Hieracium canadense (Canada hawkweed)

Hieracium canadense Michx.

Canada hawkweed, narrowleaf hawkweed, northern hawkweed, Canadian hawkweed

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Asteridae	A large class that encompasses asters
Order	Asterales	Flowering plants with a central disk flower and surrounding petals, like daisies
Family	Asteraceae	The aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
Genus	Hieracium	From Greek hierakion, “a hawk,” from Pliny’s belief that hawks strengthened their eyesight by eating these plants
Species	canadense	“From Canada” (and the rest of the temperate northern hemisphere)

About plant names...

Canada hawkweed is native to temperate climes of Europe, Asia, and North America. Pliny the elder maintained that hawks feed on hawkweeds to improve their remarkable eyesight, hence the name.

If you want to start a bar fight, just ask somebody the scientific name of Canada hawkweed. (This might work best at a bar outside of a botanical convention.) In addition to Hieracium canadense, this species is often referred to as Hieracium kalmii, or Kalm’s hawkweed, after Swedish-Finnish explorer and naturalist Pehr Kalm (1715-1779). The taxonomy of hawkweeds is contentious; the Flora of North America refers to this species as Hieracium umbellatum and mentions that this supersedes the “illegitimate name” Hieracium canadense var. kalmii. So that’s four different current names. Hawkweeds as a group have been classified into as many as 9,000 variants over time. Hawkweeds are unusual because they reproduce asexually. This leads to regional variants that are not, technically at least, new species.

Identification: Plants are 6-60" (15-152 cm) in height, with leafy stems, the lower part of which have long hairs. Upper stems are fuzzy. Stems, leaves and stolons secrete a milky latex when cut. Leaves are alternate, lanceolate to elliptic, smooth and greenish gray on top, hairy and rough below. Leaves are pointed, with sparse, unevenly spaced sharp teeth. Leaves attach directly to stems, sometimes partially clasping the stems. Flowers appear in loosely branched clusters. Each flower is about 1" (2.5 cm) across, with 30 or more florets.

This hawkweed comparison table is an aid to identifying hawkweeds and similar-appearing species.

Online References:

Hieracium canadense at the Plants of the Eloise Butler Wildflower Garden

Hieracium canadense on

Hieracium canadense at the Lady Bird Johnson Wildflower Center

Hieracium canadense on eFloras

References:

Clemants, Steven; Gracie, Carol, Wildflowers in the Field and Forest, Oxford University Press, 2006, p. 162

9/7/2013 · Beech Hill, Dublin, New Hampshire
≈ 15 × 10" (37 × 25 cm)

9/7/2013 · Beech Hill, Dublin, New Hampshire
≈ 5 × 4½" (13 × 11 cm)

6/22/2018 · Tom and Susan’s, Pepperell, Massachusetts
≈ 4½ × 3" (11 × 7.9 cm)

6/22/2018 · Tom and Susan’s, Pepperell, Massachusetts
≈ 7 × 4" (16 × 11 cm)

9/3/2020 · Mitchell Field, Harpswell, Maine
≈ 4 × 6" (10 × 15 cm)

9/29/2013 · Compass Harbor, Acadia National Park, Bar Harbor, Maine
≈ 9 × 6" (22 × 15 cm)

6/14/2017 · J. Harry Rich State Forest, Groton, Massachusetts
≈ 4½ × 6" (11 × 15 cm)

9/18/2009 · Acadia National Park, Bar Harbor, Maine
≈ 3 × 2" (8.4 × 5.6 cm)

9/10/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 7 × 7" (18 × 18 cm)

9/25/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 14 × 9" (35 × 23 cm) ID is uncertain

8/2/2012 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, Massachusetts
≈ 3½ × 3" (9.4 × 8.3 cm) ID is uncertain

9/7/2013 · Beech Hill, Dublin, New Hampshire
≈ 7 × 5" (17 × 12 cm)

6/14/2017 · J. Harry Rich State Forest, Groton, Massachusetts
≈ 7 × 10" (16 × 24 cm)

Hieracium canadense description by Thomas H. Kent, last updated 7 Sep 2020.

6/22/2018 · Tom and Susan’s, Pepperell, Massachusetts
≈ 6 × 4½" (16 × 12 cm)

9/14/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 9 × 13" (23 × 32 cm) ID is uncertain

9/10/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 5" (16 × 13 cm)

9/25/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 6 × 5" (15 × 13 cm) ID is uncertain

6/22/2018 · Tom and Susan’s, Pepperell, Massachusetts
≈ 4 × 5" (11 × 13 cm)

9/7/2013 · Beech Hill, Dublin, New Hampshire
≈ 9 × 7" (21 × 16 cm)

9/10/2010 · Nashua River Rail Trail, Groton Center, Groton, Massachusetts
≈ 9 × 8" (23 × 20 cm)

8/2/2012 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, Massachusetts
≈ 5 × 8" (13 × 19 cm) ID is uncertain

8/2/2012 · Nashua River Rail Trail, near Nashoba Hospital, Ayer, Massachusetts
≈ 6 × 9" (15 × 23 cm) ID is uncertain

9/7/2013 · Beech Hill, Dublin, New Hampshire
≈ 10 × 7" (25 × 16 cm)

9/3/2020 · Mitchell Field, Harpswell, Maine
≈ 7 × 4½" (17 × 12 cm)

9/14/2009 · Near Nashoba Hospital, Ayer, Massachusetts
≈ 14 × 15" (34 × 37 cm) ID is uncertain

9/7/2013 · Beech Hill, Dublin, New Hampshire
≈ 6 × 5" (16 × 12 cm)

9/29/2013 · Compass Harbor, Acadia National Park, Bar Harbor, Maine
≈ 4½ × 4" (12 × 10 cm)

6/14/2017 · J. Harry Rich State Forest, Groton, Massachusetts
≈ 5 × 7" (13 × 18 cm)

6/22/2018 · Tom and Susan’s, Pepperell, Massachusetts
≈ 4½ × 4" (11 × 11 cm)

Range:

About this map...