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Common Name: Globe-Podded Hoary Cress

Scientific Name: Lepidium appelianum

Habitat: roadsides, disturbed areas, farmland, grassland, grassland dry, grassland wet

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.

Origin

Globe-podded hoary cress is native to Europe and Asia. Together with the closely related lens-podded hoary cress, it was introduced to North America in the early 1900s. It was likely introduced as a contaminant of alfalfa seed or horse feed. The seeds have been used to make a pepper substitute, hence the common name of pepper-grass.

Legislated Because

Globe-podded hoary cress can be an aggressive invader that forms dense single plant type stand (monocultures) in open grasslands and wet areas. It also serves as a host for insect pests of crops.

Description

This weed has 5-8 mm wide white flowers with four petals. All the Brassica (mustards and cabbage) species - including hoary cresses -  have 6 stamens (male parts): 4 tall and 2 short. Numerous flowers are borne at the end of the stem in flat-topped clusters.

The leaves are 1-5 cm long, covered with soft hairs, grey-green or blue-green in colour, and usually clasp the stem. The leaf shape is oblong or lance-shaped and the leaf edges are toothed. 

A key characteristic of this weed is that is has inflated spherical fruits that are covered in short simple hairs.

Stems are erect, sometimes have hairs, and grow 15-35 cm high.

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 a ‘natural’ herbicide and biofuel.

Native Mustards - Brassica species - but all our native mustards are yellow, not white.

Learn more about this species:

See Fact Sheet - Alberta Invasive Species Council

For More Information

Weed Management

Telephone

In Edmonton: 311

Outside Edmonton: 780-442-5311

Email invasiveweeds@edmonton.ca

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