FloraFinder.org
Home   About Us   Want to Help?   FAQ  
Searching   Image Use Biblio

Hieracium

 

Hawkweed

KingdomPlantaePlants, but not fungi, lichens, or algae (from Stearn’s Botanical Latin)
SubkingdomTracheobiontaVascular plants—plants with a “circulatory system” for delivering water and nutrients
DivisionMagnoliophytaFlowering plants, also known as angiosperms
ClassMagnoliopsidaDicotyledons—plants with two initial seed leaves
SubclassAsteridaeA large class that encompasses asters
OrderAsteralesFlowering plants with a central disk flower and surrounding petals, like daisies
FamilyAsteraceaeThe aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
GenusHieraciumFrom Greek hierakion, “a hawk,” from Pliny’s belief that hawks strengthened their eyesight by eating these plants

About plant names...

Some hawkweeds are European imports, originally intended for gardens, now escaped and widespread throughout North America. Others are natives. Especially in the Pacific northwest, some of the imports are considered invasives.

Pliny the Elder believed that hawks fed on hawkweeds to improve their otherwise dull eyesight. This results in both the common and genus names. Hieracium derives from Greek hierakion, or “hawk.” Hawks in fact have incredibly precise vision. There is no evidence that they pay any attention to these plants, nor, as far as I was able to find, is there anything in hawkweeds that might improve vision.

Hawkweeds are apomictic, reproducing asexually—new plants are near-perfect genetic clones of their parents. Most plants, by contrast, reproduce sexually, so that offspring reflect a mixture of traits from both parents. Since hawkweeds are asexual, they change more slowly than other species, but other agents of evolution, such as mutation, still result in changes. These more subtle changes produce microspecies, sometimes in numerous variations, bedevilling those of us with a penchant for classifying plants. Not to mention those of us struggling to invent the science of genetics:

Identification: Hawkweeds typically consist of a basal rosette of leaves, with long stems that are sometimes bare or sometimes contain alternate leaves. Leaves vary a lot in shape. Stems and leaves are usually hairy, sometimes very hairy. When cut or broken, hawkweed stems, leaves, and stolons produce a bitter milky sap. Hawkweeds form patches or colonies, spreading by stolons (above-ground roots) or by seed. Flowers usually occur in clusters and are composed of ray flowers that have squared-off tips and several serrations at the end of each ray. Most are yellow; one species is orange. Flowers are replaced by pappi, round balls containing seeds like those of dandelions; sometimes the pappi are shaped more like an old-style shaving brush. Each seed has its own parachute for wind dispersal.

Online References:

Hieracium on msuextension.org (PDF)

Hieracium on www.jeffpippen.com

Hieracium on www.eddmaps.org Key to Identification of Invasive and Native Hawkweeds (Hieracium spp.) in the Pacific Northwest (PDF)

Here are some hawkweeds and similar-appearing species:

 

Hieracium (Hawkweed)

Yellow Hawkweed (Hieracium) · 8/2/2008 · Bar Harbor, ME
≈ 3½ × 2½" (9.8 × 6.6 cm) Species not yet identified

Hieracium (Hawkweed)

Orange Hawkweed (Hieracium aurantiacum) · 9/29/2012 · Franconia Notch Area, NH
≈ 3½ × 3" (9.2 × 7.9 cm)

Hieracium (Hawkweed)

Canada Hawkweed (Hieracium canadense) · 9/29/2013 · Compass Harbor, Acadia National Park, Bar Harbor, ME
≈ 5 × 5" (12 × 13 cm)

Hieracium (Hawkweed)

Gronovius’ Hawkweed (Hieracium gronovii) · 7/31/2012 · Bemis Rd Conservation Area, Pepperell, MA
≈ 4 × 6" (10 × 15 cm) ID is uncertain

 
Hieracium aurantiacum

Hieracium caespitosum

Hieracium canadense
Common Name

Orange Hawkweed

Field Hawkweed

Canada Hawkweed
Plant Plants are 8-24" (20-60 cm) high. Leaves and stems produce a milky latex when broken. Plants consist of a basal rosette with 3-8 or more leaves, and many tall, thin relatively bare flower stems 10-36" (25-91 cm) high. Stems, leaves, and stolons exude a milky latex when cut. Stems have dense hairs ¹/₃₂-⅛" (1-4 mm) long, softer toward the bottom, stiffer toward the top. 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.
Flowers Bright orange (the only orange hawkweed), with paler orange centers, in small clusters atop tall stems. Flower rays have squared-off, serrated tips. Flowers are ½-¾" (1.3-1.9 cm) around. Stems are topped with a flat- or umbrella-shaped cluster of 5-30 yellow flowers. Flowers appear from May to August, and are ½-1" (1.3-2.5 cm) across. In loosely branched clusters. Each flower is about 1" (2.5 cm) across, with 30 or more florets.
Leaves Leaves are mostly at the bottom, spatula-shaped and very fuzzy, up to 5" (12 cm) long. Basal leaves are 2-10" (5-25 cm) long and ½-1¼" (1.3-3.2 cm) wide. They are variable in appearence, oblong lanceolate to elliptic in shape, with blunt or pointed tips, sometimes toothed. 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.
Range/ Zones

Habitats Meadows, grasslands, rangelands, pastures, lawns Fields, disturbed areas, roadsides, spare woodlands. Fields, sand plains, roadsides, forest edges, cliffs, grasslands, shorelines.
Type Wild Wild Wild
Occurrence Common Common Common

 

 
Hieracium gronovii

Hieracium murorum

Hieracium paniculatum
Common Name

Gronovius’ Hawkweed

Wall Hawkweed

Panicled Hawkweed
Plant 12-18" (30-45 cm) in height, rarely up to 31" (80 cm), with hairy stems. Stems, leaves, and stolons secrete a milky sap when cut. Plants are 10-24" (25-60 cm) in height, with hairy stems. 3-6 leaves appear at the base of the plant, sometimes with two or three more on the stems. From a base on the ground that survives the winter, this hawkweed produces stems up to 3' (1 m) high, with sparse leaves and hairs on the lower stem and leaves that are ⅛-⅜" (3-10 mm) long.
Flowers Flower heads have 25-50 flowers, and take the form of thyrse—a raceme composed of several branching cymes. Each flower is yellow, ½-1" (1.3-2.5 cm) across, with 20-40 rays. (An otherwise similar species, Hieracium scabrum, has 40-100 rays.) Flowers appear Jul to Oct. Flower heads appear as 5-8 corymbs. Flowers are yellow, with 30-50 or more florets, about ½" (1.3 cm) in size. They flower in June. The top portion of the plant branches in a delicate tracery of sinuous, hairless, thin-branched flowering heads. Each of the dozens of flowers are less than ½" (1.5 cm) in length, with less than 20 florets.
Leaves Most of the leaves are a basal rosette of spatula-shaped leaves up to 3½-4" (9-10 cm) × 1" (2.6 cm). Leaves are alternate, usually unlobed and toothless, and oblanceolate, obovate, elliptic, or spatulate. Elliptic, 1¾-4" (5-11 cm) × ⅞-1¾" (2.5-4.5 cm), sometimes mottled with purple. Unusual in shape, wide at the base, with large, forward-pointing teeth that fall somewhere between the designation of “tooth” vs. “lobe.” Leaves are narrow, with irregularly toothed margins and whitish undersides.
Range/ Zones

Habitats Dry prairies, savannas, fields, or roadsides; openings in beech-maple forests; sandy soils. Disturbed areas, rocky areas, fields, thickets, lawns. Dry to medium wet decidious forests and woodlands, trail edges.
Type Wild Wild Wild
Occurrence Fairly common; rare in Maine Uncommon Fairly common

 

 
Hieracium pilosella

Lapsana communis
Common Name

Mouse Ear

Nipplewort
Plant Exceptionally hairy, even for hawkweeds, especially the leaves, whose undersides are soft enough to have earned the name “mouse ears.” Upper leaf surfaces are also covered with coarser long white hairs. Plants are 6-60" (15-152 cm) in height, either hairy or hairless. A stiff major stem is often reddish and somewhat ridged.
Flowers Solitary yellow flowers appear 1¾-20" (5-50 cm) above the base of leaves, on stems with stiff dark hairs and no leaves, each flower up to 1" (2.5 cm) across. They appear Jun-Sep. Panicles of 5-25, rarely as high as 100, each flower ¼-½" (6.3-12 mm) across, with 18-20 pale yellow rays. Paler than hawkweed flowers, and significantly different at close range. Appear Apr-Sep.
Leaves Plants have a basal rosette of leaves which are unlobed, elliptic, pointed to blunt, and ⅜-4" (1-10 cm) × ⅛-¾" (5-20 mm). Leaves have a prominent white midvein. Oval or round, ⅜-6" (1-15 cm) × ⅜-2½" (1-7 cm). Each leaf has a large roughly triangular (deltate) lobe at the end, often with two smaller side lobes at the base that vaguely resemble nipples. Lower leaves also have a long petiole that is slightly winged and hairy.
Range/ Zones

Habitats Lawns, pastures, hayfields, roadsides. Disturbed soil, roadsides, woods, alkaline soils, in full or partial sun.
Type Wild Wild
Occurrence Common to invasive Uncommon

 

Hieracium description by Thomas H. Kent, last updated 11 Oct 2013.

© FloraFinder.org. All rights reserved.