Annual or more usually perennial.
Reproducing by seed and by horizontal stems which root at the nodes and form dense patches.
Stems - nearly prostrate, as much as 50cm 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.
Opposite (2 per node), stalkless, ovate (1-2cm long) with pointed tips and covered with hair up to 2mm long (hence the name "mouse-eared").
Flowers white, in compact groups or spreading out with long branches and flower stalks up to 12mm long, sepals 5, green, hairy, (about as long as the 5 white, deeply notched petals), 4-6mm long; seedpod cylindrical and straight or slightly curved, 8-10mm 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 long. Flowering and seed-set continue from late spring until freeze-up in autumn.
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.
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.
A. Plant B. Section of stem with pair of leaves C. Tip of branch with 2 seedpods
2 leaf seedling
Hairy stem with opposite leaf orientation
White flower with 5 deeply notched petals and 5 green sepals