Speedwell Weed (Veronica spp).

Four speedwells (Veronica spp.) turn up in Australian lawns and turf. Two are annuals that spread by seed: birdseye speedwell and field speedwell. Two are perennials that form mats and spread by creeping stems: thyme-leaved speedwell and slender speedwell. The difference matters for control: you beat an annual by stopping it setting seed, but that does nothing to a perennial mat.

All four like moist soil. They die back in dry spells and regrow after rain.

After you read this, you will be able to:

• Identify these weeds.
• Know their habitat.
• Know the best cultural and chemical way to control them.

Speedwell Weed Identification.

Speedwells have small, rounded to oval leaves and small four-petalled flowers, usually blue to lilac, borne in the leaf axils along the stems.

Category: broadleaf (dicot) weeds.

Photosynthetic pathway: C3. They grow most in the cool months, which is why they are a late winter and spring problem.

Birdseye speedwell (Veronica persica).

Also called Persian speedwell or common field speedwell. Creeping speedwell is a different plant; see slender speedwell below.

• Growth habit: a prostrate, sprawling annual with weak stems whose tips turn upward.
• Leaves: broadly ovate, coarsely toothed and hairy, 1 to 2 cm long. The largest leaves of the four.
• Flowers: about 1 cm across, sky blue with darker stripes and a white centre, each on its own long, slender stalk.
• How it spreads: mainly by seed, which it sets in large numbers. Stem fragments can also regrow.
• Habitat: disturbed soil, thin lawns and garden edges.
• Control: it is low enough to escape the mower, so it seeds freely in thin turf.

Field, Corn or Wall Speedwell (Veronica arvensis).

• Growth habit: a small, upright winter annual, usually under 15 cm tall. It germinates in autumn and flowers in spring.
• Leaves: hairy. The lower leaves are round to ovate; the upper ones are narrower and clasp the stem.
• Flowers: tiny (about 2 to 4 mm) and blue to lilac, often hidden among the upper leaves. They only open on bright days.
• How it spreads: by seed only.
• Habitat: dry, sandy soils, often along walls and paths. It is found in Canberra and the Southern Tablelands.

Thyme or Turf Speedwell (Veronica serpyllifolia).

• Growth habit: a low-growing perennial that forms dense mats.
• Leaves: small, nearly hairless, round to oval and opposite, like the leaves of thyme.
• Flowers: pale lilac-blue to white with dark lines, 4 to 6 mm across.
• How it spreads: mainly by creeping stems that root at the nodes, and also by small seeds.
• Habitat: damp lawns and shady areas.

Slender or creeping speedwell (Veronica filiformis).

• Growth habit: a creeping perennial that forms dense mats. Its thin stems root wherever a node touches the soil.
• Leaves: rounded to kidney-shaped with scalloped edges, about 5 to 10 mm across. Smaller than birdseye speedwell, larger than thyme-leaved speedwell.
• Flowers: about 8 to 10 mm across, pale blue to lilac with darker stripes, each on a long, thread-like stalk.
• How it spreads: almost entirely by stem fragments. It is self-sterile and rarely sets seed. Mowing chops the stems up and carries the pieces across the lawn, so cutting an infested patch spreads it.
• Habitat: lawns and other mown grass, usually where it is damp.

A Comparison Table of The Veronica species.

For more information, please check out our weed ID chart. Speedwell is a good indicator weed of wet soils and shade.

Comments: most vegetative growth occurs in cool weather in late winter and early spring.

The image below is courtesy of Massey University.