Invasive Species

What are invasive species?

Invasive species can be defined as any non-native organism that can cause harm to the health of humans, the environment or the economy. Alien invasive species are recognized globally as the second largest threat to biological diversity and native species.

What are invasive plants?

An invasive plant can be defined as "a plant that is non-native to the ecosystem under consideration and whose introduction causes, or is likely to cause, economic or environmental harm or harm to human health”. Many invasive plant species have no predators to keep their populations in check.
Click on INVASIVE SPECIES on the left sidebar for more detailed information.

What plants are a priority in the LRISS region?

LRISS has defined categories that prioritize plants for treatment. There are 6 categories that include: Prevent, Eradicate, Contain, Strategic Control, No Action and Insufficient Information. The definitions and full list can be found under our Resources Page. The priority category for the invasive plants featured on our website are found in the description.

Lillooet Plantwise Guide

Click here to access the Lillooet Plantwise Guide, an eBook created by LRISS in partnership with Splitrock Environmental which is intended to provide gardeners and landscapers in the Lillooet Region with information on how to identify the top invasive garden plants and offers native alternatives to "Grow Instead".

List of Priority Invasive Plants:

Blueweed (Echium vulgare L.)

Biennial forb with numerous blue tube flowers on upperside of a short stem. Stems grow 30-80cm tall covered in short hairs. Leaves are also covered in hairs and are narrow (6-25cm


Perennial forb with branched stem and spine-tipped leaves, growing to 2m in height. Bloom period is from June to October; flowers are purplish-pink, about 1cm in diameter, and in c

Common Bugloss (Anchusa officinalis L.)

LRISS Category: Eradicate Biennial or perennial forb with purple-blue flowers with white centers. The flower buds are coiled on their stem and straighten as the flower open. The l


Common burdock is a large, leafy biennial that produces prickly burs. The leaves grow up to 50cm long and 30cm wide, are dark green above and hairy below. Purple flowers form in cl


An aromatic perennial forb with clusters of yellow flowers, growing to 1.5m in height. Bloom period is July to October. Flowers are button-like and yellow, in dense, flat-topped cl


Robust, branched perennial growing up to 1.2m tall. Each plant may have 1-25 flowering stems that bloom from May through September. Flowers are bright yellow with a long spur, rese


Biennial or short-lived perennial in the Asteraceae (sunflower) family. The plant is 10-60cm tall with erect, branching stems with short, stiff hairs. Flowers appear from June - Se


An erect, branched plant growing to 1.1m. A cluster of small white flowers forms at the top of slender stems from June to September. Flowers are 4-6mm long with deeply notched peta

Hoary Cress (Cardaria draba (L.) Desv.)

Perennial forb in the Mustard Family. Grows up to 50cm tall with numerous white flowers with 4 petals giving it a flat-topped appearance. Leaves are alternate, 4-10cm long, blue-gr


A taprooted, leafy plant growing to 1.2m tall. Blooms from June to September. Flowers are arranged in a line along upper stems and are small, reddish-purple, and have five petals.

Japanese Knotweed (Fallopia japonica)

Often called "Bamboo". Rhizomatous perennial with jointed stems growing to 3 m (10 ft) tall. Leaves are alternate on the stem, nearly heart-shaped, dark green on top and paler gree

Leafy Spurge (Euphorbia esula L.)

Designated Provincially Noxious, a perennial forb containing a white, milky latex. Mature plants are 20-90cm tall, smooth stems thickly clustered with yellowish-green small flowers

Orange Hawkweed (Hieracium aurantiacum)

Perennial forb containing milky juice. Orange to red ray flower with notched tips clustered at the top of a leafless stem. Stems are erect with stiff hairs approximately 1.3-1.2m t


A parasitic, annual forb with thread-like yellow to orange stems and no true leaves. The stems adhere to a host plant and coil around the foliage, sometimes forming dense mats. Suc

Sulphur Ciquefoil (Potentilla recta L.)

Perennial forb in the Rose Family. Light yellow (sulphur) flowers with 5 petals, 30-70cm tall on one to several stems growing from the rootstock. Leaves are alternate on the stem a


Tansy ragwort is a biennial or short-lived perennial in the Asteraceae (sunflower) family. The taprooted plants have one or more branched stems, and grow to 1.2m in height. Flat-to

Yellow Flag Iris (Iris pseudacorus)

Perennial in the Iridaceae (iris) family. Grows up to 1.5m in height, with one or more showy yellow flowers per stem. Flowers are large, with three petals facing up, and three larg


Robust, branched perennial growing up to 60cm in height. Each plant may have 1-25 flowering stems that bloom from May through August. Flowers are bright yellow with a long spur, re

Common Bugloss (Anchusa officinalis L.)

A biennial or perennial invasives with deep purple-blue flowers on the ends of coiled inflorescence. The coils open exposing the tubular flowers. Lance shaped leaves are covered in

Cypress Spurge (Euphorbia cyparissias)

Perennial that reproduces by seed and lateral root buds. Grows between 10 and 60cm high with stalkless, lance-shaped leaves that are alternate on the stem. The stems and leaves hav

Himalayan Blackberry (Rubus armeniacus or R. discolor)

Biennial shrub that grows up to 3 metres in height with sharp thorns and black fruit. The stems are 5 angled with toothed, evergreen leaves. The small flowers are white to pink and