  The current cosmological paradigm sees the formation and evolution of the
cosmic large-scale structure as governed by the gravitational attraction of the
Dark Matter (DM) and the repulsion of the Dark Energy (DE).
  We characterize the relative importance of uniform and constant dark energy,
as given by the Lambda term in the standard LCDM cosmology, in galaxy systems
of different scales, from groups to superclusters.
  An instructive "Lambda significance graph" is introduced where the matter-DE
density ratio <rho_M>/rho_Lambda for different galaxy systems is plotted
against the radius R. This presents gravitation and DE dominated regions and
shows directly the zero velocity radius, the zero-gravity radius, and the
Einstein-Straus radius for any fixed value of mass.
  Example galaxy groups and clusters from the local universe illustrate the use
of the Lambda significance graph. These are generally located deep in the
gravity-dominated region <rho_M}>/rho_Lambda > 2, being virialized. Extended
clusters and main bodies of superclusters can reach down near the border line
between gravity-dominated and DE dominated regions <rho_M>/rho_Lambda = 2. The
scale--mass relation from the standard 2-point correlation function intersects
this balance line near the correlation lenght.
  The log <rho_M>/rho_Lambda vs. log R diagram is a useful and versatile way to
characterize the dynamical state of systems of galaxies within the Lambda
dominated expanding universe.
