Ordination techniques seem hitherto not to have been applied to two problems of considerable botanical interest: (i) the ordination of a set of groups after a numerical classification, and (ii) the ordination of an asymmetric system. The botanical contexts in which these problems arise are discussed. It is shown that Gower's "principal coordinate analysis" can be simply extended to cover these two cases; computer programming requirements are minimal, and standard programmes are available for the Control Data 3600 computer.