Ontario Weeds: Stinkweed
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Excerpt from Publication 505, Ontario Weeds,
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Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Leaves
- Flowers and Fruit
- Habitat
- Similar Species
- Caution
- Related Links
Name: Stinkweed, Thlaspi arvense
L.,
Other Names: Fanweed, Field pennycress,
Frenchweed, Pennycress, tabouret des champs, thlaspi des champs,
monayère
Family: Mustard Family (Cruciferae)
General Description: Annual or winter
annual, reproducing only by seed.
Stinkweed. A. Base of plant. B. Flowering and fruiting stem.
Stems & Roots: 5-60cm (2in.-2ft)
high, erect, branching in the upper part and sometimes also near
the base, hairless;
Leaves: The first several leaves usually
in a basal rosette at the ground surface, these with stalks and
smooth or slightly wavy margins; lower stem leaves with shallow,
irregular teeth, rounded towards the tip and tapering towards the
narrow stalk which has 2 little lobes or auricles which clasp the
stem; middle and upper leaves shallowly or sometimes deeply toothed,
without stalks but with a pair of lobes at the base which strongly
clasp the stem.
Flowers & Fruit: Flowers white,
very small (about 3mm, 1/8in. across) in rounded clusters at the
ends of branches; seedpods very flat, rounded to oval, 8-12mm (1/3-½in.)
wide and usually a bit longer; the central seed-containing portion
slightly thickened but surrounded by a broad flat wing with a narrow
deep notch at the tip, in the centre of which are the remains of
the tiny style; seed-containing section divided into 2 compartments
by a very narrow septum (membranous partition), each side containing
3 to 8 seeds; this white septum often remaining on the plant after
the pod breaks apart to release the seeds; seeds reddish-brown to
purplish or blackish, ovoid but somewhat flattened, 1.5-2mm (1/16-1/12in.)
long with several rows of concentric ridges on each side. Flowers
from early spring to late fall.
Habitat: Stinkweed occurs throughout
Ontario in cultivated fields, waste places, roadsides and gardens.
Similar Species: It is distinguished from
the pepper-grasses, which it closely resembles, by the complete
absence of hair from stems and leaves, its unpleasant odour and
its larger flat seedpods with a broad flat wing.
Caution: The whole plant has a sour turnip-garlic odour which is distasteful to most people, and causes tainted milk when dairy cattle eat it.
Related Links
... on general Weed
topics
... on weed identification, order OMAFRA
Publication 505: Ontario Weeds
... on weed control, order OMAFRA
Publication 75: Guide To Weed Control
For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca