What defines a cultivar in horticulture?

A cultivar, short for "cultivated variety," refers to a plant variety that has been selectively bred through cultivation for specific desirable traits. These traits can include characteristics such as flower color, leaf shape, disease resistance, hardiness, or yield. Cultivars are often stable, maintaining their unique characteristics when propagated, which is a key aspect of their definition.

In the context of horticulture, cultivars are significant because they allow growers to choose plants that meet particular aesthetic or practical needs. This selective breeding can enhance performance in various growing conditions or improve the plant's attractiveness for landscape use or commercial production.

The other options do not accurately define a cultivar. While a rare and endangered plant species, hybrids from different species, or plants needing special care may represent interesting horticultural categories, they do not encapsulate the concept of a cultivar focused primarily on selective breeding for specific traits. Therefore, the distinction that cultivars are about the deliberate breeding for superior and stable characteristics is essential to understanding their role in horticulture.