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• Carduus acanthoides

Carduus acanthoides — spiny plumeless-thistle

Facts

This non-native species is considered a noxious weed and prohibited in many states across the country. It is a very spiny species, and spreads rapidly by producing many thousands of seeds per plant.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields

Characteristics

• Flowers

  Bases of bract appendages

  NA

  Bract cycle number

  there are three or more cycles of bracts

  Bract margins

  there are fine hairs along the bract margins

  Bract outer side hair type

  • the bracts are hairy, with simple hairs on their outer surface
  • the bracts are not hairy on their outer surface

  Bract shape

  • the main bracts are lanceolate (widest above the base, then taper narrowly towards the tip)
  • the main bracts are linear (long and very narrow)

  Bract spines

  there is just one simple spine at the tip of the bract

  Bract tip extension edge

  there are 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)

  Bract width

  1–2

  Disk flower color

  • blue to purple
  • white

  Disk flower lobe number

  5

  Disk flower reproductive parts

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

  Disk flower shape

  • the disk flower is abruptly widened at some point below the lobes
  • the disk flower is tube-shaped (cylindrical), or gradually widening like a funnel

  Disk width

  15–25 mm

  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 fine, short hairs on it

  Flower head platform surface

  NA

  Flower head position

  • each of the flower heads is separate on its own peduncle (stalk), not clustered in groups
  • some or all the flower heads are grouped in clusters of two or more

  Flower head profile

  • the disk is conical across the top
  • 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)

  Flower head width

  18–25 mm

  Flower type in flower heads

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

  Height of flower head base

  14–20 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

  the inflorescence is flat-topped in profile

  Ovary attachment

  • the ovary is attached at or near the base
  • the ovary is attached at the side near the base, rather than at the base

  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 profile

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

  Ovary surface

  the ovary surface has no points, bumps or wrinkles, though it may have lines, ribs or wings

  Peduncle length

  Up to 100 mm

  Ray flower color

  NA

  Ray flower reproductive parts

  NA

  Ray flowers

  0

  Ray length

  0 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 no smaller, outer cycle of bracts

  Width of flower head base

  10–25 mm

• Fruits or seeds

  Number of pappus parts

  11 or more

  Ovary length in developed fruit

  2.5–3 mm

  Seed hair tuft bases

  the pappus hairs are attached to one another near the base

  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

  11–13 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 clear and watery

• Growth form

  Growth form

  the plant has one or more free-standing stems

  Plant lifespan

  • the plant is annual, it lacks evidence of previous years' growth
  • the plant is biennial, it appears as either first year (non-reproductive) plants or second year plants with flowers or fruit

  Spines on plant

  there are spines on the plant

  Underground organs

  there is a thickened taproot on the plant

• 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

  alternate: there is one leaf per node along the stem

  Leaf blade base

  • the leaf has a distinct petiole
  • the leaf has no petiole

  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 hairs

  • the leaf blade has simple hairs with no glands, and not tangled or wooly
  • the leaf blade has tangled or woolly-looking hairs

  Leaf blade length

  100–300 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 veins

  the leaf blade has one main vein running from the base towards the tip

  Leaf blade width

  20–80 mm

  Leaf disposition

  • the leaves are nearly similar in size, prominence of teeth, and length of stalks throughout the stem
  • the lower leaves are larger, toothier, and/or on longer stalks than the upper leaves

  Leaf spines

  there are spines along 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 simple (lobed or unlobed but not separated into leaflets)

  Leaflet number

  0

  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

• Place

  Habitat

  terrestrial

  New England state

  • Connecticut
  • Maine
  • Massachusetts
  • 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

  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

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

  Stem internode hairs

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

  Stem wings

  the stem has wings on it that run down the stem from the leaf nodes

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae