|
Andreaea Blyttii
''Andreaea blyttii'', also commonly known as Blytt's rock moss, is a moss belonging to the family Andreaeaceae, commonly known as rock moss, granite moss, or lantern moss because of this family's unique sporangium. It is part of the genus Andreaea which is known for forming dark brownish or reddish-black carpets in high elevations. This species was first described by Schimper in 1855. Description The shoots of ''A. blyttii'' vary in length. They are distinctively known for being small and dark red or black. They form tuffs and have acrocarpus growth. Depending on the frequency of desiccation, the branching pattern can vary from unbranched to irregularly branched. The number of leaves per shoot increases in dry environments. The stem walls are made up of pigmented cells and the stem lacks a conducting strand which is a character of the genus '' Andreaea''. Rhizoids are attached at the base of the shoot. The spores are uniquely small in this species and grow into a thalloid pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andreaeaceae
Andreaeaceae is a family of mosses which includes two genera, ''Andreaea'', containing about 100 species, and the genus ''Acroschisma''. The Andreaeaceae prefer rocky habitats ranging from tropical to arctic climates, on which they form tufted colonies, typically with reddish to blackish shoots. The capsules lack the peristome mechanism and dehisce longitudinally to release the spores, resulting in a paper-lantern appearance. It was named by Jakob Friedrich Ehrhart in honour of his friend J.G.R. Andreae.Transactions of the Linnean Society of London, Volume 10, p. 381, Linnean Society of London The Linnean Society of London is a learned society dedicated to the study and dissemination of information concerning natural history, evolution, and taxonomy. It possesses several important biological specimen, manuscript and literature colle ..., 1811 References External links * Zander, Richard H. 2007. ''Bryophyte Flora of North America'' Andreaeaceae Moss families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andreaea
''Andreaea'' is a genus of rock mosses described by Johann Hedwig in 1801. They are small, delicate acrocarpous mosses (meaning that the capsules are formed at the tips of vertical branches) that form dark brown or reddish cushions on wet siliceous rocks in mountainous areas. The capsule lacks the peristome teeth and operculum of other mosses, and opens by splitting along 4 vertical slits, the four valves remaining joined at the base and apex. The capsule of ''Andreaea'' has no seta, but the sporophyte (''Spf'' in the diagram below) instead is supported by a pseudopodium (''ps'') derived from gametophyte tissue, as in ''Sphagnum'' and the columella is enclosed within the sporangium. The spores germinate to give thalloid Thallus (plural: thalli), from Latinized Ancient Greek, Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some Marchantiophyta, liverworts, lichens, and the Myxogastr ... proton ... [...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 A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and special ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andreaea Nivalis
''Andreaea nivalis'', also known as snow rock-moss, is a species of moss in the Andreaea family found in Alaska, California, Oregon, Washington, Greenland, Spain, Japan, Russia and Poland. It is black and reddish, dioicous, and grows on wet, acidic rocks. It is threatened by droughts and global warming, and is a near-threatened species on the IUCN red list. Description ''Andreaea nivalis'' was first described in 1811. It is black and reddish, and grows in dense cushions. Its leaves can be secund to falcate-secund, meaning they can be sickle-shaped, and curved towards one side. They are mostly subulate, meaning they are awl-shaped. The leaves are mainly falcate-secund when dry. When moist, they are more spread out than when dry. The leaves have a strong costa, and they can have a width of or more, and a length of or more. ''Andreaea nivalis'' has sharp laminal papillae on its dorsal side, which almost reach to its base, and a very short fruit stalk. Unlike other mosses in its spe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gneiss
Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures and pressures than schist. Gneiss nearly always shows a banded texture characterized by alternating darker and lighter colored bands and without a distinct cleavage. Gneisses are common in the ancient crust of continental shields. Some of the oldest rocks on Earth are gneisses, such as the Acasta Gneiss. Description Orthogneiss from the Czech Republic In traditional English and North American usage, a gneiss is a coarse-grained metamorphic rock showing compositional banding (gneissic banding) but poorly developed schistosity and indistinct cleavage. In other words, it is a metamorphic rock composed of mineral grains easily seen with the unaided eye, which form obvious compositional layers, but which has only a weak tendency to fracture ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granite
Granite () is a coarse-grained (phaneritic) intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly cools and solidifies underground. It is common in the continental crust of Earth, where it is found in igneous intrusions. These range in size from dikes only a few centimeters across to batholiths exposed over hundreds of square kilometers. Granite is typical of a larger family of ''granitic rocks'', or ''granitoids'', that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by the relative percentages of quartz, alkali feldspar, and plagioclase (the QAPF classification), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain mica or amphibole minerals, though a few (known as leucogranites) contain almost no dark minerals. Granite is nearly alway ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adjectival term applied to anatomical structures which are made primarily of calcium carbonate, in animals such as gastropods, i.e., snails, specifically about such structures as the operculum, the clausilium, and the love dart. The term also applies to the calcium carbonate tests of often more or less microscopic Foraminifera. Not all tests are calcareous; diatoms and radiolaria have siliceous tests. The molluscs are calcareous, as are calcareous sponges ( Porifera), that have spicules which are made of calcium carbonate. In botany ''Calcareous grassland'' is a form of grassland characteristic of soils containing much calcium carbonate from underlying chalk or limestone rock. In medicine The term is used in pathology, for example i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporic Meiosis
Alternation of generations (also known as metagenesis or heterogenesis) is the predominant type of life cycle in plants and algae. It consists of a multicellular haploid sexual phase, the gametophyte, which has a single set of chromosomes alternating with a multicellular diploid asexual phase, the sporophyte which has two sets of chromosomes. A mature sporophyte produces haploid spores by meiosis, a process which reduces the number of chromosomes to half, from two sets to one. The resulting haploid spores germinate and grow into multicellular haploid gametophytes. At maturity, a gametophyte produces gametes by mitosis, the normal process of cell division in eukaryotes, which maintains the original number of chromosomes. Two haploid gametes (originating from different organisms of the same species or from the same organism) fuse to produce a diploid zygote, which divides repeatedly by mitosis, developing into a multicellular diploid sporophyte. This cycle, from gametophyte to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bryophyte
The Bryophyta s.l. are a proposed taxonomic division containing three groups of non-vascular land plants (embryophytes): the liverworts, hornworts and mosses. Bryophyta s.s. consists of the mosses only. They are characteristically limited in size and prefer moist habitats although they can survive in drier environments. The bryophytes consist of about 20,000 plant species. Bryophytes produce enclosed reproductive structures (gametangia and sporangia), but they do not produce flowers or seeds. They reproduce sexually by spores and asexually by fragmentation or the production of gemmae. Though bryophytes were considered a paraphyletic group in recent years, almost all of the most recent phylogenetic evidence supports the monophyly of this group, as originally classified by Wilhelm Schimper in 1879. The term ''bryophyte'' comes . Terminology The term "Bryophyta" was first suggested by Braun in 1864. G.M. Smith placed this group between Algae and Pteridophyta. Features The d ... [...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 reveals. S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sporophyte
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage 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 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 seed plants, the largest groups of which are the gymnosperms and flowering plants (angiosperms), the sporophyte phase is more prominent than the gametophyte, and is the familiar green plant with its roots, stem, leaves and cones or flowers. In flowering plants the gametophytes are very reduced in size, and are represented by the germinated pollen and the embryo sac. The sporophyte produces spores (hence t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andreaeopsida
Andreaeaceae is a family of mosses which includes two genera, ''Andreaea'', containing about 100 species, and the genus ''Acroschisma''. The Andreaeaceae prefer rocky habitats ranging from tropical to arctic climates, on which they form tufted colonies, typically with reddish to blackish shoots. The capsules lack the peristome mechanism and dehisce longitudinally to release the spores, resulting in a paper-lantern appearance. It was named by Jakob Friedrich Ehrhart in honour of his friend J.G.R. Andreae.Transactions of the Linnean Society of London, Volume 10, p. 381, Linnean Society of London The Linnean Society of London is a learned society dedicated to the study and dissemination of information concerning natural history, evolution, and taxonomy. It possesses several important biological specimen, manuscript and literature colle ..., 1811 References External links * Zander, Richard H. 2007. ''Bryophyte Flora of North America'' Andreaeaceae Moss families ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
