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• Dichotomous Key
• Asteraceae
• Asteraceae Group 3
• Xanthium
• Xanthium spinosum

Xanthium spinosum — spiny cocklebur

Facts

The origins of spiny cocklebur is not resolved. It may be introduced everywhere north of South America, or it may be native in much of its northern hemisphere distribution. Because of its burs, it probably reached New England mainly as a waste product of the wool-carding industry in the nineteenth century.

Habitat

Anthropogenic (man-made or disturbed habitats)

Characteristics

• Flowers

  Bases of bract appendages

  NA

  Bract cycle number

  • there are three or more cycles of bracts
  • there are two main cycles of bracts
  • there is one main cycle of bracts

  Bract outer side hair type

  the bracts are hairy, with simple hairs on their outer surface

  Bract outer side hairs

  the bracts are hairy on their outer surfaces

  Bract separation

  • at least some flower heads have bracts connected to one another at or near their bases
  • the bracts appear completely unconnected to one another on all flower heads

  Disk flower color

  • NA
  • white

  Disk flower lobe number

  5

  Disk flower number

  21-50

  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 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 papery scales on it

  Flower head platform surface

  the scales are slightly hairy, at least near the top

  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

  • NA
  • the disk is conical across the top

  Flower head shape

  NA

  Flower type in flower heads

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

  Height of flower head base

  8–40 mm

  Inflorescence branching (Solidago)

  NA

  Inflorescence shape

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

  Ovary beak

  there is a 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 profile

  in profile, the ovary is roughly elliptical (widest in the middle, tapering to both ends)

  Ray flower color

  NA

  Ray flower reproductive parts

  NA

  Ray flowers

  NA

  Ray length

  0 mm

  Reproductive system

  the flowers on the plant may have either carpels or stamens, but always in separate flowers

  Style branch number

  there are no obvious branches on the style

  Width of flower head base

  6–8 mm

• Fruits or seeds

  Dispersal unit

  the entire flower head falls off or disperses as a unit

  Number of pappus parts

  NA

  Ovary length in developed fruit

  10–15 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 glandular (translucent) dots or scales
  • 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

  Spines on plant

  there are spines on the plant

  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

  Hairs on upper side of leaf blade

  the upper side of the leaf is fuzzy or hairy

  Leaf arrangement

  alternate: there is one leaf per node along the stem

  Leaf blade base

  the leaf has a distinct 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

  Leaf blade edges

  • the edge of the leaf blade has no teeth or lobes
  • the edge of the leaf blade has teeth

  Leaf blade hairs

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

  Leaf blade length

  40–120 mm

  Leaf blade shape

  the leaf blade is lanceolate (lance-shaped; widest below the middle and tapering at both ends)

  Leaf blade tip

  • the tip of the leaf blade is acuminate (tapers to a long, thin point)
  • the tip of the leaf blade is acute (sharply pointed)

  Leaf blade veins

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

  Leaf blade width

  10–50 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

  Leaf stalk length

  1–25 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 leaves are simple (lobed or unlobed but not separated into leaflets

• Place

  Habitat

  terrestrial

  New England state

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

  Specific habitat

  man-made or disturbed habitats

• Stem, shoot, branch

  Leaves on stem

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

  Stem internode hair direction

  the hairs are pressed flat against the plant, pointing either towards the plant's tip or towards it's base

  Stem internode hair type

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

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