Narcissi join tulips, hyacinths and crocuses to make up the most important of the spring-flowering bulbous, cormous and tuberous plants. Narcissi are used in abundance in gardens. This has much to do with their winter hardiness, the ease with which they naturalize, and their many applications. The various colours and flower types available also play a role in their popularity. The large-flowered yellow daffodils in particular are the flowers that promise that the warm spring air is on the way. The number of wild species varies widely, depending on how one defines 'wild species'. Usually this number is limited to 26 (not counting the subspecies and varieties). In addition to these, many hundreds of cultivars are known. The most important colours are yellow, white, orange-red, orange and salmon. Many cultivars display marked or subtle differences in colour between the corona (trumpet or cup) and the perianth (petals).