Floral development of Zannichellia palustris

1976 ◽  
Vol 54 (8) ◽  
pp. 651-662 ◽  
Author(s):  
U. Posluszny ◽  
R. Sattler
Keyword(s):  
Floral Development ◽  
Staminate Flower ◽  
Pistillate Flower ◽  
Bisexual Flower ◽  
The Third ◽  
Short Style ◽  
Procambial Strand ◽  
The One ◽  
The Right ◽  
Floral Bud

What, at maturity, appears to be a bisexual flower in the axil of one of two subopposite leaves, is revealed as a fertile nodal complex with quite different organization. Three appendages develop at each nodal complex. The first girdles the stem and becomes at maturity a membranous sheath about the entire node. The second subtends the axillary meristem, which terminates as the staminate flower, and branches laterally as a renewal growth in the axil of a sterile appendage just below the stamen. The third appendage is subopposite the terminal meristem, which gives rise to the pistillate floral bud towards the staminate flower, and a renewal growth apex towards the appendage. This renewal growth apex repeats the entire pattern at almost a 90° shift to the right or left, depending on the shoot. The single stamen of the staminate flower develops as those studied in Potamogeton and Ruppia. The pistillate flower develops two carpel primordia, which become peltate before initiating a single ovule primordium on the adaxial portion (Querzone). The membranous envelope which covers the carpels at maturity is initiated at ovule inception, below one of the carpels. A peltate stigma differentiates on a short style and at maturity becomes broad and lobed. The renewal growth apex has a one-layered tunica. The membranous sheaths of the node and of the pistillate flower are primarily protodermal in origin, while the rest of the sterile and reproductive appendages arise through activity in subprotodermal cells. Procambial development is acropetal closely following primordial inception. Each organ (sterile or fertile) receives one procambial strand, except for the membranous sheath about the node and the one about the pistillate flower.

Floral development of Najas flexilis

1976 ◽  
Vol 54 (10) ◽  
pp. 1140-1151 ◽  
Author(s):  
U. Posluszny ◽  
R. Sattler
Keyword(s):  
Floral Development ◽  
Staminate Flower ◽  
Pistillate Flower ◽  
Axillary Meristem ◽  
Short Style ◽  
Najas Flexilis ◽  
Floral Apex ◽  
Cell Layers ◽  
The One ◽  
Floral Bud

Two subopposite leaves form at a node. The lower one arises almost simultaneously with the axillary meristem which it subtends. The upper leaf initiates after the lower one and does not subtend any structure. The axillary meristem gives rise to a renewal growth apex and a floral bud almost at its inception. In some cases the axillary meristem forms only a floral bud. The floral bud may be either staminate or pistillate. The main axis and the renewal growth in the axil of the lower leaf repeat this pattern of development. Staminate and pistillate flowers are almost indistinguishable at inception. They form as dome-like protuberances and both initiate girdling primordia, which become lobed at or immediately after inception. In the staminate flower the girdling primordium becomes the outer envelope, while a second girdling primordium formed acropetally becomes the inner envelope. Both envelopes overgrow the one-celled anther, which is the transformed staminate floral apex. In the pistillate flower the girdling primordium becomes the gynoecial wall that encloses the single bitegmic ovule, which is the transformed pistillate floral apex. On a short style a stigma with two to four branches develops. The renewal growth apices have a one-layered tunica. The two subopposite leaves are initiated through cell division in both tunica and corpus cells. The axillary meristem arises through periclinal divisions in the corpus cells. The girdling primordia of both staminate and pistillate floral buds are epidermal in origin as are the integuments of the ovule. Procambial development is acropetal following closely primordia inception. Each leaf, floral bud, and renewal growth apex receives a single strand. No vascularization is seen in envelopes of the staminate flower or the gynoecial wall of the pistillate flower, all of which remain two cell layers thick even at maturity.

scholarly journals Ethylene and 1-methylcyclopropene action over senescence of nasturtium flowers

2015 ◽  
Vol 33 (4) ◽  
pp. 453-458 ◽  
Author(s):  
Tania P Silva ◽  
Fernando L Finger
Keyword(s):  
Floral Development ◽  
Development Stage ◽  
Flower Senescence ◽  
Premature Senescence ◽  
Flower Opening ◽  
Development Stages ◽  
Post Harvest ◽  
The Third ◽  
Exogenous Ethylene ◽  
Floral Bud

ABSTRACT: This work describes ethylene and 1-methylcyclopropene (1-MCP) action on post-harvest shelf life of four development stages of nasturtium flowers. To reach this goal, we carried out three experiments. In the first and second experiments, we studied five ethylene (0; 0.1; 1; 10; 100 and 1000 μL/L) and three 1-MCP concentrations (0.25; 0.5 and 0.75 μL/L), respectively. In the third experiment, 1-MCP was followed by combined with ethylene (only 1-MCP; only ethylene; and 24 hours of exposure to 0.75 μL/L 1-MCP followed by 24 hours of exposure to 100 μL/L ethylene). All experiments had two control treatments, one keeping non-exposed flowers inside and another outside exposure chambers. Experiments were set in factorial design, in complete blocks at random, with four 10-flower replications each. Flower senescence was determined by a pre-established visual scale and by observing floral bud development. Ethylene dose above 10 μL/L induced flower wilting and premature senescence from the second floral development stage. Furthermore, higher concentrations of exogenous ethylene promoted irregular flower opening and/or morphological abnormalities in opened flowers. 1-MCP effectively extended post-harvest longevity of nasturtium flowers, independent of the concentration and even in the presence of exogenous ethylene.

Floral development of Potamogeton densus

1973 ◽  
Vol 51 (3) ◽  
pp. 647-656 ◽  
Author(s):  
U. Posluszny ◽  
R. Sattler
Keyword(s):  
Floral Development ◽  
The Other ◽  
Floral Meristem ◽  
Developmental Sequence ◽  
Initial Activity ◽  
The Third ◽  
Stamen Primordia ◽  
Procambial Strand ◽  
Inflorescence Axis ◽  
Rates Of Growth

The floral appendages of Potamogeton densus are initiated in an acropetal sequence. The first primordia to be seen externally are those of the lateral tepals, though sectioning young floral buds (longitudinally, parallel to the inflorescence axis) reveals initial activity in the region of the lower median (abaxial) tepal and stamen at a time when the floral meristem is not yet clearly demarcated. The lateral (transversal) stamens are initiated simultaneously and unlike the median stamens each arises as two separate primordia. The upper median (adaxial) tepal and stamen develop late in relation to the other floral appendages, and in some specimens are completely absent. Rates of growth of the primordia vary greatly. Though the lower median tepal and stamen are initiated first, they grow slowly up to gynoecial inception, while the upper median tepal appears late in the developmental sequence but grows rapidly, soon overtaking the other tepal primordia. The four gynoecial primordia arise almost simultaneously, although variation in their sequence of inception occurs. The two-layered tunica of the floral apices gives rise to all floral appendages through periclinal divisions in the second layer. The third layer (corpus) is involved as well in the initiation of the stamen primordia. Procambial strands develop acropetally, lagging behind primordial initiation. The lateral stamens though initiating as two primordia each form a single, central procambial strand, which differentiates after growth between the two primordia of the thecae has occurred. A great amount of deviation from the normal tetramerous flower is found, including completely trimerous flowers, trimerous gynoecia with tetramerous perianth and androecium, and organs differentiating partially as tepals and partially as stamens.

Origins

2018 ◽  
Author(s):  
Peter Mitchell
Keyword(s):  
Short Distance ◽  
Cervical Vertebra ◽  
Genetic Studies ◽  
Human Interactions ◽  
The Third ◽  
Wild Ass ◽  
History Of ◽  
Kill Site ◽  
The One ◽  
The Right

Over 50,000 years ago a Neanderthal hunter approached a wild ass on the plains of northeastern Syria. Taking aim from the right as the animal nervously assessed the threat, he launched his stone-tipped spear into its neck, penetrating the third cervical vertebra and paralyzing it immediately. Butchered at the kill site, this bone and most of the rest of the animal were taken back to the hunter’s camp at Umm el Tlel, a short distance away. Closely modelled on archaeological observations of that vertebra and the Levallois stone point still embedded within it, this incident helps define the framework for this chapter. At the start of the period it covers, human interactions with the donkey’s ancestors were purely a matter of hunting wild prey, but by its end the donkey had been transformed into a domesticated animal. Chapter 2 thus looks at how this process came about, where it did so, and what the evolutionary history of the donkey’s forebears had been until that point. Donkeys and the wild asses that are their closest relatives form part of the equid family to which zebras and horses also belong. Collectively, equids, like rhinoceroses and tapirs, fall within the Perissodactyla, the odd-toed division of hoofed mammals or ungulates. Though this might suggest a close connection with the much larger order known as the Artiodactyla, the even-toed antelopes (including deer, cattle, sheep, and goats), their superficial resemblances may actually reflect evolutionary convergence; some genetic studies hint that perissodactyls are more closely related to carnivores. Like tapirs and rhinoceroses, the earliest equids had three toes, not the one that has characterized them for the past 40 million years. That single toe, the third, now bears all their weight in the form of a single, enlarged hoof with the adjacent toes reduced to mere splints. This switch, and the associated elongation of the third (or central) metapodial linking the toe to the wrist or ankle, is one of the key evolutionary transformations through which equids have passed. A second involves diet since the earliest perissodactyls were all browsers, not grazers like the equids of today.

WU, MIN AND A LITTLE HAKKA LEXICAL TONE SANDHI: RIGHT AND LEFT

1984 ◽  
Vol 13 (1) ◽  
pp. 3-34
Author(s):  
William L. Ballard
Keyword(s):  
Pitch Accent ◽  
Lexical Tone ◽  
Tone Sandhi ◽  
The Third ◽  
Separate Type ◽  
Southern Min ◽  
The One ◽  
The Right

An initial assay of Wu and Min lexical tone sandhi opens inquiry into a possible source : Austronesian pitch accent, and into a sandhi origin for the "third" tone ( qu/departing ). One important element in such an assay is the feature Right/Left : focus = preservation, stress, retention, etc, towards the Right or towards the Left. Northern Wu appears to be focus Left, and destressing seems to be spreading in the area. Southern Wu and Min are focus Right. Southern Wu focus does not prevent some Right mergers, and often it is the last two syllables acting together that is the focus. Northern Min shows similarities to Southern Wu, but Southern Min can be said to have no tone sandhi at all : The Amoy et al tone circles appear to be artifacts of changes in isolation values, since they are virtual reconstructions of the probable prototone values. The one Hakka dialect examined appears to be like Northern Min/Southern Wu. On the basis of this assay, I would hazard the guess that in the study of the origin of lexical tone sandhi, Southern Min should be classified with the Cantonese/Thai type, Northern Wu as a separate type heavily influenced by Mandarin, and Southern Wu/Northern Min as the preservation of the oldest, most Austronesianoid type of sandhi. Further speculation would be foolhardly until more information is available and more detailed comparisons and histories are drawn up.

Floral development of Aponogeton natans and A. undulatus

1977 ◽  
Vol 55 (9) ◽  
pp. 1106-1120 ◽  
Author(s):  
V. Singh ◽  
R. Sattler
Keyword(s):  
Cell Division ◽  
Developmental Stage ◽  
Floral Development ◽  
Developmental Stages ◽  
Point Of View ◽  
Stages Of Development ◽  
The Third ◽  
Procambial Strand ◽  
Tunica Layer

The primordia of the floral appendages are initiated in an acropetal succession. Members of the same whorl appear nearly simultaneously. The gynoecial whorl and the two staminal whorls are trimerous, whereas the perianth consists only of two anteriolateral tepals. However, the posterior (adaxial) tepal may be present as an extremely reduced buttress whose growth becomes arrested immediately after its inception. If this somewhat questionable tepal rudiment is included we have a perfectly trimerous and tetracyclic flower with alternation of successive whorls. Subtending bracts of the flowers are completely missing in all developmental stages. While the tepal primordia are dorsiventral from their inception, the stamen and pistil (carpel) primordia originate as hemispherical mounds which become dorsiventral in subsequent stages of development. Each pistil (carpel) primordium becomes horseshoe shaped. As the margins grow up and contact they fuse postgenitally. No cross zone is formed. Placentation is submarginal. In A. natans eight ovules are formed and in A. undulatus only two arise; all ovules are bitegmic. The floral apices have a two-layered tunica up to the stage of pistil formation. The inception of all floral appendages (including the ovules) occurs by periclinal cell division in the second tunica layer. The third layer (corpus) may contribute to the formation of the stamens and pistils. Each appendage primordium receives only one procambial strand which begins to differentiate after the inception of the primordium. The questionable rudimentary tepal buttress lacks a procambial strand. Apparently it does not reach the developmental stage at which procambial induction occurs. From the point of view of floral development, the two species of Aponogeton differ drastically from members of the Alismatales studied so far. Among the Helobiae, the Aponogetonaceae appear to be most closely related to the Scheuchzeriaceae and the Juncaginaceae (Triglochinaceae).

Floral development of Ruppia maritima var. maritima

1974 ◽  
Vol 52 (7) ◽  
pp. 1607-1612 ◽  
Author(s):  
U. Posluszny ◽  
R. Sattler
Keyword(s):  
Floral Development ◽  
Early Ontogeny ◽  
Main Axis ◽  
Ruppia Maritima ◽  
Procambial Strand ◽  
Inflorescence Axis ◽  
Floral Apex ◽  
Median Position ◽  
Floral Bud

A hyaline, unvascularized sheath envelops a portion of the inflorescence near maturity. Though resembling an appendage of the main axis, in early ontogeny it develops as a prophyll of the renewal growth apex below the inflorescence. Two flowers develop on the inflorescence axis, subopposite each other. Fertile appendages are initiated in an acropetal sequence on each floral bud. The first to form, in the median position, are the two stamens, the lower preceding the upper. Each stamen develops two bisporangiate thecae separated by a broad connective. A dorsiventral outgrowth is initiated slightly abaxially near the tip of the connective at the stage of theca differentiation. This outgrowth appears to be homologous with a similar outgrowth in Potamogeton densus, but not with the sterile appendages of the Potamogeton flower which, by some authors, have incorrectly been interpreted as connective outgrowths. Each carpel arises as a radial primordium which becomes peltate after its inception. One ovule is initiated at the adaxial portion (Querzone). The stigma becomes broad and flat, lobing at its margins. A slight outgrowth develops at the abaxial wall of the carpel. The floral apex has a two-layered tunica. The primordia of the stamens, carpels, and ovules arise by periclinal divisions in the second layer. Procambial development is acropetal following closely primordial inception. Each appendage, including the ovule, receives one procambial strand. The outgrowths of the connective and the carpel lack procambium.

Prospects for Future World Communication

1989 ◽  
Vol 2 (1) ◽  
pp. 64-77
Author(s):  
Henk Hartog
Keyword(s):  
Third World ◽  
Freedom Of Information ◽  
International Flow ◽  
The Third ◽  
Right To Communicate ◽  
Third World Development ◽  
The One ◽  
The Right ◽  
The Third World ◽  
Flow Of Information

The international flow of information produced by international press agencies is discussed in this article. The author shows how the position of the Third World with respect to the alleged imbalances in the international communication infrastructure, both quantitative and qualitative, has led to two legal developments. On the one hand, the ‘right to communicate’ was formulated in addition to the traditionally recognized freedom of information. On the other hand, the concept of a New World Information Order has been developed. The ideological battle between the West and the Third World, which has dominated the discussion on these concepts since the early 1970s, should, according to the author, not impair the development of a viable technological infrastucture in the Third World. Development assistance could be used to give new and independent news agencies access to the international flow of information.

scholarly journals Youth and the third sector media in Spain: Communication and social change training

Comunicar ◽  
2016 ◽  
Vol 24 (48) ◽  
pp. 91-99 ◽  
Author(s):  
Isabel Lema-Blanco ◽  
Eduardo-Francisco Rodríguez-Gómez ◽  
Alejandro Barranquero-Carretero
Keyword(s):  
Media Literacy ◽  
Citizen Participation ◽  
Research Method ◽  
Third Sector ◽  
The Third ◽  
Qualitative Focus Groups ◽  
The Third Sector ◽  
The One ◽  
The Right

The aim of this paper is to examine the role of community, free and university media in Spain as tools for media literacy and as instruments for creating a more critical and communicative citizenry. After a conceptual section, we analyse training processes in this area with regard to the general population and their reference communities, devoting particular emphasis to the involvement of young people. The triangulation research method was based on quantitative (a survey) and qualitative (focus groups) techniques. The results show that the third sector media in Spain act as invaluable tools for the acquisition of skills and competences that are transferable into young people’s professional and experiential sphere, given the ability of these media outlets to identify with their interests, aspirations and difficulties. In a broad sense, these initiatives contribute to expanding the right of communication in two different ways: on the one hand, because they are open to citizen participation in both management responsibilities and content programming; and, on the other, because their decentralized practices provide a laboratory for creative journalism which, in turn, is linked to social movements and other means of expression for citizens (NGOs, associations, etc.). El siguiente trabajo tiene por objeto acercarse al papel de los medios comunitarios, libres y universitarios del Estado español como instrumentos para la alfabetización mediática y en tanto que espacios para la conformación de ciudadanía crítica y comunicativa. Tras el apartado conceptual, se analizan los procesos de aprendizaje que se implementan con respecto a la ciudadanía en general y a las comunidades de referencia en particular, prestando especial atención al rol y a la participación de la juventud. A partir de la triangulación de técnicas cuantitativas (encuesta) y cualitativas (grupos de discusión), los resultados demuestran que los medios del tercer sector actúan como valiosas herramientas para la adquisición de habilidades y competencias críticas que pueden transferirse a la esfera profesional y vivencial de los jóvenes, dada la identificación de estos medios con los intereses, problemáticas y aspiraciones juveniles. En un sentido amplio, estas iniciativas contribuyen a la expansión del derecho a la comunicación en dos irecciones: por un lado, porque están abiertas a la participación ciudadana en las tareas de gestión y programación de los contenidos; y, por otro, porque sus prácticas descentralizadas constituyen un laboratorio de creatividad periodística que, a su vez, está vinculado al devenir de los movimientos sociales y otras formaciones de la ciudadanía organizada (ONG, asociaciones, etc.).

The Sunghir Dental and Alveolar Remains

2014 ◽  
Author(s):  
Erik Trinkaus ◽  
Alexandra P. Buzhilova ◽  
Maria B. Mednikova ◽  
Maria V. Dobrovolskaya
Keyword(s):  
Small Area ◽  
Alveolar Bone ◽  
Third Molars ◽  
The Third ◽  
Mandibular Teeth ◽  
The Times ◽  
The One ◽  
The Right ◽  
Crown Dimensions ◽  
Missing Tooth

Sunghir 1, 2, and 3 retain most of their maxillary and mandibular teeth, although those of Sunghir 1 are heavily worn and those of Sunghir 2 and especially Sunghir 3 were developing at the times of their deaths. As a result, the two immature individuals provide extensive data on their dental crown discrete morphology and crown metrics, but there are limited data on the third molars of Sunghir 2 and on the premolars and second molars of Sunghir 3 (and none on her third molars beyond their calcification stage; see chapter 6). In addition, although they retain none of their teeth, Sunghir 5 and especially 6 preserve alveolar bone, and they thereby provide limited dentoalveolar data. The Sunghir dentitions and alveoli thus have the potential to provide paleobiological data on their crown configurations, crown dimensions, some root lengths and configurations, in addition to wear patterns. The condition and salient aspects of each are provided first, followed by comparisons of their dimensions and shapes in a Late Pleistocene context. As noted in chapter 4, Sunghir 1 retains 31 of his original 32 teeth, and the one missing tooth, the left I2, was probably lost shortly before death. All of the teeth are heavily worn, thereby limiting morphological and morphometric observations principally to the M3s. But the other teeth provide considerable information regarding their wear patterns. The right I1 consists of worn dentin with a partial thin enamel ring around the labial margin of the crown. The dentin is occlusally flat to convex, the convexity produced mostly by a rounding of the lingual edge of the crown. There is a small area of secondary dentin exposed in the middle of the occlusal dentin. Note that the protruding nature of the tooth is a postmortem artifact, and it probably was originally at the same level as the left I1. There is no unusual wear in the mandibular incisors to match its procumbent state. The left I1 has similar wear, except that it retains more of the thin enamel ring around the lingual side and hence lacks the lingual rounding evident on the right one.

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