Most plant scientists are aware of the rapid loss of biological diversity in particular habitats, such as Ecuador or Brazil. We often associate the threat to biodiversity with places where the situation is extreme. Even in extreme situations, opinions vary concerning appropriate management to preserve genetic resources (Fearnside, 1989, 1993; Long, 1992; Stepney, 1990). The subject often degenerates into a debate concerning whether to take the “holistic approach” to conservation and attempt to save everything, or to take a “marketplace approach” that values only what sells (Namkoong, 1992). To avoid crisis situations, we must manage our genetic resources wisely, recognizing that future generations are impacted by our decisions. To accomplish that objective, we must see through the oversimplification represented by the extreme management alternatives. Plant genetic resources can be characterized within the context of geographic origin, and reasonable strategies to maintain, develop, and use them can be devised. The National Plant Germplasm System (NPGS) provides a national framework for a portion of that work, in relation to selected crop plants and their relatives. Traditionally, the NPGS has pursued the strategy of ex situ conservation to increase access to plant material for systematic evaluation, maintenance, and dissemination to users. Repositories of the NPGS were recently requested to address suitability of the core concept as a management tool. The core concept, as elucidated by Brown (1989), is a series of management decisions for subdividing genetic collections. The primary justifications for creating the core subset are to 1) make the diversity of the collection more quickly and completely accessible to germplasm users; 2) reduce the number of accessions needed to develop testing procedures, while maintaining confidence that the reduced sample size encompasses the total collection variability; 3) facilitate evaluation and genetic characterization of the collection; and 4) facilitate general management. We assessed the core concept to determine if it would be a useful management tool in the evaluation and management of collections in the National Clonal Germplasm Repository for Pecans and Hickories. This repository was designated in 1984. However, the collection of pecan cultivars that forms the basis of the repository was begun in the 1930s by Louis Romberg. He actively acquired pecan cultivars as parents for use in controlled crosses in the early pecan breeding program. Over the years, cultivars have been acquired as they were deemed useful for the breeding program. The Pecan Crop Advisory Committee has recognized the need to increase genetic diversity in the collection, while maintaining the utility of the collection for use in the breeding program. The strategy undertaken differentiates the pecan collection into two groups: the cultivar collection and the provenance collection. The cultivar collection is composed of selected cultivars propagated by the pecan industry, historically and currently. This collection is maintained as grafted trees in several orchards at Brownwood, Texas, with some duplicates maintained in orchards near College Station, Texas. Since most pecan cultivars can be recognized on the basis of nut characteristics, nut samples are maintained as voucher specimens for individual trees in the