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- Hieracium pilosella
Hieracium pilosella — mouse-ear hawkweed
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Facts
Mouse-ear hawkweed is native to Europe and introduced to eastern and northwestern North America, where it is considered a noxious weed in some states. It reproduces both clonally by stolons, and by seed, and establishes well in low-nutrient and overgrazed situations.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
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Characteristics
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Leaf type
- leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaf arrangement
-
- alternate: there is one leaf per node along the stem
- basal: the leaves are growing only at the base of the plant
- Leaf blade edges
- the edge of the leaf blade has no teeth or lobes
- Flower type in flower heads
- the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray
- Ray flower color
- yellow
- Tuft or plume on fruit
- at least a part of the plume is made up of fine bristles
- Spines on plant
- the plant has no spines
- Leaf blade length
- 10–75 mm
- Disk flower number
- 0
-
Flowers
- Bases of bract appendages
- NA
- Bract outer side hairs
- the bracts are hairy on their outer surfaces
- Bract tip shape
-
- the tips of the bracts acute (have a sharp point)
- the tips of the bracts are acuminate (tapered to a narrow point)
- Disk flower color
- NA
- Disk flower lobe number
- 0
- Disk flower number
- 0
- Disk flower proportions
- NA
- Disk flower reproductive parts
- NA
- Disk flower shape
- NA
- Flower head number
- each flowering stem has only one to three flower heads on it
- Flower head outer flowers
- at the outer edge of the flower head, each flower has a single enlarged lobe or strap
- Flower head platform
- the base has no bristles or papery scales
- Flower head platform surface
- NA
- Flower head profile
- the disk is flat or nearly flat across the top
- Flower head shape
- the flower head is hemispherical (like the bottom half of a sphere)
- Flower type in flower heads
- the flower head has ray flowers only, meaning all of the individual flowers of the flower head have a strap-shaped ray, which may or may not have teeth at the very tip of the ray
- Height of flower head base
- 7.5–10 mm
- Inflorescence branching (Solidago)
- NA
- Number of bracts at flower head base
- 20–34
- Ovary beak
- there is no beak on the ovary
- Ovary cross-section
- the ovary has five or more corners in cross-section
- Ovary hair type
- the ovary has no hairs on it
- Ovary hairs
- the ovary has no hairs on it
- Ovary lines or ribs
-
- there are seven to nine ribs visible on the ovary
- there are ten or more ribs visible on the ovary
- Peduncle hair type
- the hairs on the peduncles are branched
- Peduncle hairs
- the peduncles are hairy
- Ray flower color
- yellow
- Ray flower reproductive parts
- the ray flowers have both carpels and stamens
- Ray flowers
- more than 50
- Ray length
- 8–13 mm
- Reproductive system
- all the flowers on the plant contain both carpels and stamens
- Scale tip
- NA
- Smaller bracts at base of bracts
- there is a cycle of much smaller bracts outside the cycle of larger and longer bracts
- Style branch number
- there are no obvious branches on the style
-
Fruits or seeds
- Dispersal unit
- the seeds fall off or are dispersed separately from one another
- Number of pappus parts
- 11 or more
- Ovary beak length
- 0 mm
- Ovary length in developed fruit
- 1.5–2 mm
- Ovary width in developed fruit
- 0.3–0.5 mm
- Seed hair tuft color
- the pappus hairs are white or off-white
- Seed hair tuft details
- the pappus hairs are hooked or barbed
- Seed hair tuft length
- 4–5 mm
- Seed hairs uniform
- all the pappus hairs are approximately the same length
- Seed tuft scale number
- 0
- Seed tuft type
- the pappus is made of very fine hairs or bristles
- Top of disk flower ovary
- NA
- Tuft or plume on fruit
- at least a part of the plume is made up of fine bristles
-
Glands or sap
- Leaf blade glands
- the leaf blades have no glandular (translucent) dots or scales
- Sap
- the sap is milky and opaque, and may be white or colored
-
Growth form
- Growth form
- the plant has one or more free-standing stems
- Horizontal rooting stem
- there are stolons on some plants
- Plant lifespan
- the plant is perennial, it shows evidence of previous year's leaves, stems or stem bases
- Spines on plant
- the plant has no spines
- Underground organs
- there is a thickened taproot on the plant
-
Leaves
- Final leaf segment length (compound lvs only)
- 0 mm
- Final leaf segment width (compound lvs only)
- 0 mm
- Hairs on underside of leaf blade
-
- the underside of the leaf is fuzzy or hairy
- the underside of the leaf is not hairy, or has very few hairs
- Hairs on upper side of leaf blade
-
- the upper side of the leaf is fuzzy or hairy
- the upper side of the leaf is not hairy, or has very few hairs
- Leaf arrangement
-
- alternate: there is one leaf per node along the stem
- basal: the leaves are growing only at the base of the plant
- Leaf blade base
-
- the leaf has a distinct petiole
- the leaf has no petiole
- Leaf blade base shape
- the base of the leaf blade is cuneate (wedge-shaped, tapers to the base with relatively straight, converging edges), or narrow
- Leaf blade bloom
-
- the underside of the leaf has no noticeable bloom
- there is a noticeable powdery or waxy bloom on the underside of the leaf
- Leaf blade edges
- the edge of the leaf blade has no teeth or lobes
- Leaf blade hairs
-
- the leaf blade has branched hairs
- the leaf blade has simple hairs with no glands, and not tangled or wooly
- Leaf blade length
- 10–75 mm
- Leaf blade shape
-
- the leaf blade is elliptic (widest near the middle and tapering at both ends)
- the leaf blade is oblanceolate (lance-shaped, but with the widest point above the middle of the leaf blade)
- Leaf blade surface colors
- there is no noticeable color variation on the upper surface of the leaf
- Leaf blade tip
-
- the tip of the leaf blade is acute (sharply pointed)
- the tip of the leaf blade is obtuse (bluntly pointed)
- Leaf blade width
- 5–18 mm
- Leaf disposition
- the lower leaves are larger, toothier, and/or on longer stalks than the upper leaves
- Leaf spines
- there are no spines on the leaf edges
- Leaf stalk
-
- the leaves have leaf stalks
- the leaves have no leaf stalks, but attach directly to the stem
- Leaf tip extension
- NA
- Leaf type
- leaves are simple (i.e., lobed or unlobed but not separated into leaflets)
- Leaflet number
- 0
- Specific leaf type
- the leaves are simple (i.e., lobed or unlobed but not separated into leaflets
- Teeth per side of leaf blade
- 0
-
Place
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- man-made or disturbed habitats
- meadows or fields
-
Scent
- Plant odor
- the plant does not have much of an odor
-
Stem, shoot, branch
- Flowering stem cross-section
- the flowering stem is circular, or with lots of small angles
- Leaves on stem
- the flowering stem has no leaves above the base
- Stem bloom
-
- the stem has a powdery or waxy film on it that can be rubbed away
- there is no powdery or waxy film on the stem
- Stem internode hair direction
- the hairs point mostly upwards to outwards
- Stem internode hair length
- 1–3 mm
- Stem internode hair type
-
- at least some of the hairs on the stem are branched
- at least some of the hairs on the stem have glands
- Stem internode hairs
- the stem has hairs between the nodes
- Stem wings
- the stem does not have wings on it
Wetland status
Not classified
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- not applicable (S-rank: SNA)
From Flora Novae Angliae dichotomous key
10. Hieracium pilosella L. E
mouse-ear hawkweed. Hieracium pilosella L. var. niveum Muell.-Arg.; Pilosella officinarum F.W. Schultz & Schultz-Bip. • CT, MA, ME, NH, RI, VT. Open areas such as lawns, fields, and roadsides.
Native to North America?
No
Sometimes confused with
- Hieracium flagellare:
- capitulescence with mostly 2–4 capitula and involucres mostly 10–13 mm tall (vs. H. pilosella, with the capitulescence with mostly 1 or 2 capitula and involucres mostly 7.5–9 mm tall).
Synonyms
- Hieracium pilosella L. var. niveum Muell.-Arg.
- Pilosella officinarum F.W. Schultz & Schultz-Bip.