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• Dichotomous Key
• Asteraceae
• Asteraceae Group 4
• Achillea
• Achillea millefolium

Achillea millefolium — common yarrow

Facts

Common yarrow has been used as a medicine, fumigant, and insecticide. It is known in traditional medicine for its ability to stop bleeding, and indeed, it contains an alkaloid called achileine that enhances blood clotting.

Habitat

Alpine or subalpine zones, anthropogenic (man-made or disturbed habitats), cliffs, balds, or ledges, meadows and fields, mountain summits and plateaus, ridges or ledges, shores of rivers or lakes

Characteristics

• Flowers

  Bases of bract appendages

  NA

  Bract color

  the bracts are not colored or tinged with pink, red or purple

  Bract cycle number

  there are three or more cycles of bracts

  Bract outer side hair type

  the bracts are hairy on their outer surfaces, with curled, tangled, matted, or woolly hairs

  Bract outer side hairs

  the bracts are hairy on their outer surfaces

  Bract shape

  • the main bracts are lanceolate (widest above the base, then taper narrowly towards the tip)
  • the main bracts are ovate (egg-shaped)

  Bract spines

  the bracts have no spines

  Bract tip color

  the tips are a different color from the center of the bract

  Bract tip orientation

  the bracts are pressed against the plant, or spreading out at the tips

  Bracts

  there are at least two distinct forms of bracts in different cycles

  Disk flower color

  white

  Disk flower lobe number

  5

  Disk flower number

  • 11-20
  • 6-10

  Disk flower reproductive parts

  the disk flower has both pollen- and seed-producing parts

  Disk width

  2–4 mm

  Flower head number

  each flowering stem has four or more 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 papery scales on it

  Flower head position

  some or all the flower heads are grouped in clusters of two or more

  Flower head profile

  • the disk is flat or nearly flat across the top
  • the disk is rounded across the top

  Flower head shape

  • the flower head is hemispherical (like the bottom half of a sphere)
  • the sides of the flower head are roughly parallel, like a cylinder

  Flower type in flower heads

  the flower head has tubular disk flowers in the center and ray flowers, these often strap-shaped, around the periphery

  Height of flower head base

  4–5 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

  the inflorescence is flat-topped in profile

  Inflorescence stem

  hairs are present on the stem of the inflorescence

  Number of bracts at flower head base

  20–30

  Ovary cross-section

  the ovary is compressed (flattened)

  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 three lines or ribs visible on the ovary
  • there are two lines or ribs visible on the ovary

  Ovary profile

  • in profile, the ovary is oblong (roughly rectangular but rounded at the ends)
  • in profile, the ovary is roughly egg-shaped, but widest above the middle

  Peduncle orientation

  the flower heads are held upright, or slightly angled outwards

  Ray flower color

  • pink to red
  • white

  Ray flower reproductive parts

  the ray flowers have carpels or stamens, but not both

  Ray flowers

  • 1-5
  • 6-10

  Ray length

  1–4 mm

  Reproductive system

  some of the flowers on the plant have only carpels or stamens, while others have both carpels and stamens

  Smaller bracts at base of bracts

  there is no smaller, outer cycle of bracts

  Style branch number

  the style has two branches

  Style branches

  the style branch is wider at the tip and has a flattened end, or the style branches are wider at the tips and have flattened ends

  Width of flower head base

  2–5 mm

• Fruits or seeds

  Number of pappus parts

  0

  Ovary length in developed fruit

  1–2 mm

  Seed hair tuft bases

  NA

  Seed hair tuft color

  NA

  Seed hair tuft details

  NA

  Seed hair tuft length

  0 mm

  Seed hair tuft tips

  NA

  Seed hairs uniform

  NA

  Seed tuft scale number

  0

  Seed tuft type

  there is no pappus on the ovary

  Top of disk flower ovary

  NA

  Tuft or plume on fruit

  there is no plume, or the plume is made up of scales, awns, a crown, or a rim

• Glands or sap

  Leaf blade glands

  the leaf blades have no glandular (translucent) dots or scales

  Sap

  the sap is clear and watery

• Growth form

  Growth form

  the plant has one or more free-standing stems

  Horizontal rooting stem

  • there are no stolons
  • 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

  the plant has a rhizome (a horizontal underground stem with roots growing from it)

• Leaves

  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

  Leaf blade base

  • the leaf has a distinct petiole
  • the leaf has no petiole
  • the leaf has no petiole and at the base it clasps the stem, or goes all the way around the stem so the stem appears to pierce the leaf

  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

  Leaf blade edges

  the edge of the leaf blade has lobes, or it has both teeth and lobes

  Leaf blade flatness

  NA

  Leaf blade hairs

  the leaf blade has simple hairs with no glands, and not tangled or wooly

  Leaf blade length

  30–350 mm

  Leaf blade shape

  • the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
  • the leaf blade is linear (very narrow with more or less parallel sides)

  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)

  Leaf blade width

  5–35 mm

  Leaf disposition

  the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem

  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 stalk length

  At least 0 mm

  Leaf tip extension

  NA

  Leaf type

  • leaves are compound (made up of two or more discrete leaflets)
  • leaves are simple (i.e., lobed or unlobed but not separated into leaflets)

  Leaflet number

  At least 15

  Specific leaf type

  • the leaf has a row of two or more lobes on each side of the central axis
  • the leaf has a row of two or more lobes on each side of the central axis, and each lobe itself has rows of lobes on each side of the lobe's central axis
  • the leaf has lobes that themselves have lobes, and these secondary lobes also have lobes; there may be more than three levels of lobes
  • the leaf is compound, there are two or more discrete leaflets

  Teeth per side of leaf blade

  0

• Place

  Habitat

  terrestrial

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont

  Specific habitat

  • alpine or subalpine zones
  • cliffs, balds, or ledges
  • man-made or disturbed habitats
  • meadows or fields
  • mountain summits and plateaus
  • ridges or ledges
  • shores of rivers or lakes

• Scent

  Plant odor

  the plant has a pleasant odor, such as licorice, fruit or resin

• Stem, shoot, branch

  Flowering stem cross-section

  the flowering stem is circular, or with lots of small angles

  Leaves on stem

  there is at least one full leaf above the base of the flowering stem

  Stem bloom

  there is no powdery or waxy film on the stem

  Stem internode hair direction

  the hairs point mostly upwards to outwards

  Stem internode hair type

  • at least some of the hairs on the stem are tangled, matted or woolly
  • the stem has no hairs between the nodes

  Stem internode hairs

  • the stem has hairs between the nodes
  • the stem has no hairs between the nodes

  Stem wings

  the stem does not have wings on it

Wetland status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae