Myriophyllum aquaticum

RHS Plant Profile

parrot's feather

Other common names

diamond milfoil, smilax

Synonyms

Myriophyllum brasiliense
Myriophyllum proserpinacoides

Aquatic

This plant is listed on Schedule 9 of the UK Wildlife & Countryside Act as an invasive, non-native species and is banned from sale. See cultivation notes for further details An aquatic perennial with branched, submerged stems clothed in whorls of feathery leaves forming a mat on the surface, and with some erect stems to about 15cm

Position

Full sun

Soil Types

Loam

Max Height

Up to 10 cm

Max Spread

1-1.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1-1.5 metres
Max Height: Up to 10 cm

Growing Conditions

Loam

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

Position

Full sun

Aspect: South–facing or West–facing
Exposure: Exposed or 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): H4

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Haloragaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Submerged
Genus: Myriophyllum can be submerged or marginal aquatic rhizomatous perennials, with finely dissected submerged leaves and small or minute flowers, solitary or in spikes from the leaf axils
Name Status: Correct

How to Grow

Cultivation

This plant is listed on Schedule 9 of the UK Wildlife & Countryside Act as an invasive non-native species. Across the EU, UK and NI it is an offence to plant or cause to grow in the wild plants listed on Schedule 9 of this order. These plants should not be planted or caused to grow in the wild and in addition are banned from sale. Gardeners possessing them should undertake measures to control them. See RHS advice on invasive non-native species for further information

Propagation

See cultivation notes. Spreads by root or stem fragments; all plants in UK are female