Agrostemma githago, commonly known as Corn Cockle, is a flowering plant historically found in grain fields across Europe and Asia. This herbaceous annual belongs to the Caryophyllaceae family, also known as the pink or carnation family. While recognized for its distinct purplish-pink blossoms, the plant is also known for its inherent toxic properties. Its historical presence as a companion to cereal crops made it a significant concern for agriculture and public health.
Identifying Corn Cockle
Corn Cockle has several distinguishing physical characteristics. The plant grows with slender, upright stems, growing up to 100 centimeters. These stems are sparingly branched and covered with fine, appressed hairs, giving it a woolly appearance.
Its leaves are narrow, linear-lanceolate, measuring 45 to 145 millimeters long. They are pale green, arranged oppositely along the stem, and held nearly erect. Flowers appear as solitary blooms at the ends of the stems, ranging from deep pink to purple.
Each flower measures up to 5 centimeters in diameter and has five petals, often adorned with two or three discontinuous black lines. Its sepals are much longer than the petals, joined at their base to form a rigid, ten-ribbed tube. The seeds, contained within a many-seeded capsule, are black, kidney-shaped, and have a rough, echinulate-tuberculate surface, measuring 3 to 3.5 millimeters wide.
Agricultural Impact and Toxicity
Historically, Agrostemma githago was a pervasive weed in cereal crops, particularly wheat and rye, throughout agricultural regions. Its seeds, similar in size to grain kernels, would frequently mix with harvested cereals, leading to widespread contamination.
The plant contains toxic compounds, primarily githagin, a type of saponin, and ribosome-inactivating proteins. These saponins are not neutralized by heat, meaning that even flour made from contaminated grain can cause poisoning. When Corn Cockle seeds are ground with cereal grains, the resulting flour can appear discolored with a greyish hue, and have an unpleasant odor and bitter taste.
Ingestion of contaminated grain or products can poison humans and livestock. Symptoms include gastrointestinal distress (nausea, vomiting, diarrhea), abdominal pain, headache, and dizziness. Severe poisoning can lead to seizures, coma, and be fatal. Historical records indicate significant outbreaks, such as 30 documented cases in Poland between 1951 and 1963, which resulted in high mortality rates among pigs, cattle, and horses. Poultry are also particularly susceptible to poisoning from the seeds.
Historical Presence and Modern Rarity
Agrostemma githago was once a common sight across agricultural landscapes in Europe, North Africa, and western Asia, often growing alongside traditional grain crops. Its widespread distribution was largely due to its seeds being inadvertently sown with cereal grains each season.
Over the last century, its populations have declined dramatically. This reduction is primarily attributed to advancements in agricultural practices, including improved seed cleaning techniques that efficiently separate cockle seeds from grain. The widespread adoption of herbicides and modern farming methods, which involve more intensive soil preparation and crop management, have also significantly reduced its ability to compete and reproduce.
As a result, Corn Cockle is now considered rare or even extinct in many areas where it was once abundant. While no longer a common agricultural pest, it occasionally reappears as a casual escape from cultivation or is intentionally grown as an ornamental plant. Certain cultivars, such as ‘Milas’ with pink flowers or ‘Ocean Pearls’ and ‘Sakuragai’ with white flowers, are available for garden use. Despite its rarity, there remains a low risk of it becoming a nuisance if cultivated wild-flower seed mixes containing it escape into natural areas, as it is considered invasive in some regions like West Virginia, Virginia, and Maryland.