An alkanoid is defined as a tree (in the graph-theoretical sense) whic
h can be embedded in the diamond lattice. It corresponds to a staggere
d conformer of an alkane. A computer program for enumerating non-overl
apping alkanoids is described. In these systems there is no pair of co
alescing vertices. Results for the unbranched and branched alkanoids a
re given separately, and the symmetry groups of the systems are determ
ined.