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Topic: Unisexual


In the News (Thu 24 Apr 14)

  
  Plant sexuality - Wikipedia, the free encyclopedia
Unisexual - Reproductive structure that is either functionally male or functionally female.
Monoecious - having unisexual reproductive units (flowers, conifer cones, or functionally equivalent structures) of both sexes appearing on the same plant; from Greek for "one household".
A fair degree of correlation (though far from complete) exists between dioecy/sub-dioecy and plants that have seeds dispersed by birds (both nuts and berries).
en.wikipedia.org /wiki/Plant_sexuality   (925 words)

  
 Preschool Flowers Fast Facts
However, in some species of plants the flowers are unisexual: having only either male (stamens) or female (pistil) parts.
In some of these species, an individual plant is either male or female and the species is regarded as dioecious; in others, the unisexual male and female flowers appear on the same plant and the species is termed monoecious.
Unisexual male and female flowers on the same plant may not appear at the same time, or pollen from the same plant may be incapable of fertilizing its ovules.
www.everythingpreschool.com /themes/flowers/encyclopedia.php   (762 words)

  
 Amphibian Articles - Hybrid Ambystomids
Diploid unisexual individuals possessing genomes from A. laterale and A. texanum are common in northwestern Ohio and southeastern Michigan (Petranka, 122).
Unisexuals produce unreduced ova that are stimulated to divide when a sperm of a diploid male penetrates the egg membrane.
Kraus, F. Unisexual salamander lineages in northwestern Ohio and southeastern Michigan: A study of the Consequences of Hybridization.
www.livingunderworld.org /amphibianArticles/article0015.shtml   (669 words)

  
 Forestry Glossary - Utah State University Forestry Extension
Monoecious: having unisexual flowers with staminate (male) and pistillate (female) flowers borne on the same tree, though often on different branches.
Polygamo-monoecious: having unisexual flowers with staminate (male) and pistillate (female) flowers borne on the same tree, along with some perfect flowers on each tree.
Unisexual flower: an imperfect flower; a flower with organs of only one sex present.
extension.usu.edu /forestry/UtahForests/Trees_BotanicalGlossary.htm   (1499 words)

  
 Sergey D. Grebelnyi. The mechanisms of unisexual reproduction and pure either maternal or paternal inheritance.
The unisexual reproduction occurs in quite different animal groups, though the all-female species are not numerous in nearly all the taxa.
At the same time in fishes, the unisexual forms are believed to be either gyno- or hybridogenetic, since in all the cases studied the successful development of eggs occurs only after their contact with sperm.
Berg, L.S. On the "unisexual" breeding in crucian carp.
www.zin.ru /annrep/2000/11.html   (2393 words)

  
 Weeds 1 No. 241
Unisexual flowers, male catkins are preformed in the summer and over winter, 1.5" to 2.5" long when mature in the spring; female catkins 0.5" long and slender.
Unisexual flowers; male catkin is 2"-4" long and female catkin is 0.5"-0.75" long.
Unisexual flowers borne in catkins on separate plants.
wildblueberries.maine.edu /FactSheets/241.htm   (487 words)

  
 Inflorescence Terminology (Part 1)
The small unisexual flowers are packed together along the lower region of an erect, phallus-like central spike, typically with male flowers above the female.
Catkin or Ament: A spike-like inflorescence of unisexual, apetalous flowers, often pendent and falling as a unit.
Spadix: A thick, fleshy spike of unisexual, apetalous flowers, often surrounded by a vase-shaped or funnel-like modified leaf or spathe which is often brightly colored.
waynesword.palomar.edu /terminf1.htm   (881 words)

  
 SEMINAR/STUDY TOUR IN THE U.S.S.R. ON GENETIC SELECTION AND HYBRIDIZATION OF CULTIVATED FISHES
Genetic data testifying to natural gynogenesis of the unisexual form of Crucian carp were obtained by the analysis of progeny of females of unisexual populations and males of other species.
Evidence of the genetic deficiency of such a male (from the unisexual population of the Yakot fishery of the Moscow region) was obtained by crossing it with a female C.
Females from the unisexual population of the Yakot fishery (the Moscow region) have proved to be triploid with ameiotic maturation.
www.fao.org /docrep/005/B3310E/B3310E20.htm   (7647 words)

  
 Niche relationships of clonal and sexual fish in a heterogenous landscape Ecology - Find Articles
The literature concerning unisexual vertebrates has expanded rapidly over the last few decades in response to the growing number of discoveries of unisexual taxa (Dawley 1989) and their usefulness in examining basic principles of ecology and evolutionary biology (Vrijenhoek 1994).
The first is that unisexuals are broadly adapted generalists, which may compete extensively with sexuals, but which possess adaptations that allow them to exploit a broad range of habitats and conditions that may serve as a refugium from intense competition.
Hence, according to the generalist model, unisexuals would be characterized as possessing a broad fundamental niche capable of exploiting a wide range of habitats and conditions, but competitive interactions would frequently confine their success to underutilized resources and areas to which their sexual hosts are poorly adapted.
www.findarticles.com /p/articles/mi_m2120/is_n3_v79/ai_20608566   (909 words)

  
 ANT 436, Primate Ecology & Social Behavior: Course Description 2003   (Site not responding. Last check: 2007-11-02)
Unisexual mole salamanders are composed of all female populations, which reproduce through mitosis.
Whereas most unisexual vertebrate lineages have been found to be relatively young, ranging from 10,000 to 50,000 years old, the unisexual lineage of Ambystoma are probably 2-5 million years old.
Occasionally, unisexual females require sperm from related sexual males to activate the development of their eggs, but the sperm does not contribute genetic material to the offspring.
www.chass.utoronto.ca /anthropology/ANT436/NSERC.html   (527 words)

  
 Malcomber, Simon T.*, Andrew N. Doust, Tony Verboom, and Elizabeth A. Kellogg.   (Site not responding. Last check: 2007-11-02)
Unisexual flowers have evolved multiple times within Poaceae in such diverse lineages as Bambusoideae, Ehrhartoideae, Pooideae, Danthonieae, Chloridoideae and Panicoideae.
The conversion from a bisexual to unisexual floral meristem in Zea mays is correlated with programmed cell death and the expression of tassleseed2 (ts2).
Little is known about the genetic basis of unisexual flowers in other grass lineages, although developmental studies in Zizania aquatica suggest that either ts2 is not involved in the production of male flowers or is regulated differently.
www.botany2001.org /section12/abstracts/187.shtml   (308 words)

  
 Re: Asexual reproduction in reptiles
The mechanism of reproduction among the unisexual species seems to involve production of haploid eggs by females (which is quite normal).
At least a couple of these unisexual species have been identified as hybrid offspring resulting from the mating of two other species of normal whiptails.
For example, the unisexual New Mexico whiptail (Cnemidophorus neomexicanus) appears to be the result of a crossbreeding of the western whiptail (C. tigris) and the little striped whiptail (C. inornatus).
www.madsci.org /posts/archives/dec96/844956732.Zo.r.html   (286 words)

  
 Malvaceae Info: Biology: Reproductive Biology: Distribution of Sexes
A flower may be either male, androus or staminate (with fertile stamens, but lacking fertile pistils), female, gynous, carpellate or pistillate (with fertile pistils but lacking fertile stamens), hermaphodite, bisexual, synoecious or perfect (with both fertile pistils and stamens) or sterile, neuter, neutral or agamous (with neither fertile pistils nor stamens).
Note: The plant life cycle incorporates an alternation of generations between the macroscopic diploid sporophyte and the microscopic haploid gametophytes, which in flowering plants are the embryo sac (female) and pollen grain (male).
The largest subgroup departing from this condition is subfamily Sterculioideae (12 genera, 400 species) in which the flowers are usually functionally unisexual, or polygamous [1].
www.malvaceae.info /Biology/SexDistribution.html   (1075 words)

  
 Plant Description
The small, unisexual flowers lack sepals and petals, and are arranged on erect to pendant catkins (aments).
Plants are dioecious, with unisexual male and female flowers borne on separate plants.
Flowers: Unisexual, male and female catkins (aments) on different shrubs (plants dioecious); catkins are borne on short leafy branches and appear with the leaves.
www.northernontarioflora.ca /description.cfm?speciesid=1004460   (348 words)

  
 Unisexual fish bibliography
Vrijenhoek, R. C., 1989 Genetic and ecological constraints on the origins and establishment of unisexual vertebrates, pp.
Wetherington, J. Kotora and R. Vrijenhoek, 1987 A test of the spontaneous heterosis hypothesis for unisexual vertebrates.
Vrijenhoek, R. Angus and R. Schultz, 1978 Variation and clonal structure in a unisexual fish.
www.mbari.org /~vrijen/unibib.htm   (990 words)

  
 Western Palearctic Water Frogs Abstracts   (Site not responding. Last check: 2007-11-02)
This suggests that there are strong genetic or cytological mechanisms in vertebrates that prevent unisexual reproduction, and that hybridization is needed to overcome them.
In one parental species (Rana ridibunda) of hybridogenetic frogs, there seems to be meiotic drive of the X chromosomes against the Y chromosome (and possibly the other chromosomes inherited from the sire), which appears to be suppressed.
Although all vertebrates require hybridization for unisexuality, this requirement appears not to be an ancestral state of the vertebrate clade.
evolution.genetics.washington.edu /PBhtmls/abstracts/sex_asex_repro.html   (465 words)

  
 Unisexual "Hybrid" Salamander Complexes, Ambystoma spp.
Unisexual salamanders can be diploid, triploid, tetraploid, or even pentaploid and may have "mixed" genotypes of the Blue-spotted Salamander, Small-mouth Salamander, Jeffson Salamander, and (less commonly) the Eastern Tiger Salamander.
Distribution in Ohio: Positively identified from the northern tier of counties along Lake Erie, unisexual salamanders may be present throughout the state.
Status in Ohio: Unisexual salamander complexes are the most common salamanders in many parts of northwestern Ohio.
www.ohioamphibians.com /salamanders/Unisexual_Ambystoma.html   (314 words)

  
 t.A.T.u., Tatu, Taty -- MP3s, Movies and News about this Russian Girl Band
Unisexual female love is getting really very popular in Russia.
Such demonstrations of unisexual love lasted for a rather long period until one of the girls, Angel, got tired of it and married.
Quite naturally that she married a man, one of those whom the group hated so much in the songs.
www.white-man-killer.com /tatu/tatu-news081202.html   (862 words)

  
 Plant Sexuality
Some plants have only unisexual flowers and are dioecious with separate male and female individuals in the population--like date palms, edible figs, willows, cottonwoods, marijuana and people.
Poison oak is essentially dioecious, but it may also be polygamous with bisexual and unisexual flowers on the same individual.
Figs are especially interesting because they have tiny unisexual male and female flowers inside a fleshy structure called a syconium.
waynesword.palomar.edu /ww0404.htm   (774 words)

  
 Floral development and the formation of unisexual spikelets in the Andropogoneae (Poaceae) -- Le Roux and Kellogg 86 ...
The formation of unisexual spikelets is also uniform.
maize is monoecious with unisexual florets borne on separate
maize, unisexual florets are borne in separate inflorescences.
www.amjbot.org /cgi/content/full/86/3/354   (4260 words)

  
 Flowering Plant Families, UH Botany
This is another example of the typical pseudanthium or cyathium found in the family.
It is characteristic for the single female flower in the center to become deflexed to one side as it matures.
This is an example of an ordinary inflorescence of unisexual flowers.
www.botany.hawaii.edu /faculty/carr/euphorbi.htm   (880 words)

  
 Urtica dioica in Flora of North America @ efloras.org
Flowers unisexual, staminate and pistillate on same or different plants, staminate ascending, the pistillate lax or recurved.
Plants unisexual, staminate and pistillate flowers on different plants; leaf blades abaxially hispid, both surfaces with stinging hairs.
Plants unisexual, staminate and pistillate flowers mostly on same plants; leaf blades abaxially bearing stinging hairs, otherwise glabrous, puberulent, or tomentose and moderately strigose, adaxially without (rarely with a few) stinging hairs.
www.efloras.org /florataxon.aspx?flora_id=1&taxon_id=220014002   (173 words)

  
 Flowering Plant Families, UH Botany
The leaves are alternate, commonly in 3 ranks, usually with a closed sheathing base and a parallel-veined, strap-shaped blade.
The flowers are very minute and are bisexual or unisexual.
Each floret is in the axil of a chaffy bract and these are arranged spirally or distichously in spikelets.
www.botany.hawaii.edu /faculty/carr/cyper.htm   (332 words)

  
 The evolution of unisexual flowers: morphological and functional convergence results from diverse developmental ...
The evolution of unisexual flowers: morphological and functional convergence results from diverse developmental transitions -- Mitchell and Diggle 92 (7): 1068 -- American Journal of Botany
The evolution of unisexual flowers: morphological and functional convergence results from diverse developmental transitions
Unisexual flower morphology was examined within a phylogenetic
www.amjbot.org /cgi/content/abstract/92/7/1068   (211 words)

  
 PACSOA - Palms of the South-West Pacific
Most are typically arecoid with tallish slender trunks usually terminating in a crownshaft and pinnate leaves and flowers being unisexual.
A lesser number are either coryphoid with palmate leaves, always lacking crownshafts and having bisexual flowers, or calamoids, being scaley fruited rattans with unisexual flowers or massive monocarpic palms with terminal infloresences, also with fruits.
The majority of the palms are endemic to small islands; a few species may be considered very rare, being known from only small populations with limited distribution.
www.pacsoa.org.au /books/reviews/PalmsSWPacific.html   (442 words)

  
 Special Words for Dealing with Flowers
ament: a catkin, which is a scaly-bracted, usually drooping spike or spike-like raceme with unisexual flowers; typical of willows and poplars
catkin: a scaly-bracted, usually drooping spike or spike-like raceme with unisexual flowers; typical of willows and poplars
monoecious: staminate (male) and pistillate (female) flowers on the same plant, as in corn (as opposed to dioecious, in which unisexual flowers occur on the separate plants)
www.backyardnature.net /fl_words.htm   (1061 words)

  
 conclude
inflorescence cyathium, unisexual flower, ovary 3 locules 3 carpels, carunculate micropyle
milky latex, inflorescence cyathium, unisexual flower, ovary 3 locules 3 carpels, carunculate micropyle
unisexual flower, sympetalous flower, superior ovary, fruit berry
www.pharm.chula.ac.th /vichien/concl43/concl.htm   (646 words)

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