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• Petasites japonicus

Petasites japonicus — Japanese sweet-coltsfoot

Facts

Japanese sweet-coltsfoot is native to China, Japan, and Korea, and is sometimes used as a garden ornamental for wet soils. In Japan, the leaf stalks (petioles) are eaten as a vegetable. This is a very occasional escapee from cultivation in New England, having been collected only in Maine.

Habitat

Anthropogenic (man-made or disturbed habitats)

Characteristics

• Flowers

  Bract color

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

  Bract cycle number

  there are two main cycles of bracts

  Bract keels

  the bracts do not have keels

  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 oblong (roughly rectangular but rounded at the ends)

  Bract spines

  the bracts have no spines

  Bract tip color

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

  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 are obtuse (have a blunt point)

  Bracts

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

  Disk flower color

  white

  Disk flower lobe number

  5

  Disk flower number

  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

  Flower head outer flowers

  • at the outer edge of the flower head, each flower has a single enlarged lobe or strap
  • 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

  Flower head shape

  the sides of the flower head are roughly parallel, like a cylinder

  Flower type in flower heads

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

  Flowering stem width

  7–10 mm

  Height of flower head base

  6 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

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

  Inflorescence stem

  hairs are present on the stem of the inflorescence

  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 oblong (roughly rectangular but rounded at the ends)

  Peduncle hairs

  the peduncles are hairy

  Peduncle orientation

  the flower heads are held upright, or slightly angled outwards

  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

  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

  7–10 mm

• Fruits or seeds

  Number of pappus parts

  1

  Ovary length in developed fruit

  3.5 mm

  Seed hair tuft color

  the pappus hairs are white or off-white

  Seed hair tuft length

  12 mm

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

  Leaf arrangement

  the leaves are growing only at the base of the plant (basal)

  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 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

  150–300 mm

  Leaf blade shape

  • 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

  150–300 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 (lobed or unlobed but not separated into leaflets)

  Leaflet number

  0

  Specific leaf type

  the leaves are simple (lobed or unlobed but not separated into leaflets

• Place

  Habitat

  terrestrial

  New England state

  Maine

  Specific habitat

  man-made or disturbed habitats

• 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

  the hairs on the stem are plain, without glands or branches, and not tangled

  Stem internode hairs

  the stem has hairs between the nodes

  Stem wings

  the stem does not have wings on it

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae