Herkogamy is a common strategy employed by hermaphroditic angiosperms to reduce sexual interference between male anthers and female stigma function. Herkogamy differs from other such strategies e.g. dichogamy by supplying a spatial separation of the anthers and stigma. Two forms of herkogamy are most common 1. Approach Herkogamy pin is the presentation of the stigma above the level of the anthers. This arrangement of sex organs causes floral visitors to first contact the stigma, before removing pollen from the anthers. This form of herkogamy is considered to be common, and is associated with a large, diverse fauna of floral visitors pollinators. 2. Reverse Herkogamy thrum is displayed when the stigma is recessed below the level of the anthers. This arrangement causes floral visitors to first contact the anthers before the stigma. For this reason, reverse herkogamy is believed to facilitate greater pollen export than approach herkogamy. This type of sex organ arrangement is typically associated with Lepidopteran moths and butterflies pollination. References cite book title Diversity and evolutionary biology of tropical flowers Cambridge tropical biology series year 1996 publisher Cambridge University Press isbn 0521565103, 9780521565103 pages 194 195 url http books.google.co.in books?id 8 DfMSS9r9cC&pg PA194&dq Herkogamy&hl en v onepage&q Herkogamy&f false author Peter K. Endress accessdate 25 February 2012 Category Pollination Category Plant morphology de Herkogamie fr Herkogamie no Herkogami sr ... more details
wiktionary File Sunflower 2007.JPG thumb right The heterogamous sunflower head is made up of two types of florets the ray florets near the edge are bilaterally symmetrical with one long petal, and the disk florets in the centre are radially symmetrical with five small petals. File Cichorium intybus alvesgaspar1.jpg thumb right The homogamous chicory flower head is made up of bilaterally symmetrical ray florets, each with one long petal. Homogamy is used in biology in three separate senses Inbreeding can be referred to as homogamy. ref Walker, P.M.B. ed. 1988. The Wordsworth Dictionary of Science and Technology . W. R. Chambers Ltd. and Cambridge University Press. ref Homogamy refers to the maturation of male and female reproductive organs at the same time, which is also known as simultaneous or synchronous hermaphrodite hermaphrodism and is the antonym of dichogamy . Many flowers appear to be homogamous but some of these may not be strictly functionally homogamous, because for various reasons male and female reproduction do not completely overlap. ref cite journal author Bell, S.A. Cresswell, J.E. year 1998 title The phenology of gender in homogamous flowers temporal change in the residual sex function of flowers of Oil seed Rape Brassica napus journal Functional Ecology volume 12 issue 2 pages 298 306 url http dx.doi.org 10.1046 j.1365 2435.1998.00190.x ref In the Asteraceae daisy family , the flower heads are made up of many small flowers called florets, and are either homogamous or heterogamous. Heterogamous heads are made up of two types of florets, ray florets near the edge and disk florets in the center. Homogamous heads are made up of just one type of floret, either all ray florets or all disk florets. References Reflist External links category pollination category reproduction biol stub ... more details
of the plant sexuality of flowering plants angiosperms , there are two forms of dichogamy protogyny ... function. Historically, dichogamy has been regarded as a mechanism for reducing inbreeding e.g. ... self compatible SC plants Bertin, 1993 . This finding led to a reinterpretation of dichogamy as a more ..., 1996 Harder & Wilson, 1998 Barrett, 2002 . Dichogamy may reduce between flower interference by minimizing .... 2000 demonstrated experimentally that dichogamy both reduced rates of self fertilization and enhanced ... that indicated that dichogamy might increase male pollination success was the study performed by Dai and Galloway. ref name Dai cite journal title Do dichogamy and herkogamy reduce sexual interference ... year 1985 cite journal doi 10.2307 2445372 author Bertin, R.I. title Incidence of monoecy and dichogamy ... title Dichogamy in angiosperms journal Bot. Rev. volume 59 pages 112 52 year 1993 cite book author Darwin ... of interference between the presentation of pollen and stigmas in angiosperms I. Dichogamy journal ... more details
File Andrei Bolotov.jpg thumb Andrey Bolotov Andrey Timofeyevich Bolotov 18 October 1738 16 October 1833 was the most distinguished Russia n agriculturist of the 18th century. Bolotov was born and spent most of his adult life in the family estate of Dvoryaninovo, in the Tula, Russia Tula guberniya region to the south of Moscow . He was brought up by his parents in Livland , where his father s regiment was stationed. After taking part in the Seven Years War he settled into retirement in Dvoryaninovo. During his life there, he brought out a pioneering manual on crop rotation and elaborated an innovative system of pomology which included more than 600 cultivar s of apple and pear. Always interested in plant breeding , Bolotov discovered dichogamy of apple trees and pointed out to the advantages of cross pollination . Bolotov s works brought him to the attention of Count Orlov , who asked him to manage the neighbouring estate of Bobriki , where Catherine II of Russia Catherine II s illegitimate son, Count Bobrinsky , was being raised. Bolotov turned Bobriki into the most up to date agricultural estate in provincial Russia and ensured the keen interest which later Counts Bobrinsky would take in agriculture. Bolotov was also active in the Free Economic Society , which published his treatise on forestry . Together with Nikolay Novikov , he edited the journals The Village Resident 1778 79 and The Magazine of Economics 1780 89 , which brought him the income of 400 roubles a year, a very considerable sum for the time. His extensive memoirs, entitled Life and Adventures of Andrei Bolotov, in 26 parts and written between 1789 and 1816, went through several editions and were translated into English. Bolotov died in Dvoryaninovo aged 96. References . . . . . ., 1949 Andrei R zikov Persondata Metadata see Wikipedia Persondata . NAME Bolotov, Andrey ALTERNATIVE NAMES SHORT DESCRIPTION DATE OF BIRTH 18 October 1738 PLACE OF BIRTH DA ... more details
merge Pollination discuss Talk THIS PAGE Merger proposal date July 2010 Xenogamy is the transfer of pollen grain s from anther to the stigma botany stigma of a different plant. This is the only type of pollination which during pollination brings genetically different types of pollen grains to the stigma. ref cite book title Biology textbook for class XII year 2006 publisher Nation Council of Educational Research and Training isbn 81 7450 639 X url http ncertbooks.prashanthellina.com class 12.Biology.Biology 02SEXUAL 20REPRODUCTION 20IN 20FLOWERING 20PLANTS.pdf page 28 ref The term xenogamy along with geitonogamy & autogamy was first suggested by Kerner in 1876. ref cite book last Darwin first Charles title More Letters of Charles Darwin, Volume 2 publisher Echo Library isbn 1406804827, 9781406804829 url http books.google.co.in books?id X9vMhLOiTmQC&pg PA668&dq Xenogamy&hl en v onepage&q Xenogamy&f false accessdate 25 February 2012 page 668 ref Cross pollination involves the transfer of pollen grains from the flower of one plant to the stigma of the flower of another plant. It is also called Xenogamy Gk. xenos strange, gamos marriage . The main characteristics which facilitate cross pollination are Br Herkogamy Flowers possess some mechanical barrier on their stigmatic surface to avoid self pollination, e.g presence of gynostegium and pollinia in Calotropis . Br Dichogamy Pollen and stigma of the flower mature at different times to avoid self pollination. Br Self incompatibility in plants Self incompatibility In same plants, the mature pollen fall on the receptive stigma of the same flower but fail to bring about self pollination. Br Male sterility The pollen grains of some plants are not functional. Such plants set seeds only after cross pollination. Br Plant sexuality Dioecism Cross pollination always occurs when the plants are unisexual and dioecious , i.e., male and female flowers occur on separate plants, e.g., Papaya, some cucurbits, etc. Br Heterostyly The flo ... more details
taxobox name Tricyrtis image Tricyrtis hirta blossom top aka .jpg image caption Tricyrtis hirta regnum Plantae unranked divisio Angiosperms unranked classis Monocots ordo Liliales familia Liliaceae subfamilia Calochortoideae genus Tricyrtis genus authority Nathaniel Wallich Wall. subdivision ranks Species subdivision See text. Tricyrtis is a genus biology genus of the botany botanical family biology family Liliaceae , known in English as Toad lilies. Its native range is from the Himalayas to eastern Asia, including China, ref name china cite web work Flora of China url http efloras.org florataxon.aspx?flora id 2&taxon id 133597 title Tricyrtis Wallich ref Japan, ref Cite journal url http www.amjbot.org cgi content full 86 2 287 doi 10.2307 2656945 title The Effect of Geographic Range and Dichogamy on Genetic Variability and Population Genetic Structure in Tricyrtis Section Flavae Liliaceae year 1999 author Maki, Masayuki journal American Journal of Botany volume 86 pages 287 292 jstor 2656945 author2 Morita, Hiroko author3 Oiki, Syuji author4 Takahashi, Hiroshi issue 2 publisher Botanical Society of America postscript None pmid 21680367 ref Philippines and Formosa . ref name George2002 Cite book last George Schmid first W. year 2002 title An encyclopedia of shade perennials pages 312 url http books.google.com ?id oKVsZdgB QEC&pg RA1 PA312&dq Tricyrtis are native from isbn 0881925497 publisher Timber Press location Portland, Or. postscript None ref They are perennial herbaceous plant s that grow naturally at the edge of forests. They prefer shade or part shade and rich, moist soil. Toad Lilies bloom in the fall. They are hardy enough to handle sudden changes of winter from mild to blustery cold. ref Cox, Jeff 1998 by Rodale Press Perennial All Stars The 150 Best Perennials for Great Looking, Trouble Free Gardens, pg. 305 ref Species Species include Tricyrtis affinis small Tomitaro Makino Makino small Tricyrtis amethystina small Genkei Masamune Masam. small Tricyrtis ... more details
Environmental sex determination or ESD is any sex determination system in which sex is established by a nongenetic cue e.g. nutrient availability experienced within a discrete period after conception. In contrast, genotypic sex determination GSD occurs when sex is established by genetic factors e.g. sex chromosome s at conception. ref name janzen cite journal author F. J. Janzen & P. C. Phillips year 2006 title Exploring the evolution of environmental sex determination, especially in reptiles journal Journal of Evolutionary Biology volume 19 issue 6 pages 1775 1784 doi 10.1111 j.1420 9101.2006.01138.x pmid 17040374 url http www.public.iastate.edu fjanzen pdf 06JEB.pdf format Portable Document Format PDF ref Environmental sex determination should also not be confused with some forms of hermaphroditism in which the sex is determined flexibly after birth, such as dichogamy . Examples In the season in the amphipod Gammarus duebeni , photoperiod induces production of males earlier, and females later. Because male fitness improves more than female fitness with increased size, environmental sex determination is adaptive in this system by permitting males to experience a longer growing season than females. ref cite journal author J. McCabe & A. M. Dunn year 1997 title Adaptive significance of environmental sex determination in an amphipod journal Journal of Evolutionary Biology volume 10 issue 4 pages 515 527 doi 10.1046 j.1420 9101.1997.10040515.x ref The adaptive significance of environmental sex determination is not so clear for amniote s, however, the clade in which this it is perhaps most common. Most amniote vertebrates have genetic sex determination, but a small highly diverse set of taxa in this clade show environmental sex determination. In these latter animals, environmental sex determination occurs as temperature dependent sex determination TSD , wherein sex of individuals is permanently determined by thermal conditions experienced approximately during the middle ... more details
italictitle Taxobox name Calyptraea chinensis image Cuncha GFDL Galicia2.jpg image caption A group of gastropod shell shells of Calyptraea chinensis from Spain regnum Animal ia phylum Mollusca classis Gastropoda unranked superfamilia clade Caenogastropoda br clade Hypsogastropoda br clade Littorinimorpha superfamilia Calyptraeoidea familia Calyptraeidae subfamilia genus Calyptraea subgenus species C. chinensis binomial Calyptraea chinensis binomial authority Linnaeus, 1758 synonyms ref ref name WoRMS synonyms Calyptraea sinensis small Linnaeus, 1758 small Calyptraea chinensis , common name the Chinese hat snail or Chinese hat shell, is a species of small sea snail , a marine gastropod mollusk in the family biology family Calyptraeidae , the slipper snails or slipper limpets, cup and saucer snails, and Chinese hat snails. ref name WoRMS WRMS species 138961 Calyptraea chinensis Linnaeus, 1758 Gofas, S. 2009 . Calyptraea chinensis Linnaeus, 1758 . In Bouchet, P. Gofas, S. Rosenberg, G. 2009 World Marine Mollusca database. Accessed through the World Register of Marine Species at nowiki http www.marinespecies.org aphia.php?p taxdetails&i nowiki on 2010 06 03 ref ref Collins pocket guide, Sea Shore of Britain and Europe , HarperCollinsPublishers, London, 1996, ISBN 0 00 219955 6 ref Description The thin Gastropod shell shell of this species has the shape of an almost symmetrical cone like a Chinese hat or conical Asian hat , 7 mm high and 15 21 mm wide. The internal partition has a spirally curved edge which runs running from the Apex mollusc apex to the margin of the shell, and partly covers the Aperture mollusc aperture . The presence of this internal shelf distinguishes this species easily from the true limpet s. The aperture is round and adapted to the substrate. The shell is creamy white, and glossy on the inside. Calyptraea chinensis is a filter feeder , binding fine food particles with mucus . Like all slipper limpets, this species is a Dichogamy protandr ... more details
produce male and female flowers at different times to promote outcrossing. Dichogamy In flowering plants Dichogamy is common in flowering plants, and occurs when bisexual perfect flowers or sometimes ... more details
Shells of Crepidula fornicata common slipper shell . Sequential hermaphrodites dichogamy occur in species .... Dichogamy can have both conservation related implications for humans, as mentioned above, as well ... more details
Image Aleksandr Oparin and Andrei Kursanov in enzymology laboratory 1938.jpg thumb right 210px Biologists Aleksandr Oparin right and Andrei Kursanov left in the enzymology laboratory, 1938 This list of Russia n biologist s includes the famous biologists from the Russian Federation , the Soviet Union , the Russian Empire and other predecessor states of Russia. Biologists of all specialities may be listed here, including ecologist s, botanist s, zoologist s, paleontologist s, biochemist s, physiologist s and others. Expand list date February 2011 Alphabetical list compactTOC8 side yes seealso yes NOTOC A Johann Friedrich Adam , discoverer of the Adams mammoth , the first complete woolly mammoth skeleton Igor Akimushkin , notable biologist Vladimir Prokhorovich Amalitskii , notable paleontologist Nicolai Ivanovich Andrusov Nicolai Andrusov , notable palaeontologist Andrey Avinoff , notable entomologist B Karl Baer , naturalist, founder of the Russian Entomological Society , formulated embryological Baer s laws Alexander Barchenko , notable for his research of Hyperborea Jacques von Bedriaga , prominent herpetologist , described Bedriaga s Rock Lizard and Bedriaga s Skink Andrey Belozersky , founder of molecular biology Dmitry Konstantinovich Belyaev Dmitry Belyaev , domesticated silver fox Lev Berg , ichthyologist of Central Asia and European Russia Yuli Berkovich , experimented with seed germination in zero gravity Nikolai Bernstein , neurophysiologist, coined the term biomechanics Vladimir Betz , discovered giant pyramidal neurons of primary motor cortex Anatoli Petrovich Bogdanov , notable biologist Andrey Bolotov , major 18th century agriculturist , discovered dichogamy , pioneered cross pollination August von Bongard , botanist of Alaska , discoverer of Sitka Spruce and Red Alder Antonina Borissova , notable botanist Zinaida Botschantzeva , notable botanist Alexander Bunge , major botanist of Siberia especially Altai Mountains Altai File Andrei Bolotov.jpg thumb 9 ... more details
subgroup of the Labridae family Labrini do not exhibit broadcast spawning. homogamy versus dichogamyDichogamy, also known as sequential hermaphrodism, is the separation in time of gender expression ... points in their life cycle dichogamy . Homogamy is the maturation in hermaphroditic animals of the ova ... an organism changes sex during its lifetime. ref http www.wordnik.com words dichogamyDichogamy Wordnik ... more details
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