Search PubMed⌕ Search

PubMed · 8868571

Creating phyllotaxis: the stack-and-drag model.

Abstract

The genesis of phyllotaxis, the origin of the pattern of appendages on the surface just below the apical extreme of many plants, is an old unsolved puzzle. Whereas many models generate helices, the stack-and-drag model is the first to achieve this in an integral construction from seed to flower. Combination of the principle of gnomonic growth, where consecutive additions have comparable positions, with a "dragging" principle, where the developing zone follows the apical tip, provides a powerful tool in simulating a wide range of phyllotactic manifestations. The influence of three vital parameters for primordial size, compressibility, and canalization (or annular arrangement) helps in understanding the problem's nature.

Explore related subjects

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

F M Van Der Linden. 1996-04-01. Creating phyllotaxis: the stack-and-drag model.. https://doi.org/10.1016/0025-5564(95)00077-1

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

Equilibrium regained: from nonequilibrium chaos to statistical mechanics.

Far-from-equilibrium, spatially extended chaotic systems have generally eluded analytical solution, leading researchers to consider theories based on a statistical rather than a detailed knowledge of the microscopic length scales. Building on the recent discovery of a separation of length scales between macroscopic behavior and microscopic chaos, a simple far-from-equilibrium spatially extended chaotic system has been studied computationally at intermediate, coarse-grained scales. Equilibrium properties such as Gibbs distributions and detailed balance are recovered at these scales, which suggests that the macroscopic behavior of some far-from-equilibrium systems might be understood in terms of equilibrium statistical mechanics.

Mathematics↗

Modelization of the role of currents and turbulence on the growth and dispersion of marine phytoplankton.

This note introduces a model of growth and dispersion of marine phytoplankton, focusing on the effects of currents (3D) and vertical mixing. Our method consists in describing these effects as the product of the horizontal current, which is solved along characteristic lines, and the coupled action of vertical current and vertical diffusion, restricted on each characteristic line of the horizontal current. One thus obtains explicit formulae, which it will be possible to use in the study of the phytoplankton distribution.

Mathematics↗

Dose calculation for asymmetric photon fields with independent jaws and multileaf collimators.

We have developed a simple method for dose calculation in dual asymmetric open and irregular fields with four independent jaws and multileaf collimators. Our calculation method extends the scatter correction method of Kwa et al. [Med. Phys. 21, 1599-1604 (1994)] based on the principle of Day's equivalent-field calculation. The scatter correction factor was determined by the ratio of the derived doses of a smaller asymmetric open field or irregular field to a larger symmetric field. The algorithm with the scatter correction method can be calculated from output factors, tissue maximum ratios, and off-axis ratios for conventional symmetric fields. The doses calculated by this method were compared with the measured doses for various asymmetric open and irregular fields. The agreement between the calculated and measured doses for 4 and 10 MV photon beams was within 0.5% at the geometric center of the asymmetric open fields. For the asymmetric irregular fields with the same geometrical center, agreement within 1% was found in most cases.

Mathematics↗