The Phlox germplasm collection at the OPGC is being developed by acquisition of wild germplasm through collections in native habitats in the USA as well as by obtaining representative cultivars from various nurseries. The wild material consists of some original seed from a few of the species where it has been possible to collect them, and also of clonal material that is maintained in the field and in tissue culture. Much of the collection has been characterized by flow cytometric analysis for total genome size and correlation with ploidy. In addition, a systematic attempt at delineating sexual compatibilities between the various species has also been undertaken. Other analysis include anthocyanidin pattern in flowers.