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• Petasites hybridus

Petasites hybridus — butterbur sweet-coltsfoot

Facts

Butterbur sweet-coltsfoot is native to Europe and an occasional visitor to North America. This distinctive wetland plant has unmistakable flowers as well as giant rhubarb-like leaves up to three feet across. Clinical trials have shown that extracts of butterbur root are effective in reducing frequency and severity of migraine.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields, shores of rivers or lakes

Characteristics

• Flowers

  Bract color

  the bracts are colored, or at least tinged with, pink, red or purple

  Bract cycle number

  • there are two main cycles of bracts
  • there is one main cycle of bracts

  Bract keels

  there is one distinct keel on the bracts

  Bract margins

  there are few or no fine hairs along the bract margins

  Bract outer side hair type

  the bracts are not hairy on their outer surface

  Bract outer side hairs

  the bracts are not hairy on their outer surfaces

  Bract shape

  • the main bracts are oblanceolate (widest near the tip, but otherwise narrow and tapering)
  • the main bracts are oblong (roughly rectangular but rounded at the ends)

  Bract spines

  the bracts have no spines

  Bract tip extension appearance

  NA

  Bract tip extension edge

  there are no projections from the bract tips

  Bract tip orientation

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

  Bract tip shape

  • the tips of the bracts acute (have a sharp point)
  • the tips of the bracts are obtuse (have a blunt point)

  Bract width

  5–16

  Bracts

  the bracts in separate cycles are similar or gradually changing from the outer to inner cycles

  Disk flower color

  blue to purple

  Disk flower lobe number

  5

  Disk flower number

  • 11-20
  • more than 50

  Disk flower reproductive parts

  the disk flower has either only pollen- or only seed-producing parts

  Disk flower shape

  the disk flower is tube-shaped (cylindrical), or gradually widening like a funnel

  Flower head number

  • each flowering stem has four or more flower heads on it
  • each flowering stem has only one to three flower heads on it

  Flower head outer flowers

  at the outer edge of the flower head, the flowers have no enlarged lobe or strap, and are of similar size as those in the center of the disk

  Flower head platform

  the base has no bristles or papery scales

  Flower head platform surface

  NA

  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

  • NA
  • the flower head is shaped like a cone with the point up

  Flower type in flower heads

  the flower head has disk flowers only, and lacks the strap-shaped flowers

  Height of flower head base

  2.5–8.5 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

  the inflorescence is not flat-topped but appears rounded, with some flower heads distinctly higher than others

  Inflorescence stem

  the stem of the inflorescence is not hairy

  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 four to six lines or ribs visible on the ovary
  • there are seven to nine ribs visible on the ovary
  • there are ten or more ribs visible on the ovary

  Ovary profile

  in profile, the ovary is very narrow

  Peduncle hair type

  the hairs on the peduncles appear tangled or woolly

  Peduncle hairs

  the peduncles are hairy

  Ray flower color

  NA

  Ray flower reproductive parts

  NA

  Ray flowers

  0

  Ray length

  0 mm

  Reproductive system

  all the flowers on some plants have carpels, while all the flowers on other plants have 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

• Fruits or seeds

  Number of pappus parts

  1

  Ovary length in developed fruit

  Up to 3 mm

  Seed hair tuft details

  the pappus hairs are smooth and plain

  Seed hair tuft tips

  the pappus hairs are slender

  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

  Sap

  the sap is clear and watery

• Growth form

  Growth form

  the plant has one or more free-standing stems

  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

  Hairs on upper side of leaf blade

  the upper side of the leaf is not hairy, or has very few hairs

  Leaf arrangement

  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 is cordate (heart-shaped) or sagittate (arrow-shaped)

  Leaf blade bloom

  the underside of the leaf has no noticeable bloom

  Leaf blade edges

  the edge of the leaf blade has teeth

  Leaf blade hairs

  the leaf blade has tangled or woolly-looking hairs

  Leaf blade length

  100–300 mm

  Leaf blade shape

  • NA
  • the leaf blade is cordate (heart-shaped with backward-facing rounded lobes), or sagittate (arrow-shaped with backward-facing pointed lobes)
  • the leaf blade is orbicular (roughly circular, as wide as long)

  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 rounded, with no point

  Leaf blade veins

  NA

  Leaf blade width

  100–300 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 tufts in axils

  there are no clusters of smaller leaves

  Leaf type

  leaves are simple (i.e., lobed or unlobed but not separated into leaflets)

  Leaflet number

  0

  Specific leaf type

  the leaf has lobes that radiate from the base, somewhat like a hand

• Place

  Habitat

  • terrestrial
  • wetlands

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont

  Specific habitat

  • man-made or disturbed habitats
  • meadows or fields
  • shores of rivers or lakes

• 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 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

  Stem internode hairs

  the stem has hairs between the nodes

Wetland status

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae