The lineage of modern zinnias is too complicated to describe. Most are still known as Zinnia elegans, even though they have been bred extensively with several other specie to produce an impressive variety of flower forms and colors. The shortest varieties get only a few inches tall. Big varieties get about two and a half feet tall.
The two to five inch wide flowers, which bloom in phases from spring until autumn, can be yellow, orange, red, purple, pink, salmon, peach, chartreuse or bronzy brown. Some are striped or freckled.
Some flowers look like colorful daisies, with big petals (ray florets) neatly and flatly arranged around prominent centers (disc florets). The overly abundant petals of pom-pom types make rounded blooms with nearly obscured centers. Most are fuller than the daisy types, but not as plump as pom-poms.
Zinnias are warm season annuals that like good exposure and rich soil. The paired leaves are slightly raspy, like kitten tongues, and can be susceptible to powdery mildew. Deteriorating flowers should be deadheaded, although a few can be left for seed.