A group of organisms that is capable of interbreeding to produce fertile offspring. However, this biological test of a species is not always available, so there is also a morphological species concept based on anatomical similarities.

A collection of plant material from a particular location. An accession is assigned an identification number, which usually is preceded by the abbreviation PI (plant identification).

In the evolutionary sense, some heritable feature of an individual's phenotype that improves its chances of survival and reproduction in the existing environment.

The geographic range in which a given population will thrive, generally described in terms of elevation, temperature range, annual precipitation, and other environmental parameters, as well as in geographic terms.

The stock seed produced by the breeder or institution that developed and maintains the cultivar. Used to produce foundation seed. Not normally found in commercial channels; the originator or owner of the variety determines the procedure for producing breeder seed and controls breeder seed distribution.

Process intended to maintain the genetic and mechanical purity and identity of commercially produced seed through all steps of production, harvesting, storage, and conditioning. The certification system involves a limited generation or pedigree system comprising four classes of seed: breeder, foundation, registered, and certified. Each class, excep [..]

The progeny of foundation or registered seed, thus two or three generations removed from breeder seed. Certified seed can be used to produce only common or uncertified seed; it cannot be used to produce any other class of certified seed.

A gradual morphological or physiological change in a group of related organisms across their range, usually associated with environmental or geographic transition.

The process of locating, identifying, and harvesting generally small quantities of plant material.

A scientific study in which many families of a given plant species sampled from an identified geographic area are grown in a common environment. Common garden studies generally include replications in two or more growing environments. Environmentally induced phenotypic differences between the plants are minimized, allowing observation and compariso [..]