Callitriche palustris

RHS Plant Profile

star grass

Other common names

star grass, water chickweed, water fennel, water starwort

Synonyms

Callitriche verna, Callitriche vernalis

Aquatic Herbaceous Perennial

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An evergreen aquatic perennial plant with a mat-forming habit, reaching up to 10 cm in height and spreading extensively across water surfaces. It features bright green, linear submerged leaves and broader floating leaves, with inconspicuous greenish-white flowers appearing in summer

Position

Full shade, Full sun, Partial shade

Soil Types

Loam

Max Height

Up to 10 cm

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 2–5 years
Max Spread: 0.1-0.5 metres
Max Height: Up to 10 cm

Growing Conditions

Loam

Moisture: Poorly–drained
pH: Acid or Alkaline or Neutral

Position

Full shade Full sun Partial shade

Aspect: East–facing or South–facing or West–facing
Exposure: Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H5

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Plantaginaceae
Native to GB/Ireland: Yes
Foliage: Evergreen
Habit: Matforming, Submerged
Genus: Callitriche can be terrestrial or aquatic perennials with slender stems bearing linear or spoon-shaped leaves and minute flowers in summer, useful oxygenating plants for ponds
Name Status: Correct

How to Grow

Cultivation

Thrives in shallow aquatic habitats like ponds, lakes, slow-moving streams, and marshes, preferring sheltered positions in full sun to partial shade in consistently moist or submerged conditions

Propagation

Propagate by division

Suggested planting locations and garden types

Cottage and informal garden
Wildlife gardens

Pruning

No pruning required, limit spread as required

Pests

Generally pest-free

Diseases

Generally disease-free