The Zinnia Family Tree
There are more than a dozen species of zinnias, members of the Asteraceae (also known as Compositae) family, but very few of them are grown in home gardens. Zinnia elegans (syn. Z. violacea), the common zinnia, is very familiar to gardeners. Tall, mid-sized, and dwarf varieties of this species have been grown for decades, and flowers are available in a wide range of colors. Z. angustifolia(also known as Z. linearis) is less common in gardens, but is gaining in popularity. The plants have narrower foliage and smaller single flowers. The species has golden-orange flowers, but the variety, ‘Crystal White’, AAS (All America Selections) winner in 1997, offers pure white daisy-like blooms with yellow centers. It is more compact than the straight species, and may overwinter in Zones 9-11. Probably the least known of the garden zinnias is Z.haageana, or the Mexican zinnia. It is disease-resistant, grows to 15 inches, and has small, bicolored flowers.