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Dawsonia Superba
''Dawsonia superba'' is a moss in the class Polytrichaceae that is found in Australia, New Guinea, Malaysia and New Zealand. ''D. superba'' is the tallest self-supporting moss in the world, reaching heights of 60 cm. It has analogous structures to those in vascular plants that support large size, including hydroid and leptoid cells to conduct water and photosynthate, and lamellae that provide gas chambers for more efficient photosynthesis. ''D. superba'' is a member of the class Polytrichopsida, although it has a sporophyte that is unique from other hair-cap mosses. There is some confusion surrounding if ''Dawsonia superba'' and '' Dawsonia longifolia'' are distinct species or refer to the same moss. According to some sources, ''Dawsonia longifolia'' and ''Dawsonia superba'' have been merged. For a long time, both ''D. longifolia'' and ''D. superba'' were used to refer to the same species, with some regional variation in its use. Both terms are still used today. Distribution ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Abel Tasman National Park
Abel Tasman National Park is a New Zealand national park located between Golden Bay and Tasman Bay / Te Tai-o-Aorere at the north end of the South Island. It is named after Abel Tasman, who in 1642 became the first European explorer to sight New Zealand and who anchored nearby in Golden Bay. History The park was founded in 1942, largely through the efforts of ornithologist and author Pérrine Moncrieff to have land reserved for the purpose. Moncrieff served on the park board from 1943 to 1974. The park was opened on the 18 December 1942 to mark the 300th anniversary of Abel Tasman's visit.Historic Event, Evening Post, Wellington, volume=CXXXIV, issue=127, 25 November 1942, Page 3 Those in attendance at the opening ceremony at Tarakohe included Charles van der Plas, as personal representative of the Netherlands' Queen, Wilhelmina. The Queen was made Patron of the park. The idea for the park had been under consideration since June 1938. The Crown set aside , comprising of pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rhizoid
Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be unicellular or multicellular. Evolutionary development Plants originated in aquatic environments and gradually migrated to land during their long course of evolution. In water or near it, plants could absorb water from their surroundings, with no need for any special absorbing organ or tissue. Additionally, in the primitive states of plant development, tissue differentiation and division of labor was minimal, thus specialized water absorbing tissue was not required. The development of specialized tissues to absorb water efficiently and anchor themselves to the ground enabled the spread of plants to the land. Description Rhizoids absorb water mainly by capillary action, in which water moves up between threads of rhizoids and not through e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dawsonia Superba Grev
''Dawsonia'' is the scientific name of several genera of organisms and may refer to: * ''Dawsonia'' (plant), a genus of moss some reaching up to 65 cm (two feet) in length * ''Dawsonia'' (trilobite), an eodiscoid trilobite * ''Dawsonia'' (problematicum), a Palaeozoic problematicum {{Genus disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Archegonium
An archegonium (pl: 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. 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 r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antheridium
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. 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 ti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dioecy
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is biparental reproduction. Dioecy has costs, since only about half the population directly produces offspring. It is one method for excluding self-fertilization and promoting allogamy (outcrossing), and thus tends to reduce the expression of recessive deleterious mutations present in a population. Plants have several other methods of preventing self-fertilization including, for example, dichogamy, herkogamy, and self-incompatibility. Dioecy is a dimorphic sexual system, alongside gynodioecy and androdioecy. In zoology In zoology, dioecious species may be opposed to hermaphroditic species, meaning that an individual is either male or female, in which case the synonym gonochory is more often used. Most animal species are dioeci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protonema
A protonema (plural: protonemata) is a thread-like chain of cells that forms the earliest stage of development of the gametophyte (the haploid phase) in the life cycle of mosses. When a moss first grows from a spore, it starts as a ''germ tube'', which lengthens and branches into a filamentous complex known as a ''protonema'', which develops into a leafy gametophore, the adult form of a gametophyte in bryophytes. Moss spores germinate to form an alga-like filamentous structure called the protonema. It represents the juvenile gametophyte. While the protonema is growing by apical cell division, at some stage, under the influence of the phytohormone cytokinin, buds are induced which grow by three-faced apical cells. These give rise to gametophores, stems and leaf like structures. Bryophytes do not have true leaves ( megaphylls). Protonemata are characteristic of all mosses and some liverworts but are absent from hornworts. Protonemata of mosses are composed of two cell types: chlo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Epiphragm
An epiphragm (from the Ancient Greek ἐπί, '' epi '' " upon, on, over " and φράγμα, '' -phrágma '' "fence") is a temporary structure which can be created by many species of shelled, air-breathing land snails, terrestrial pulmonate gastropod mollusks. It can also be created by freshwater snails when temporary pools dry up. In most species the epiphragm is made of dried mucus, and although it is elastic, it is fairly easily torn when forcibly removing a snail from its substrate. In a few species the epiphragm is thick and quite rigid, being reinforced with calcium carbonate. This kind of epiphragm is very strong and may be difficult to break. Function The epiphragm is created to seal the aperture of the shell against desiccation. It is used when the snail is inactive. Most land snails are only active when the humidity is high such as after rain and at night, and become inactive during dry weather. The main function of the epiphragm is to reduce water loss through th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dawsonia Stem
''Dawsonia'' is the scientific name of several genera of organisms and may refer to: * ''Dawsonia'' (plant), a genus of moss some reaching up to 65 cm (two feet) in length * ''Dawsonia'' (trilobite), an eodiscoid trilobite * ''Dawsonia'' (problematicum), a Palaeozoic problematicum {{Genus disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gametophyte
A gametophyte () is one of the two alternating multicellular phases in the life cycles of plants and algae. It is a haploid multicellular organism that develops from a haploid spore that has one set of chromosomes. The gametophyte is the sexual phase in the life cycle of plants and algae. It develops sex organs that produce gametes, haploid sex cells that participate in fertilization to form a diploid zygote which has a double set of chromosomes. Cell division of the zygote results in a new diploid multicellular organism, the second stage in the life cycle known as the sporophyte. The sporophyte can produce haploid spores by meiosis that on germination produce a new generation of gametophytes. Algae In some multicellular green algae (''Ulva lactuca'' is one example), red algae and brown algae, sporophytes and gametophytes may be externally indistinguishable (isomorphic). In ''Ulva'' the gametes are isogamous, all of one size, shape and general morphology. Land ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Robert Kaye Greville
Dr. Robert Kaye Greville FRSE FLS LLD (13 December 1794 – 4 June 1866) was an English mycologist, bryologist, and botanist. He was an accomplished artist and illustrator of natural history. In addition to art and science he was interested in causes like abolitionism, capital punishment, keeping Sunday special and the temperance movement. He has a mountain in Queensland named after him. Biography Greville was born at Bishop Auckland, Durham, but was brought up in Derbyshire by his parents Dorothy ( Chaloner) and Robert Greville. His father who liked to compose was the rector of the parish church in Edlaston in Derbyshire. Greville had an interest in natural history since he was very young, but he originally studied medicine. Realising that he did not need an income he discarded four years of medical education in London and Edinburgh and decided to concentrated on botany which had been a strong interest when he was a boy. Greville married William Eden, 1st Baron Auckla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dawsonia Longifolia
''Dawsonia longifolia'' is a tall moss, growing to ~60 cm in height. This species may be a synonym of '' D. superba''. Distribution ''Dawsonia longifolia'' may be found in the Philippines, Indonesia, Malaysia Malaysia ( ; ) is a country in Southeast Asia. The federation, federal constitutional monarchy consists of States and federal territories of Malaysia, thirteen states and three federal territories, separated by the South China Sea into two r ..., and Australia. References External links * Polytrichaceae {{moss-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
