White cockle perennial likes full-sun and rich soil, says abinvasives.ca. It is common in hay fields and amid grass.
Alberta Invasive Species Council says, “white cockle can be a serious economic problem as its seeds are difficult to separate from alfalfa, clover and some grass crop seeds – and this invader is an extremely heavy seed producer.
“Stems are hairy, grow 30 to 120 cm tall, and can be erect or spread laterally. There can be several stems per plant – crowded plants branch in the upper stems. Stems are swollen at the nodes.
“Leaves are opposite, hairy, and lance or slightly oval-shaped with pointed tips. Basal leaves and upper stem leaves are smaller.
“Flowers are numerous, fragrant and arranged in spreading clusters. The white (or pinkish) flowers have five notched petals (looks like 10 petals) and only open in the evening. The tubular calyx surrounds the flower’s base. The calyx of the male flower has 10 veins, and the female’s 20 veins are longer, and inflate with ripening.
“Seeds: the calyx matures into a fruit with 10 teeth at the tip containing many tiny, grayish seeds.”
There are herbicides which target cockle and frequent mowing reduces seed production, but cultivation usually spreads the plant.
In Alberta, land owners are required to control noxious weeds.