scholarly journals The riddle of phyllotaxis: exquisite control of divergence angle

2016 ◽  
Vol 85 (4) ◽  
Author(s):  
Takuya Okabe
Keyword(s):  
Plant Species ◽  
Shoot Apex ◽  
Evidence Base ◽  
Divergence Angle ◽  
Shoot Apices ◽  
Essential Point

Phyllotaxis studies published in German in the 1930s have reported intriguing regularity in the arrangement of incipient leaves on shoot apices of a wide variety of plant species. However, these studies have received little attention today, even though they provide a crucial evidence base for understanding this mathematical phenomena. Here I recapitulate the essential point by means of illustrative examples. It is emphasized that accurate control of apical divergence angle is at the heart of the numerical riddle of spiral phyllotaxis. The accurate patterning at the shoot apex has an unexpected evolutionary benefit of being optimally adaptive in the subsequent events of phyllotactic change to occur on an elongating shoot.

HISTOCHEMICAL CHANGES IN THE SHOOT TIP OF CAULIFLOWER DURING FLORAL INDUCTION

1967 ◽  
Vol 45 (7) ◽  
pp. 955-959 ◽  
Author(s):  
Sidki Sadik ◽  
J. L. Ozbun
Keyword(s):  
Shoot Apex ◽  
Dna Content ◽  
Deoxyribonucleic Acid ◽  
Floral Induction ◽  
Fold Increase ◽  
Bromophenol Blue ◽  
Shoot Apices ◽  
Fast Green ◽  
Floral Primordia ◽  
Histochemical Changes

Cauliflower plants were induced to flower after being grown at 42 °F for varying periods of time, depending on the cultivar. Some of the histochemical changes in the shoot apex at the beginning of, during, and after floral induction were studied. During floral induction there is about a 20-fold increase in the volume of nucleoli and about a 3-fold increase in volume of nuclei. Apices of vegetative plants stained with bromophenol blue at pH 2.3, show small and dense nucleoli, dense and granular nuclei, and a small amount of weakly staining cytoplasm. In contrast, cells of apices of induced plants stained with bromophenol blue at pH 2.3, show large and dense nucleoli, large and weakly staining nuclei; however, these cells contain more and denser cytoplasm. Sections of vegetative and induced apices stained with alkaline fast green stained differently from those stained with bromophenol blue. Nucleoli did not stain and cytoplasm stained faintly with fast green while chromosomes stained strongly. Deoxyribonucleic acid (DNA) content of vegetative and induced apices are similar. Shoot apices of vegetative plants contained little or no starch. However, shoot apices of plants grown at 42 °F accumulate large amounts of starch. Floral primordia which develop into functional flowers are glutted with starch, while floral primordia which abort are void of starch.

scholarly journals ISOLATE TWO SPECIES OF COMPOSITAE FAMILY E.armatus BOISS&HAUSSKN AND E.cephalotes DC. BY MORPHOLOGICAL AND VEGETATIVE SHOOT APEX FOR THE FIRST TIME IN IRAQ

2017 ◽  
Vol 48 (5) ◽  
Author(s):  
Al-Musawi & et al.
Keyword(s):  
Plant Species ◽  
Shoot Apex ◽  
Pollen Grains ◽  
Reproductive Organs ◽  
The Other ◽  
Vegetative Shoot ◽  
Northern Areas ◽  
Vegetative Shoot Apex ◽  
Perennial Herbs ◽  
First Time

Present study delts with morphological and vegetative shoot apex characteristics of two species  Echinops armatus and E.cephalotes (compositae) which collected during trips field to the northern areas of Iraq in the seasons of growth 2012-2014. As it presents the results and characters  had been shown for the first time in Iraq. plant species are perennial herbs spinous with woody, strong and solid stems that covered with many types of indumentums like spines and hairs, the study included characters of stems, leaves, involucres bracts and inflorescences as well as characters of growing points of the two species, and by examining buds in inflorescences found that the flowers are hermaphrodite, not sterile which containing all the reproductive organs like stamens, pollen grains, pistils and ovaries, an early dehesence as mature anthers and bloom before the maturation of pistils and disperse their pollen.The study also discussed variations within the characters and it became clear that the characters of leaves, stems and involucres especially inner cycle, including the importance of taxonomic great isolate the two species. Ranged prepare involucres braces  in the first species is (20-23) bracts while the number varied between (19-20) bracts in the other one. The study showed the importance of growing points  in isolating the two species where characterized by two meristematic area in longitudinal embryos species. The first spices recognized by two rows of cells, while the other one marked three rows or layers of components of Tunica cells area, and ensures find accurate measurements of parts phenotypic as well as illustrations of morphological and anatomical parts studied.                   

scholarly journals The unified rule of phyllotaxis explaining both spiral and non-spiral arrangements

2019 ◽  
Vol 16 (151) ◽  
pp. 20180850 ◽  
Author(s):  
Takuya Okabe ◽  
Atsushi Ishida ◽  
Jin Yoshimura
Keyword(s):  
Shoot Apex ◽  
Stem Growth ◽  
Divergence Angle ◽  
Simple Fraction ◽  
Morphological Convergence ◽  
Golden Angle ◽  
Plant Groups

Leaf-like appendages of different plant groups are arranged in common phyllotaxis patterns categorized into two types: spiral and non-spiral arrangements. The adaptive reason for this morphological convergence is unknown. In the non-spiral arrangement, the divergence angle between successive leaves is a simple fraction of 360°, e.g. distichy, decussate and whorled phyllotaxis. In the spiral arrangement, the divergence angle of nascent leaves at the shoot apex is fixed at the golden angle 137.5°, whereas those of the developed leaves varies within a sequence of Fibonacci fractions, such as 1/3, 2/5, 3/8, 5/13, etc. The optimality of the golden angle has been shown recently by assuming that the pattern of developed leaves varies during growth in a manner depending on the divergence angle of nascent leaves. Here we propose a unified rule of phyllotaxis to explain both types of arrangement: the developed leaves form vertical rows along the stem. In the non-spiral arrangement, nascent to developed leaves always follow this rule, so that the number of leaf rows is kept constant irrespective of stem growth. In the spiral arrangement, developed leaves attain this rule by adjusting the divergence angle from the golden angle. The spiral arrangement is adaptive in that the number of leaf rows varies during growth depending on shoot thickness.

The genesis of form in flax and lupin as shown by scale drawings of the shoot apex

1970 ◽  
Vol 18 (2) ◽  
pp. 167 ◽  
Author(s):  
RF Williams
Keyword(s):  
Shoot Apex ◽  
Serial Sections ◽  
Shoot Apices ◽  
Potential Value

Procedures for the preparation of perspective drawings from serial sections of shoot apices and similar small structures are described, and the properties of the projection are critically examined. The procedures have potential value for morphogenetic studies, and examples are given for shoot apices of flax and lupin. For lupin it is shown that the folioles arise in an oblique circle at the top of the emerging petiole. After the median member, they appear in pairs at unit plastochron intervals.

Etude de la teneur en DNA nucléaire dans le méristème apical des tiges du Celosia cristata (Amarantacées) en fonction de la photopériode

1979 ◽  
Vol 57 (24) ◽  
pp. 2760-2765 ◽  
Author(s):  
D. Driss-Ecole
Keyword(s):  
Shoot Apex ◽  
Nuclear Dna ◽  
Intermediate Phase ◽  
Central Zone ◽  
Shoot Apices ◽  
Two Samples ◽  
Dna Values ◽  
Celosia Cristata ◽  
Zone Characteristic ◽  
Cytophotometric Study

Two samples of plants of Celosia cristata, a quantitative short-day plant, were grown in an 8-h or a 16-h day. The shoot apices were collected at 11, 15, 18, and 28 days in order to carry out a cytophotometric study of the nuclear DNA in the corpus. This distribution of the DNA values was analyzed statistically using the χ2 test. At the beginning of development, for both 8-h day and 16-h day plants, the DNA content of the majority of the nuclei is at the 2C level. Then the percentage 2C–4C or 4C nuclei increases, slowly for the plants grown under a 16-h photoperiod and quickly for the others. At the 28th day, the Gaussian distribution of DNA values indicates that the state reached by the meristems is quite different. Between the 18th day and the 28th day of culture, ontogenesis of the shoot apex goes through a critical period. At the end of this period, shoot apices of the plants grown under a 16-h photoperiod are in the intermediate phase with a majority of nuclei in the synthetic phase (S) or in the postsynthetic phase (G2). Simultaneously, structural modifications of the axial zone give rise to a central zone characteristic of the fasciation of the shoot apex. In plants grown with an 8-h photoperiod, the shoot apex goes through the prefloral phase with more numerous nuclei in the presynthetic phase (G1) or in the synthetic one (S). For each sample the nuclei clustered in a particular phase of the cell cycle indicate that a certain synchronism of the cell cycles in the corpus takes place. These results are compared with those recently obtained by other authors working with different plants.

MICROPROPAGATION OF Helianthus maximiliani (Schrader) BY SHOOT APEX CULTURE / MICROPROPAGACION DE Helianthus maximiliani (Schrader) POR EL CULTIVO DE VAINAS DE LOS VASTAGOS / MICROPROPAGATION DE L’Helianthus maximiliani (Schrader) AU MOYEN DE LA CULTURE DE L’APEX DE LA POUSSE

Helia ◽  
2001 ◽  
Vol 24 (34) ◽  
pp. 63-68 ◽  
Author(s):  
Vasić Dragana ◽  
Škorić Dragan ◽  
Alibert Gilbert ◽  
Miklič Vladimir
Keyword(s):  
Silver Nitrate ◽  
Shoot Apex ◽  
Casein Hydrolysate ◽  
Shoot Tips ◽  
Nodal Segments ◽  
Shoot Apices ◽  
Skoog Medium ◽  
Leaf Mesophyll ◽  
Murashige And Skoog Medium

SUMMARYH.maximiliani was micropropagated using culture of shoot apices on modified Murashige and Skoog medium (DV). Further propagation of in vitro grown plants was done by culture of their nodal segments and shoot tips on the same medium supplemented with phloridzin, silver nitrate and casein hydrolysate (DV'). Rooting was induced by dipping the explants into IBA solution prior culture. Viable protoplasts (90%) were isolated from leaf mesophyll. These protoplasts divided (18%) in culture in agarose droplets.

In vitro morphogenesis in Osmunda cinnamomea. The role of the shoot apex in early leaf development

1969 ◽  
Vol 47 (4) ◽  
pp. 575-580 ◽  
Author(s):  
G. S. Hicks ◽  
T. A. Steeves
Keyword(s):  
Shoot Apex ◽  
Leaf Development ◽  
Leaf Primordia ◽  
Shoot Apices ◽  
In Vitro Morphogenesis ◽  
Indeterminate Growth ◽  
Nutrient Culture ◽  
Determinate Growth

In sterile nutrient culture, shoot apices of the rhizome of Osmunda cinnamomea L., devoid of all visible foliar primordia, quickly give rise to dorsiventral leaf primordia at a presumptive leaf site (I1). It was established that these primordia were irreversibly determined as leaves. To examine the morphogenetic role of the shoot apex in governing early leaf development, this site was permanently isolated from the shoot apex by a single tangential cut. Usually, radially symmetrical shoots of indeterminate growth arose at I1 as a result of this surgery. By contrast, when organic continuity between I1 and the shoot apex was only temporarily interrupted by a cut which was subsequently allowed to heal, normally oriented dorsiventral leaf primordia formed most frequently at I1. These, too, were determined as leaves. It was concluded that the shoot apex serves as a source of determinative influences for the nascent primordium, imposing dorsiventrality and a pattern of determinate growth on the leaf site.

scholarly journals Two algorithms of determining the middle point of the shoot apex by surrounding organ primordia positions and their usage for computer measurements of divergence angles

2014 ◽  
Vol 67 (2) ◽  
pp. 151-159 ◽  
Author(s):  
Adam Matkowski ◽  
Radosław Karwowski ◽  
Beata Zagórska-Marek
Keyword(s):  
Shoot Apex ◽  
Computer Application ◽  
Divergence Angle ◽  
Middle Point ◽  
Coniferous Trees ◽  
Apical Dome ◽  
Age Profile ◽  
Program Version

The measurements of the divergence angle between organ primordia in magnolia floral apices and vegetative apices (embryonic shoots) of coniferous trees were performed, using computer application Phyl for IRIX. It appears that the values of the angle are strongly affected by the position of the apex centre, which was calculated by the program on a base of input positions of surrounding primordia. Two algorithms were used to determine the centre position: in program version Phyl 1 it was calculated as the gravity centre whereas in Phyl 2 version as a geometrical midpoint. The both methods differ in resulting centre position. This is dependent on such apex features as: proportions between its size and the size of primordia (expression of phyllotaxis), the angular distances between succesive primordia (quality of phyllotaxis), radial distances between primordia of different age (profile of the apical dome), the number of recorded primordia. The accuracy and reliability of both algorithms for determination of the centre position and, consequently, the reliability of divergence measurements were verified by applying them to ideal, computer simulated spiral phyllotactic systems with divergence given arbitrarily by the user. The conclusions from the results of simulations are that there is a possibility of selecting more suitable algorithm for particular apex with regard to specific parameters of its phyllotactic system.

scholarly journals Ontogenetic changes of phyllotaxis in Anagallis arvensis L.

2014 ◽  
Vol 64 (4) ◽  
pp. 319-325 ◽  
Author(s):  
Dorota Kwiatkowska
Keyword(s):  
Shoot Apex ◽  
Regular Sequence ◽  
Internode Elongation ◽  
Spiral Pattern ◽  
Ontogenetic Changes ◽  
Flower Buds ◽  
Shoot Apices ◽  
Flower Primordia ◽  
Number Of Leaves ◽  
The Common

During the ontogeny of <i>Anagallis</i> spontaneous changes of phyllotaxis appear in a regular sequence. The initial decussate pattern is followed by spiral Fibonacci phyllotaxis, this in turn, by a trimerous pattern, and finally Lucas spiral phyllotaxis is formed. In the course of the first and most common phyllotactic transition, from the decussate to spiral Fibonacci pattern, changes in primordia arrangement occur only within a limited sector of the apex circumference. In the complementary sector, primordia emerge as if the decussate phyllotaxis continued. It is likely that similar circumferential discontinuity accounts for further transitions. The common ontogenetic sequence of patterns in <i>Anagallis</i> is such that, theoretically, each transition requires minimal changes in shoot apex geometry. Although the meristem in <i>Anagallis</i> is able to produce primordia either in whorls or spirally, the elongated shoots of this plant seem to have leaves exclusively in whorls. It appeared that in shoots with an initially spiral pattern, leaves can be clustered in pseudo-whorls due to the uneven internode elongation. Pseudowhorls are composed usually of three (Fibonacci) or four (Lucas) leaves of successive nodes. The number of leaves in a pseudo-whorl equals the number of leaves positioned on one revolution of the ontogenetic helix, which is different in these two spiral patterns. In shoot apices with whorled phyllotaxis, the leaf and flower primordia of a whorl are of different size. On elongated shoots, flower buds emerging in the axils of leaves of one whorl also differ in size.

scholarly journals Indigenous uses of wild and tended plant biodiversity maintain ecosystem services in agricultural landscapes of the Terai Plains of Nepal

2019 ◽  
Author(s):  
Jessica P. R. Thorn ◽  
Thomas F. Thornton ◽  
Ariella Helfgott ◽  
Katherine J. Willis
Keyword(s):  
Ecosystem Services ◽  
Plant Species ◽  
Monsoon Season ◽  
Vascular Plant ◽  
Evidence Base ◽  
Agricultural Landscapes ◽  
Ecological Resilience ◽  
Structured Interviews ◽  
Vernacular Names ◽  
And Gender

Abstract Background Despite a rapidly accumulating evidence base quantifying ecosystem services, the role of biodiversity in the maintenance of ecosystem services in shared human-nature environments is still understudied, as is how indigenous and agriculturally dependent communities perceive, use and manage biodiversity. The present study aims to document traditional ethnobotanical knowledge of the ecosystem service benefits derived from wild and tended plants in rice-cultivated agroecosystems, compare this to botanical surveys, and analyse the extent to which ecosystem services contribute social-ecological resilience in the Terai Plains of Nepal. Method Sampling was carried out in four landscapes, 22 Village District Committees and 40 wards in the monsoon season. Data collection was based on transects walks to collect plant specimens, structured and semi-structured interviews, and participatory fieldwork in and around home gardens, farms, and production landscapes. We asked 180 farmers to free-list vernacular names and describe use-value of biological material. Uses were categorized into eight broad groupings, and 61 biomedical ailment classifications. We assessed if knowledge of plant species diversity and abundance differed with regard to caste, age and gender. Results Nepalese farmers have a deep knowledge of the use and management of the 390 vascular plant specimens identified, which provide key provisioning, regulating, supporting and cultural ecosystem services. Altogether, plants belong to 75 distinct plant species from 49 phylogenetic families: 56 are used to cure 61 ailments, 27 for rituals, 25 for food, 20 for timber, 17 for fuel, 16 for fodder, 11 for soil enhancement, and 8 for pesticides. Four caste groups have statistically different knowledge, and younger informants report a lower average number of useful plants. Conclusion Agricultural landscapes in Nepal are reservoirs of biodiversity. The knowledge of the use of wild and tended plant species in and around these farms differs by the caste and age group of land manager. Conducting research on agroecosystems will contribute to a deeper understanding of how nature is perceived by locals, to more efficient management and conservation of the breadbasket of Nepal, and to the conservation of valuable, but disappearing traditional knowledge and practice.

Sign in / Sign up

Export Citation Format

Share Document