Weed Seed: Lepidium draba subsp. draba (Heart-pod hoary cress)

Family

Brassicaceae

Synonyms

Cardaria draba

Common Name

Heart-pod hoary cress

Regulation

Primary Noxious, Class 2 in the Canadian Weed Seeds Order, 2016 under the Seeds Act.

Distribution

Canadian: Occurs in AB, BC, MB, ON, SK and rare in NS, QC (Francis and Warwick 2008^Footnote 1).

Worldwide: Native to northern Africa, central and eastern Europe and temperate Asia. Introduced in North America, South Africa, Australia, New Zealand, Argentina, Chile, and beyond its native range in Europe (USDA-ARS 2016^Footnote 2). Found throughout the United States but particularly invasive in the western states (Francis and Warwick 2008^Footnote 1).

Duration of life cycle

Perennial

Seed or fruit type

Seed

Identification features

Size

Seed length: 2.0 - 2.5 mm
Seed width: 1.5 mm
Seed thickness: 1.0 mm

Shape

Seed oval, compressed, the hilum area is flattened

Surface Texture

Seed roughened with faint reticulation

Colour

Seed reddish-brown

Other Features

The pods are heart-shaped, 2.5 - 6.0 mm long and 4.0 - 6.0 mm wide, usually hairy
Seed is ovate in cross section, usually with a furrow between the radicle and cotyledons.

Habitat and Crop Association

Cultivated fields, old fields, gardens, parks, woodlots, orchards, pastures, rangelands, meadows, riparian areas, roadsides, railway lines and disturbed areas (Darbyshire 2003^Footnote 3, Francis and Warwick 2008^Footnote 1, CABI 2016^Footnote 4).

A weed of corn, cereals, potatoes, sugarbeet, sunflower, tobacco, vegetables, alfalfa and vineyards in Europe and a common weed of barley and oats in Canada (CABI 2016^Footnote 4).

General Information

Heart-pod hoary cress was probably introduced into North America in the 19th century as an ornamental or garden plant (Francis and Warwick 2008^Footnote 1).

Similar species

Globe-pod hoary cress (Lepidium appelianum)

Globe-pod hoary cress seeds are a similar size, rough surface and oval shape as heart-pod hoary cress.
Globe-pod hoary cress seeds are a lighter colour and oval-shaped in cross-section with no constrictions like heart-pod hoary cress.

Lens-pod hoary cress (Lepidium chalepense)

Lens-pod hoary cress seeds are a similar size, roughened surface and oval shape as heart-pod hoary cress.
Lens-pod hoary cress seeds are a lighter colour with no surface reticulation like heart-pod hoary cress.