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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.

A plant clone is a lineage of plants descended from one founder by asexual reproduction. Vegetative propagation, for example rooting several plant cuttings from one stock plant, can multiply a selected genotype while avoiding the reshuffling associated with ordinary sexual reproduction. This is why such methods are useful for maintaining a named cultivar that does not reproduce its characteristics reliably from seeds.^[ref]

A plant clone is defined by descent, not by identical appearance. Its members can experience different light, water or nutrient conditions, and somatic mutations can arise during growth. Shared ancestry consequently does not imply that every phenotype or every later DNA sequence must remain identical.

For an illustrative experiment, divide rooted plant cuttings from the same founder between brighter and dimmer conditions while keeping other conditions comparable. Differences in leaf size need not establish a difference in inherited genotype: the design deliberately holds ancestry relatively constant while changing the environment. Repeating this across several distinct plant clones can test whether different genotypes respond differently, an example of genotype-environment interaction.

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.

Vegetative propagation is asexual reproduction of a plant from vegetative parts, such as a plant stem, leaf or root. In a common artificial example, a detached plant cutting forms new adventitious roots and becomes an independent plant. No union of gametes is needed to produce this descendant. Plant clone describes the resulting lineage; vegetative propagation describes the process.

A soft shoot presents a useful physiological problem: its leaves can lose water before it has a functioning root system. The RHS procedure therefore uses young non-flowering shoots, moist growing medium and a humid enclosure while rooting occurs, followed by gradual exposure to less humid conditions. This is a practical application of the balance between water supply and transpiration, rather than a guarantee that every detached plant stem can regenerate.^[ref]

An experimental rooting comparison should specify both the denominator and the endpoint. If six of ten plant cuttings produce visible adventitious roots by a stated day, the observed rooting fraction is $6/10=0.6$. That hypothetical result measures this protocol and starting material; it is neither a universal property of vegetative propagation nor proof that the remaining four plant cuttings are dead.