The rise of non-native wetland plants

Jonathan Graham

Definition of a non native plant

Plant species introduced (i.e. by human action) outside its natural past or present distribution

and that might survive and subsequently reproduce.

Definition of an invasive plant

An invasive plant is not native to a specific location (an Introduced species); and has a

tendency to spread, which is believed to cause damage to the environment, human economy

and/or human health

Elodea species

Canadian pondweed

Elodea canadensis (first UK record 1836)

Nuttall’s waterweed Elodea nuttallii (first UK record 1966)

Balsams

Indian Balsam

Impatiens glandulifera

Orange Balm

Impatiens capensis

5 non native invasive species

Floating Pennywort Hydrocotyle ranunculoides New Zealand Pigmyweed Crassula helmsii Parrot’s Feather Myriophyllum aquaticum Floating/Water Primroses Ludwigia species Water Fern Azolla filiculoides

Floating Pennywort (first UK record 1990)

Similar species to Floating Pennywort 1

Floating Pennywort

Marsh Pennywort

Hydrocotyle vulgaris

Similar species to Floating Pennywort 2

Frog-bit Fringed Water-lily

New Zealand Pigmyweed Crassula helmsii

Terrestrial form Submerged form (to 3m)

Similar species to Crassula

Water-starworts Nuttall’s Waterweed

Parrot’s-feather Myriophyllum aquaticum

Similar species to Parrot’s-feather

Spiked Water-milfoil Myriophyllum spicatum

Whorled Water-milfoil Myriophyllum verticillatum

Leaf whorls

Rigid Hornwort

Whorled Water-milfoil

Spiked Water-milfoil

Water-violet Hottonia palustris

Typical submerged form Terrestrial Form

Water/Floating-primroses Ludwigia species

Water-primrose

Ludwigia grandiflora

Floating-primrose

Ludwigia peploides

Water Fern Azolla filiculoides

Similar species to Azolla

Duckweeds Fat Duckweed Lemna gibba

Why be concerned about invasive aquatics?

Whorled water-milfoil Crassula

Legislation

Wildlife and Countryside Act 1981 Schedule 9, Section 14(2) prohibits 'planting' or 'causing to grow' in the wild of any plant listed in Part 2 of Schedule 9 – includes: Waterweeds (All Elodea species, Curly Waterweed Lagarosiphon

major) Floating Pennywort Parrot's Feather New Zealand Pygmyweed Crassula Floating/Water Primroses (Ludwigia peploides, Ludwigia

grandiflora, Ludwigia uruguayensis) Water Fern Azolla Water Framework Directive – rivers likely to fail “good ecological quality” if scheduled invasive plants present

How to control invasive aquatics (general)

Early season survey

Control (spraying with Glyphosate – Roundup Bi-active with Topfilm).

Further spraying as required to deal with missed patches or regrowth.

If possible reduce water levels to expose target species (Crassula).

Hand pulling after spraying to remove small regrowth areas.

Follow up (late season) survey.

Rapid follow up control if required (spraying and hand pulling).

Cutting often ineffective, dredging useful (fragments contained and removed).

Coordinated survey, application & monitoring to ensure rapid response.

Biosecurity - remove as much soil/ organic matter as possible from equipment.

Dry equipment thoroughly, collected plant material must be removed

(composted away from water bodies or burnt).

Control of Floating Pennywort 1

Spraying large areas with Glyphosate Hand-pulling regrowth

Control of Floating Pennywort 2

Stunted regrowth of Floating Pennywort after spraying

Marsh Pennywort