy processing is also important to life as it allows organisms to move, grow, and reproduce. Finally, all organisms are able to regulate their own internal environments. Biologists are able to study life at multiple levels of organization, from the molecular biology of a cell to the anatomy and physiology of plants and animals, and evolution of populations.Based on definition from: Hence, there are multiple subdisciplines within biology, each defined by the nature of their research questions and the tools that they use. Like other scientists, biologists use the sc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Angiosperm
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants that produce their seeds enclosed within a fruit. They are by far the most diverse group of land plants with 64 orders, 416 families, approximately 13,000 known genera and 300,000 known species. Angiosperms were formerly called Magnoliophyta (). Like gymnosperms, angiosperms are seed-producing plants. They are distinguished from gymnosperms by characteristics including flowers, endosperm within their seeds, and the production of fruits that contain the seeds. The ancestors of flowering plants diverged from the common ancestor of all living gymnosperms before the end of the Carboniferous, over 300 million years ago. The closest fossil relatives of flowering plants are uncertain and contentious. The earliest angiosperm fossils are in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunica Adventitia
The tunica externa (New Latin "outer coat"), also known as the tunica adventitia (New Latin "additional coat"), is the outermost tunica (layer) of a blood vessel, surrounding the tunica media. It is mainly composed of collagen and, in arteries, is supported by external elastic lamina. The collagen serves to anchor the blood vessel to nearby organs, giving it stability. The three layers of the blood vessels are: an inner tunica intima, a middle tunica media, and an outer tunica externa. Structure The tunica externa is made from collagen and elastic fibers in a loose connective tissue. This is secreted by fibroblasts. Function The tunica externa provides basic structural support to blood vessels. It prevents vessels from expanding too much from internal blood pressure, particularly arteries. It is also relevant in controlling vascular flow in the lungs. Clinical significance A common pathological disorder concerning the tunica externa is scurvy, also known as vitamin C defic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunica Intima
The tunica intima (New Latin "inner coat"), or intima for short, is the innermost tunica (layer) of an artery or vein. It is made up of one layer of endothelial cells and is supported by an internal elastic lamina. The endothelial cells are in direct contact with the blood flow. The three layers of a blood vessel are an inner layer (the tunica intima), a middle layer (the tunica media), and an outer layer (the tunica externa). In dissection, the inner coat (tunica intima) can be separated from the middle (tunica media) by a little maceration, or it may be stripped off in small pieces; but, because of its friability, it cannot be separated as a complete membrane. It is a fine, transparent, colorless structure which is highly elastic, and, after death, is commonly corrugated into longitudinal wrinkles. Structure The structure of the tunica intima depends on the blood vessel type. Elastic arteries – A single layer of Endothelial and a supporting layer of elastin-rich col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morphology (biology)
Morphology is a branch of biology dealing with the study of the form and structure of organisms and their specific structural features. This includes aspects of the outward appearance ( shape, structure, colour, pattern, size), i.e. external morphology (or eidonomy), as well as the form and structure of the internal parts like bones and organs, i.e. internal morphology (or anatomy). This is in contrast to physiology, which deals primarily with function. Morphology is a branch of life science dealing with the study of gross structure of an organism or taxon and its component parts. History The etymology of the word "morphology" is from the Ancient Greek (), meaning "form", and (), meaning "word, study, research". While the concept of form in biology, opposed to function, dates back to Aristotle (see Aristotle's biology), the field of morphology was developed by Johann Wolfgang von Goethe (1790) and independently by the German anatomist and physiologist Karl Friedr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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. Description 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, 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. Puffballs 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 d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a 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 the embryo sac is fertilized by sperm from pollen, forming a zygote. The embryo within a seed develops from the zygote, and grows within the mother plant to a certain size before growth is halted. The seed coat arises from the integuments of the ovule. Seeds have been an important development in the reproduction and success of vegetable gymnosperm and angiosperm plants, relative to more primitive plants such as ferns, mosses 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 Climate is the long-term weather p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gladiolus
''Gladiolus'' (from Latin, the diminutive of ''gladius'', a sword) is a genus of perennial cormous flowering plants in the iris family (Iridaceae). It is sometimes called the 'sword lily', but is usually called by its generic name (plural ''gladioli''). The genus occurs in Asia, Mediterranean Europe, South Africa, and tropical Africa. The center of diversity is in the Cape Floristic Region.Goldblatt, P. &, J.C. Manning. ''Gladiolus'' in Southern Africa : Systematics, Biology, and Evolution. Fernwood Press, Cape Town; 1998. The genera ''Acidanthera'', ''Anomalesia'', ''Homoglossum'', and ''Oenostachys'', formerly considered distinct, are now included in ''Gladiolus''. Description Gladioli grow from round, symmetrical corms (similar to crocuses) that are enveloped in several layers of brownish, fibrous tunics. Their stems are generally unbranched, producing 1 to 9 narrow, sword-shaped, longitudinal grooved leaves, enclosed in a sheath. The lowest leaf is shortened to a catap ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watsonia (plant)
''Watsonia'' (bugle lily) is a genus of plants in the family Iridaceae, subfamily Crocoideae. Watsonias are native to southern Africa (South Africa, Lesotho, Eswatini). The genus is named after Sir William Watson, an 18th-century British botanist. Diversity There are 56 accepted species in southern Africa, with two varieties and about 112 names either unresolved or regarded as synonyms. All are perennial herbs growing from corms and producing erect spikes of showy flowers. Most are fynbos plants, adapted to a Mediterranean-type climate, but some occur along the eastern and inland areas of the country and adapted to a wider range of conditions, mainly continental climate with summer rainfall. Many species occur mainly in the mountains, though some occur in sandy flats and marshy areas. Cultivation The most commonly cultivated species is the pink-flowered '' Watsonia borbonica'' and its white mutant 'Arderne's White'. These were crossed with '' Watsonia meriana'' and other spec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iridaceae
Iridaceae is a family of plants in order Asparagales, taking its name from the irises, meaning rainbow, referring to its many colours. There are 66 accepted genera with a total of c. 2244 species worldwide (Christenhusz & Byng 2016). It includes a number of other well known cultivated plants, such as freesias, gladioli and crocuses. Members of this family are perennial plants, with a bulb, corm or rhizome. The plants grow erect, and have leaves that are generally grass-like, with a sharp central fold. Some examples of members of this family are the blue flag and yellow flag. Name and history The family name is based on the genus ''Iris'', the largest and best known genus in Europe. This genus dates from 1753, when it was coined by Swedish botanist, Carl Linnaeus. Its name derives from the Greek goddess, Iris, who carried messages from Olympus to earth along a rainbow, whose colours were seen by Linnaeus in the multi-hued petals of many of the species. The family is curr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boophone
''Boophone'' is a small genus of herbaceous, perennial and bulbous plants in the Amaryllis family (Amaryllidaceae, subfamily Amaryllidoideae.) It consists of two confirmed species distributed across South Africa to Kenya and Uganda. It is closely related to '' Crossyne'', a genus whose species have prostrate leaves. They are drought tolerant but not cold-hardy, and are very poisonous to livestock. Taxonomy ''Boophone'' is the single genus in subtribe Boophoninae, in the Amaryllideae tribe. Phylogeny Boophoninae are placed within Amaryllideae as follows, based on their phylogenetic relationship: Species The list of ''Boophone'' species, with their complete scientific name, authority, and geographic distribution is given below.Royal Botanical Gardens, KewWorld Checklist of Monocotyledons: ''Boophone '' Accessed May 16, 2009. Etymology William Herbert wrote the name of this genus with three different orthographies: "Boophane" in 1821; "Buphane" and "Buphone" in 182 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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