Of the world's 100-plus species of poppies (Papaver spp.), only a few are garden subjects. They generally have flamboyant flowers with crinkly, thin petals and intense colors. In the center of the flower, a rounded ovary is surrounded by a ring of stamens. Petals often have dark blotches at the base. Most garden poppies aren't poisonous to humans, but the opium poppy (Papaver somniferum), which is illegal to grow in the U.S., can cause human poisoning if eaten.
Opium Poppy Poisoning
The opium poppy (Papaver somniferum) is native to Eurasia and grows worldwide as an annual plant. It is famous as the source of the addictive narcotics opium and morphine. Toxic alkaloid compounds have the highest concentration in the milky sap present in all parts of the plant, especially in the unripe fruits. The North Carolina State University Cooperative Extension Service characterizes opium poppy as highly toxic, and it may be fatal if eaten. Symptoms are stupor, coma, shallow and slow breathing, respiratory and circulatory depression. Poppy seeds don't contain any harmful compounds and are edible. The organization Calflora lists minor toxicity from dermatitis for opium poppy.
Iceland Poppy Effects
The widely grown ornamental Iceland poppy (Papaver nudicaule) also contains alkaloid compounds in all parts of the plant. They are different chemicals from those in opium poppy, and they don't seem to harm humans. However, livestock can be affected. When horses, cattle and sheep ate discarded Iceland poppy plants, they were poisoned, notes the Canadian Biodiversity Information Facility. Iceland poppies prefer areas with cool summers, where they are perennials. In U.S. Department of Agriculture plant hardiness zones 6 and above with warmer weather, they act as annuals or biennials.
Flanders Poppy Effects
Native to Europe, Flanders poppy (Papaver rhoeas) is also called corn poppy or field poppy, and is the symbol for remembrance on Memorial Day. This annual is a wildflower and a weed in its native range. The "Shirley" cultivar of the European field poppy (Papaver rhoeas "Shirley") is a multi-colored garden cultivar. This poppy also causes livestock poisoning if eaten in large quantities due to various alkaloids present in all plant parts. Human poisoning is unlikely. Plant leaves, stems and sepals have long hairs, which can cause human dermatitis.
Oriental Poppy Effects
Reaching 2 to 4 feet tall in bloom, Oriental poppy (Papaver orientale and hybrids) are perennials grown for their large, bowl-shaped, white, pink, red, scarlet or orange flowers. They require winter chilling for best growth and are recommended for USDA zones 2 through 8. They may grow in warmer areas but only last a year or two. The Canadian government comments that Oriental poppy contains alkaloids that can be physiologically active in animals, but that no poisonings under natural conditions occurred. They recommend removing all old plant parts from gardens so animals don't eat them.