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Cycas Micronesica
''Cycas micronesica'' is a species of cycad found on the island of Yap in Micronesia, the Marianas islands of Guam and Rota, and The Republic of Palau. It is commonly known as federico nut or ''fadang'' in Chamorro. The species, previously lumped with ''Cycas rumphii'' and ''Cycas circinalis'', was described in 1994 by Ken Hill. Paleoecological studies have determined that ''C. micronesica'' has been present on the island of Guam for about 9,000 years. It is linked with Lytico-Bodig disease, a condition similar to amyotrophic lateral sclerosis (ALS), due to the neurotoxin BMAA found in its seeds, which were a traditional food source on Guam until the 1960s. The neurotoxin is present due to its symbiosis with cyanobacteria. Description ''Cycas'' ''micronesica'' is a medium-sized tree most commonly 2–5 meters tall but can reach heights up to 15 meters. The tree has a straight palm like trunk ringed with frond scars. Leaves Leaves are 140–180 cm long, flat in sec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ken Hill (botanist)
Kenneth D. Hill (6 August 1948 – 4 August 2010) was an Australian botanist, notable for his work on eucalypts, the systematics, evolution and conservation of the genus ''Cycas'', as well as on botanical informatics. He was born in Armidale, New South Wales. He worked with the National Herbarium of New South Wales from 1983 until retiring in 2004. He was also a senior research scientist with the Royal Botanic Gardens, Sydney The Royal Botanic Garden, Sydney is a heritage-listed major botanical garden, event venue and public recreation area located at Farm Cove on the eastern fringe of the Sydney central business district, in the City of Sydney local government ar .... References 20th-century Australian botanists Australian taxonomists 1948 births 2010 deaths 21st-century Australian botanists Australian Botanical Liaison Officers {{Australia-botanist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviposition
The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typically its form is adapted to functions such as preparing a place for the egg, transmitting the egg, and then placing it properly. For most insects, the organ is used merely to attach the egg to some surface, but for many parasitic species (primarily in wasps and other Hymenoptera), it is a piercing organ as well. Some ovipositors only retract partly when not in use, and the basal part that sticks out is known as the scape, or more specifically oviscape, the word ''scape'' deriving from the Latin word '' scāpus'', meaning "stalk" or "shaft". In insects Grasshoppers use their ovipositors to force a burrow into the earth to receive the eggs. Cicadas pierce the wood of twigs with their ovipositors to insert the eggs. Sawflies slit the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsporangia
Microsporangia are sporangia that produce microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fern genus ''Azolla''. In gymnosperms and angiosperm anthers, the microsporangia produce microsporocytes, the microspore mother cells, which then produce four microspores through the process of meiosis. Microsporocytes are produced in the microsporangia of gymnosperm cones and the anthers of angiosperms. They are diploid microspore mother-cells, which then produce four haploid microspores through the process of meiosis. These become pollen grains, within which the microspores divide twice by mitosis to produce a very simple gametophyte. Heterosporous plants that produced microspores in microsporangia and megaspores in separate megasporangia evolved independently in several plant groups during the Devonian period. Fossils of these plants sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Anatrachyntis
''Anatrachyntis'' is a genus of moths in the family Cosmopterigidae. Some authors include it in '' Pyroderces''. Species *'' Anatrachyntis acris'' (Meyrick, 1911) (the Seychelles) *'' Anatrachyntis aellotricha'' (Meyrick, 1889) (New Zealand) (often in '' Pyroderces'') *'' Anatrachyntis amphisaris'' (Meyrick, 1922) (Sri Lanka) *'' Anatrachyntis anaclastis'' (Meyrick, 1897) (Australia, Queensland) *'' Anatrachyntis anoista'' (Bradley, 1956) (Lord Howe Island) *'' Anatrachyntis badia'' – Florida pink scavenger *'' Anatrachyntis bicincta'' (Ghesquière, 1940) (Zaire) *'' Anatrachyntis biorrhizae'' Sinev, 1986 (Russia, Primorje) *'' Anatrachyntis calefacta'' (Meyrick, 1922) (India) *'' Anatrachyntis carpophila'' (Ghesquière, 1940) (Zaire) *'' Anatrachyntis cecidicida'' (Ghesquière, 1940) (Zaire) *'' Anatrachyntis centropecta'' (Meyrick, 1931) (Peninsular Malaysia) *'' Anatrachyntis centrophanes'' (Meyrick, 1915) (India) *'' Anatrachyntis coriacella'' (Snellen, 1901) (Indonesia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsporangia
Microsporangia are sporangia that produce microspores that give rise to male gametophytes when they germinate. Microsporangia occur in all vascular plants that have heterosporic life cycles, such as seed plants, spike mosses and the aquatic fern genus ''Azolla''. In gymnosperms and angiosperm anthers, the microsporangia produce microsporocytes, the microspore mother cells, which then produce four microspores through the process of meiosis. Microsporocytes are produced in the microsporangia of gymnosperm cones and the anthers of angiosperms. They are diploid microspore mother-cells, which then produce four haploid microspores through the process of meiosis. These become pollen grains, within which the microspores divide twice by mitosis to produce a very simple gametophyte. Heterosporous plants that produced microspores in microsporangia and megaspores in separate megasporangia evolved independently in several plant groups during the Devonian period. Fossils of these plants sho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megasporangia
A sporangium (; from Late Latin, ) is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. Virtually all plants, fungi, and many other lineages form sporangia at some point in their life cycle. Sporangia can produce spores by mitosis, but in nearly all land plants and many fungi, sporangia are the site of meiosis and produce genetically distinct haploid spores. Fungi In some phyla of fungi, the sporangium plays a role in asexual reproduction, and may play an indirect role in sexual reproduction. The sporangium forms on the sporangiophore and contains haploid nuclei and cytoplasm. Spores are formed in the sporangiophore by encasing each haploid nucleus and cytoplasm in a tough outer membrane. During asexual reproduction, these spores are dispersed via wind and germinate into haploid hyphae. Although sexual reproduction in fungi varies between phyla, for some fungi the sporangium plays an indirect role in sexual rep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ovule
In seed plants, the ovule is the structure that gives rise to and contains the female reproductive cells. It consists of three parts: the ''integument'', forming its outer layer, the ''nucellus'' (or remnant of the megasporangium), and the female gametophyte (formed from a haploid megaspore) in its center. The female gametophyte — specifically termed a ''megagametophyte''— is also called the ''embryo sac'' in angiosperms. The megagametophyte produces an egg cell for the purpose of fertilization. The ovule is a small structure present in the ovary. It is attached to the placenta by a stalk called a funicle. The funicle provides nourishment to the ovule. Location within the plant In flowering plants, the ovule is located inside the portion of the flower called the gynoecium. The ovary of the gynoecium produces one or more ovules and ultimately becomes the fruit wall. Ovules are attached to the placenta in the ovary through a stalk-like structure known as a ''funiculus'' ... [...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 dioecious (gon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycad
Cycads are seed plants that typically have a stout and woody (ligneous) trunk (botany), trunk with a crown (botany), crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for Arecaceae, palms or ferns, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their fertilization, unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobilus, strobili), somewhat similar to conife ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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