Seeds still sold in 'wildflower' seed mixes
15 non-native species recorded in BC
Introduced from Europe by gardeners as an ornamental and medicinal plant

Orange hawkweed (Hieracium aurantiacum)
&
Invasive yellow hawkweed
(Hieracium and Pilosella spp.)

Identification

Orange hawkweed:

Brilliant orange flowers
A single stem with black hairs and a rosette of leaves at the base of the plant

Yellow invasive hawkweeds:

A complex group of several introduced hawkweeds including yellow hawkweed (Hieracium pratense), meadow hawkweed (H. pilosella), yellow devil hawkweed (H. floribundum) and king devil hawkweed (H. piloselloides)
They are a very difficult group to distinguish from native hawkweeds and each other
Invasive species spread mainly by wind blown seeds and aboveground runners (stalons)
Detailed identification key found here

Flower
The flowers of both orange and yellow hawkweeds are found in clusters of several flower heads at the top of a single stem.

Leaves & Stems
Leaves found in rosette formation at the base of the plant. They are oval and covered in hairs. A single, fibrous stem reaches between 30 and 60 cm in height and is covered in green or black hairs. When broken, leaves and stem release a milky latex.

Impact
Invasive hawkweeds spread rapidly and choke out grasses and native plants, reducing biodiversity and damaging ecosystems. This reduces forage for both wildlife and livestock.

Management
Hawkweed is being treated with herbicide outside of the containment lines along some roads. Changing nitrogen levels in the soil can help control hawkweed and there are a number of very effective herbicides for hawkweed.

Roots
Shallow fibrous roots grow horizontally and create dense mats in the soil.

Reproduction & Dispersal
Hawkweeds spread by seeds, stalons, and subsurface lateral roots which make digging an ineffective treatment.

Seeds

A 1 m square patch of orange hawkweed can produce over 40,000 seeds per year. Each flowerhead can produce between 12 and 30 small, black, ribbed seeds that remain viable in the soil for up to seven years

Preferred Habitat
Hawkweeds prefer course, well-drained soils that are low in organic matter and spread quickly through fields, gravel pits, and along roadsides.

Interesting Facts
Introduced as an ornamental plant from central and northern Europe. It is still sold in 'wildflower' seed mixes despite its damaging impact on invaded sites

Seeds still sold in 'wildflower' seed mixes

Orange hawkweed (Hieracium aurantiacum) & Invasive yellow hawkweed (Hieracium and Pilosella spp.)

Identification

Flower The flowers of both orange and yellow hawkweeds are found in clusters of several flower heads at the top of a single stem.

Leaves & Stems Leaves found in rosette formation at the base of the plant. They are oval and covered in hairs. A single, fibrous stem reaches between 30 and 60 cm in height and is covered in green or black hairs. When broken, leaves and stem release a milky latex.

Impact Invasive hawkweeds spread rapidly and choke out grasses and native plants, reducing biodiversity and damaging ecosystems. This reduces forage for both wildlife and livestock.

Management Hawkweed is being treated with herbicide outside of the containment lines along some roads. Changing nitrogen levels in the soil can help control hawkweed and there are a number of very effective herbicides for hawkweed.

Roots Shallow fibrous roots grow horizontally and create dense mats in the soil.

Reproduction & Dispersal Hawkweeds spread by seeds, stalons, and subsurface lateral roots which make digging an ineffective treatment.