  We study the Randic index for cactus graphs. It is conjectured to be bounded
below by radius (for other than an even path), and it is known to obey several
bounds based on diameter. We study radius and diameter for cacti then verify
the radius bound and strengthen two diameter bounds for cacti. Along the way,
we produce several other bounds for the Randic index in terms of graph size,
order, and valency for several special classes of graphs, including chemical
nontrivial cacti and cacti with starlike BC-trees.
