Photo Credit: John Randall, The Nature Conservancy, Retrieved from Bugwood.org (Image Number: 5391987), used under CC BY-NC 3.0 US, modified from the original
Common Name: Lens-Podded Hoary Cress
Scientific Name: Lepidium chalepense
Habitat: Roadsides, farmland, grassland, grassland dry, grassland wet, disturbed areas
Provincial Designation: Noxious
Noxious weeds are plant species designated in the Alberta Weed Control Act. Noxious weeds must be controlled, meaning their growth or spread needs to be prevented.
Lens-Podded Hoary Cress is native to Europe and Asia and was introduced to North America together with the very similar globe-podded hoary cress in the early 1900s. It was likely introduced as a contaminant of alfalfa seed or horse feed.
Lens-Podded Hoary Cress can be an aggressive invader that can form dense monocultures in open grasslands and riparian areas. It also serves as a host for insect pests that feed on crops.
The flowers are white, 6-10 mm wide, and have four petals. Numerous flowers are borne at the end of the stem in flat topped clusters.
Leaves are grey-green or blue-green in colour, oblong or lance shaped, and 4-10 cm long. The leaves of most plants are covered with soft hairs and clasp the stem. Some plants have short stalked leaves with no hairs.
The fruits of this hoary cress are spherical in shape and have no hairs. Stems are erect, are sometimes hairy, and can grow up to 65 cm tall.
Can Be Confused With
- Shepherd’s Purse - Capsella bursa-pastoris - native plant, ‘weed’, but the seed pods are triangular and stand above the stalk, rather than heart shaped and hanging below as in the Hoary Cress. The leaves are highly variable and the flowers look similar.
- Stink Weed - Thlapsi arvense - introduced mustard, ‘weed’, which has a nasty smell. A variable weed, Stinkweed or ‘Field Pennycress’ tends to be hairless, while the Hoary
- Cresses tend to have hairy stems. Interestingly, this plant is being raised commercially as ‘pennycress’ and is being processed into an ‘natural’ herbicide and biofuel.
- Globe-Podded Hoary Cress - Lepidium appelianum - AND
- Heart-Podded Hoary Cress - Lepidium draba - AND
- Broad-Leaved Pepper-Grass - Lepidium latifolium - AND
- Garlic Mustard - Alliaria petiolata -
- Native Mustards - Brassica species - but all our native mustards are yellow, not white
Please keep your eyes out for this species and report it to firstname.lastname@example.org when in doubt.