This usually includes a herbarium specimen and a description. The standard may only be a description or illustration and in the case of grain crops it is usually just a sample of seed. F1 hybrids, which require to be re-created for each new generation, qualify as cultivars if the cross produces stable, repeatable forms. Clones can be created in a variety of ways. For example, they may be taken from parts of the plant which result in a particular growth habit as when prostrate plants are derived from cuttings of lateral branches.
Some clones maintain a particular phase of the plants life cycle.
For example many Ficus cultivars are selected from forms of juvenile leaves that are maintained in a juvenile state. A common source of new cultivars is aberrant growth such as variegation of leaves. To find out more about cultivars, visit the web site of the International Cultivar Registration Authority .