The poppy family's tenacious, drought-resistant nature belies its delicate flowers. The thin-petalled flowers bob and nod charmingly in every breeze, and the cup-shaped blooms and deeply scalloped, soft green leaves are characteristic of every poppy species. While poppy species share many characteristics, they do have significant differences.
Iceland poppies (P. nudicaule) are among the smallest of the poppy family. They grow just 12 to 24 inches tall, but Iceland poppies produce their 2- to 3-inch flowers from spring to midsummer, longer than most members of the poppy family. The flowers appear in shades of orange, red, yellow and white. Their divided leaves are hairy, unlike their small cousin the alpine poppy (P. alpinum). This perennial is short-lived, even acting as an annual in hotter climates.
Oriental poppies are perennials for zones 4 to 9, but, like their Icelandic cousins, don't thrive in mild-winter gardens. They are not shy, delicate plants -- they produce 3-feet-tall mounds of deeply lobed, long, grey-green leaves covered with fine hairs, and their midsummer flowers may be up to 6 inches wide. Varieties bloom in shades of show-stopping reds, oranges, brilliant yellows, pastels and whites. Most varieties have a rounded, black splotch at the base of each petal. Oriental poppies don't like summer heat and die back, but restart growth in the fall.
Corn poppies (P. rhoeas) appear identical to oriental poppies at first glance. They share a similar size, growing 2 to 5 feet tall, and the American Legion corn poppy has bright scarlet flowers with black spots on the petal base, similar to oriental poppies. Corn poppies bloom in shades of red, white or orange. Shirley poppies, a pastel variety of corn poppy, do not have the traditional dark patch at the flower's centre. All corn poppies have one easily identifiable characteristic -- they are annuals and do not restart growth in the fall.
Breadseed or birdseed poppies (P. somniferum) have large, eye-catching seedheads, 4- to 5-inch flowers in red, white or purple and, as their name implies, produce seeds for your bread or bagels. Most gardeners never acquire this poppy, however, because it's also the source of opium. The Elka strain produces white seeds, while Ziar produces white and lavender flowers. In contrast, California poppies (Eschscholzia californica) have deeply cut, blue-green leaves and clear, vivid yellow or orange flowers. They are remarkably adaptive and may be invasive, but are not hardy below -6.67 degrees Celsius.