  We use a sample of 55 groups and 6 clusters of galaxies ranging in mass from
7 x 10^11 Msun to 1.5 x 10^15 Msun to examine the correlation of the Ks-band
luminosity with mass discovered by Lin et al. (2003). We use the 2MASS catalog
and published redshifts to construct complete magnitude limited redshift
surveys of the groups. From these surveys we explore the IR photometric
properties of groups members including their IR color distribution and
luminosity function. Although we find no significant difference between the
group Ks luminosity function and the general field, there is a difference
between the color distribution of luminous group members and their counterparts
(generally background) in the field. There is a significant population of
luminous galaxies with H-Ks > 0.35 which are rarely, if ever, members of the
groups in our sample. The most luminous galaxies which populate the groups have
a very narrow range of IR color. Over the entire mass range covered by our
sample, the Ks luminosity increases with mass as L ~ M^(0.64 +/- 0.06) implying
that the mass-to-light ratio in the Ks-band increases with mass. The agreement
between this result and earlier investigations of essentially non-overlapping
sets of systems shows that this window in galaxy formation and evolution is
insensitive to the selection of the systems and to the details of the mass and
luminosity computations.
