Which species includes variations such as the Canna lily?

Canna x generalis is the correct answer because it is a hybrid species that encompasses many of the cultivated varieties commonly referred to as Canna lilies. This species is known for its vibrant flowers and lush foliage, making it a popular choice in gardens and landscapes. The hybrids offer a diverse range of colors, sizes, and growth habits, which is characteristic of Canna lilies, providing gardeners with many selection options.

In contrast, the other species mentioned, while they are indeed part of the Canna genus, do not represent the broad range of cultivars typically associated with Canna lilies. Canna indica and Canna flaccida, for example, are specific species with distinct traits and are not as widely cultivated for ornamental purposes as Canna x generalis. Canna lutea is another species known for its specific attributes but lacks the hybrid diversity that gives Canna x generalis its recognized status in horticulture. Thus, the hybrid designation of Canna x generalis captures the essence of what is commonly identified as Canna lilies in gardens.