- Matricaria maritima
Scentless chamomile (Matricaria maritima) is an annual to short-lived perennial. Considered noxious under the BC Weed Control Act, scentless chamomile is commonly found on low to mid-elevation sites, along roadsides, drainage ditches, fence lines, dry shorelines, hay fields, pastures, and other disturbed areas. Currently found in all agricultural regions of BC, scentless chamomile is a major concern in the Kootenay, Okanagan, Peace River, and Thompson areas.
Scentless chamomile has single, white, daisy-like flowers with yellow centers at the ends of each branched stem. Flowers are odourless when crushed, with semi-erect stems that are smooth and branched with fern-like leaves. Fruits are dark brown, rectangular, with 3 prominent, wing-like ribs on one side and a pale brown broad central area on the other side. Mature plants reach 0.15-1 metre in height.
Scentless chamomile produces rapidly by seed only, with a single plant producing up to 1 million seeds that are mature as soon as the flower forms. Seeds remain viable for up to 15 years in the soil and are readily dispersed by wind or water, on equipment and vehicles, or as a contaminant in soil, fill material, crop seed, and animal feed. Seeds can float on water for up to 12 hours and new infestations are often found around watercourses.
Transportation corridors serve as major sources of infestation and spread, and there is an increased risk of invasion to adjacent agricultural areas and aquatic systems. This plant can infest perennial forage crops and prefers areas with high soil moisture; therefore it is commonly found near ponds, streams, and other areas prone to seasonal flooding. Not eaten by livestock, dense stands of scentless chamomile can reduce crop yields in hay fields, pastures, grain fields, and other cultivated crops.