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:

Baby’s Breath (Gypsophila paniculata)

Tumbleweed perennial growing up to 1m tall. Originally from Europe and now grown for floral arrangements. Small white flowers with slender leaves covered in a powdery white film.&n

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

Canada Thistle (Circium arvense)

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

Chicory (Cichorium intybus L.)

Chicory is originally from Eurasia. It has blue flowers and grows between 0.3 and 1.8 metres. The leaves are long, lance-shaped and toothed. It flowers from July to September. LRI

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

Common Burdock (Arctium spp.)

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

Common Tansy (Tanacetum vulgare L.)

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

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

Dalmatian Toadflax (Linaria dalmatica)

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

Diffuse Knapweed (Centaurea diffusa)

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

Eurasian Watermilfoil (Myriophyllum spicatum)

Aquatic green perennial that is submersed in water with finely dissected leaves. It becomes limp when removed from water. It can grow up to 4 metres in depth. The leaves are arrang

Field Scabious (Knautia arvensis (L.) Coult.)

Field Scabious is a perennial forb with blue to purple flowers. The flowers are on the end of long stalks. The stems are hairy and the leaves are basal. The leaves are feather-shap

Flat Peavine (Lathyrus sylvestis)

This is one species of 4 Lathyrus species known in BC. It is a perennial vine that can grow up to 7 feet long and climb using tendrils. The leaves are 3 inches long and 1 inch in w

Giant Hogweed (Heracleum mantegazzianum)

WARNING: DO NOT TOUCH THIS PLANT! Giant Hogweed is a perennial herb that grows up to 5 metres tall (16 feet). It looks very similar to the native cow parsnip (Heracleum maximum). I

Hoary Alyssum (Berteroa incana (L.) DC)

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 notchedpet

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-

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

Hound's Tongue (Cynoglossum officinale L.)

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

Nodding Thistle (Carduus nutans L. spp. leiophyllis (Petrovic))

It is a biennial forb with single, large reddish-purple flowers (up to 5cm) that nod. It is originally from Eurasia and North Africa. They grow up to 2.4m tall with spiny, deeply l

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

Oxeye Daisy (Leucanthemum vulgare Lam.)

Oxeye Daisy is a short-lived perennial that grows between 20 and 80 cm tall. It is originally from Eurasia. It reproduces both by seed and vegetatively from the roots. Some plants

Parasitic Dodder (Cuscuta spp.)

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

Poison Hemlock (Conium maculatum)

It is a biennial forb with white flowers in umbrella-like clusters supported by a stalk. The leaves are fern-like, finely divided and segmented on short stalks. The leaves smell mu

Puncturevine (Tribulus terrestris L.)

Puncturevine is an annual forb that grows in spreading stems forming mats up to 100 cm wide. It has yellow flowers with 5 petals that form into sharp pointed fruits 2-6mm long with

Purple Loosestrife (Lythrum salicaria L.)

A perennial plant that often grows near or in water. The purple flowers grow around the stem in a spike form. They have 5-7 petals. Leaves are lance-shapped and either opposite or

Scentless Chamomile (Matricaria perforata)

A daisy that grows up to a metre tall with smooth, narrow lance-shaped leaves. The leaves have a fern-like look. This plant can be an annual, biennial or short-lived perennial. Flo

Spotted Knapweed (Centaurea stoebe)

Spotted knapweed is a biennial or a short-lived perennial. It has spotted in the name because under its pink flowers, the floral bracts are tipped black and look like spots. It rep

St. John’s Wort (Hypericum perforatum L.)

This plant is a perennial forb that grows up to 1 metre high. It has bright yellow flowers in flat-topped clusters. The leaves are oval-shaped covered in transparent dots and has p

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 (Senecio jacobaea L.)

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

Wild Chervil (Anthriscus sylvestris)

Wild Chervil can be an annual, biennial or a short-lived perennial forb. It grows up to 1.8 tall and has small white flowers. The flowers grow in umbrella-like clusters on 2cm stal

Wild Parsnip (Pastinaca sativa L.)

This species is in the PREVENT category. More information will be added soon. In the meantime, please refer to Ontario's references here: Wild Parsnip Facts from Ontario's Invadi

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

Yellow Toadflax (Linaria vulgaris)

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