  As stars which have planetary systems evolve along the red giant branch and
expand, they interact with the close planets. The planets deposit angular
momentum and energy into the red giant stars' envelopes, both of which are
likely to enhance mass loss on the red giant branch. The enhanced mass loss
causes the star to become bluer as it turns to the horizontal branch. I propose
that the presence of planetary systems, through this mechanism, can explain
some anomalies in horizontal branch morphologies. In particular, planetary
systems may be related to the ``second parameter'', which determines the
distribution of horizontal branch stars on the Hertzsprung-Russel diagram. The
proposed scenario predicts that surviving massive planets or brown dwarfs orbit
many of the extreme blue horizontal branch stars, at orbital periods of tens
days.
