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A cultivar is a selected assemblage of cultivated plants that remains distinguishable, sufficiently uniform and stable in specified characteristics when maintained by appropriate plant propagation. The characteristics may concern form, colour, flowering or other useful traits. A cultivar is a named cultivated selection, rather than simply any individual growing in a garden.^[ref]

The phrase “appropriate propagation” matters. Some cultivars are maintained by vegetative propagation, while others can be maintained through seeds or a repeatable hybrid cross. A cultivar therefore need not consist of just one plant clone.^[ref]

For an illuminating example, suppose a selected plant has a distinctive flower colour. Producing more plants is insufficient if their flowers lose that distinguishing trait. The propagation procedure must retain the relevant combination of characteristics. Conversely, variation in an unselected feature need not invalidate the selection: “uniform” concerns the characteristics that distinguish the cultivar, not absolute identity in every measurable property.

Plant propagation is the production of new plants, including establishment from seeds and multiplication by vegetative propagation. The choice of method matters: ordinary sexual reproduction reshuffles inherited material, whereas vegetative propagation preserves a parental lineage as a plant clone. Thus a named cultivar need not retain its distinguishing features when grown from its own seeds. Plant propagation is broader than either germination or vegetative propagation. ^[ref]

For an illustrative comparison, imagine sowing ten seeds from one parent and rooting ten plant cuttings from that parent. Both procedures can increase the number of plants, but they answer different questions. The seedlings sample offspring produced through fertilization; the rooted plant cuttings can supply repeated representatives of one plant clone. Recording the starting material is therefore essential before treating differences among the resulting plants as differences among inherited genotypes.