Ministry of Agriculture, Food and Rural Affairs

Ontario Weeds: Mouse-eared chickweed

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Excerpt from Publication 505, Ontario Weeds, Order this publication

Table of Contents

1. Name
2. Other Names
3. Family
4. General Description
   • Photos and Pictures
5. Stems and Roots
6. Leaves
7. Flowers and Fruit
8. Habitat
9. Similar Species
10. Related Links

Name: Mouse-eared chickweed, Cerastium fontanum Baumg. ssp. triviale (Link) Jalas

Other Names: céraiste vulgaire, céraiste commun, Cerastium vulgatum L.

Family: Pink Family (Caryophyllaceae)

General Description: Annual or more usually perennial, reproducing by seed and by horizontal stems which root at the nodes and form dense patches.

Photos and Pictures

Mouse-eared chickweed.
A. Plant. B. Section of stem with pair of leaves. C. Tip of branch with 2 seedpots.

Stems & Roots: Stems - nearly prostrate, as much as 50cm (2ft) long, with short upright branches, or stems erect if growing amongst taller plants, densely but very finely hairy, soft, often slightly sticky to the touch, dark green, round in cross-section with swollen nodes;

Leaves: Opposite (2 per node), stalkless, ovate (1-2cm, 2/5-4/5in. long) with pointed tips and covered with hair up to 2mm (1/12in.) long (hence the name "mouse-eared").

Flowers & Fruit: Flowers white, in compact groups or spreading out with long branches and flower stalks up to 12mm (½in.) long, sepals 5, green, hairy, (about as long as the 5 white, deeply notched petals), 4-6mm (1/6-¼in.) long; seedpod cylindrical and straight or slightly curved, 8-10mm (1/3-2/5in.) long, light or straw-coloured, opening at the end with 10 small teeth and releasing many, tiny, reddish-brown, roundish to 4-sided seeds about 0.75mm (1/30in.) long. Flowering and seed-set continue from late spring until freeze-up in autumn.

Habitat: Mouse-eared chickweed is common throughout Ontario and occurs in almost any kind of habitat including gardens, lawns, fields, pastures, meadows, wet depressions, rock outcrops, dry sandy areas, and under moist woods. It is one of the most common and persistent weeds of lawns and occasionally is thick enough to be troublesome in gardens and fields.

Similar Species: It is distinguished from other chickweeds, Grass-leaved stitchwort and Thyme-leaved sandwort by its distinctly hairy stem and stalkless leaves covered with long hair on both surfaces, and its cylindrical, light-coloured seedpods.

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

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