White cockle has strikingly lovely white flowers and the fuzzy, almost furry opposite leaves give it a distinctive appearance.
It is a member of the Pink family — it looks like pinking shears gave the five petals their deep notches. The Pink family includes chickweed and night flowering catchfly — catchfly is often mistaken for White cockle, but is much stickier and only blooms at dawn, dusk, and on overcast days.
White cockle has male and female plants, both are about one metre high with oblong, pointy leaves emerging across from each other (opposite) from swollen nodes. The lower leaves are stalked while the upper ones are stalkless. This weed can act as an annual, biennial, winter annual, or even a short-lived perennial, allowing it to adapt to any type of crop or habitat.
Often a problem in hay and pasture (but also in annual crops), it produces seed extremely quickly and the seed is similar in size to many forages (clover, alfalfa, timothy). So always ask for the Certificate of Seed Analysis when buying forage seed and reject any lot with this (or any) invasive weed.
Although spread only by seed, its massive root system keeps the plant alive through difficult conditions, robbing the soil of moisture and nutrients. Hand-picking is almost fruitless, and tillage can “transplant” the roots if the root system isn’t destroyed.
Although White cockle is an introduced species, it can be found throughout Alberta. Check out the Weed Survey maps under the “Maps and Multimedia” section of the Alberta Agriculture and Forestry website.
By Normand Boulet, agricultural fieldman, MD of Smoky River