Weed Seed: Woolly distaff thistle (Carthamus lanatus)

Family

Asteraceae

Distribution in Canada

Found in BC

Duration of life cycle

Annual

Seed/Fruit type

Achene - a one-seeded, dry fruit

Seed identification features

Size

  • length: 5.0–5.5 mm
  • width: 3.0–3.5 mm

Shape

  • in outline: obovate (upside-down and egg-shaped)
  • in cross-section: angled

Surface texture

  • slightly shiny
  • roughened with ridges and oval pits

Colour

  • bone coloured, becoming medium brown within pits on surface

Other structures

  • pappus at top of achene
    • may be persistent on processed seed
    • made up of short, flattened bristles (up to 7.5 mm)
    • usually pale, but may be brown coloured
  • top peg is short, within a shallow depression surrounded by several projecting teeth

Similar species

Distaff thistle (Carthamus dentatus)

  • not known if found in North America
  • similar to woolly distaff thistle in size, obovate shape, pale colour and flattened pappus bristles
  • achenes are not rough, and are duller than achenes of woolly distaff thistle
  • achenes have brown band at top (woolly distaff thistle lacks this band)

Safflower (Carthamus tinctorius)

  • found in BC, AB, and the western United States
  • obovate shape, pale colour, glossy surface with brownish pits
  • achenes are up to 2.0 mm longer than woolly distaff achenes
  • pappus rarely persists
  • pappus is made of thinner bristles than woolly distaff thistle

Photos

Photo - Woolly distaff thistle (Carthamus lanatus) achene without pappus
Woolly distaff thistle (Carthamus lanatus) achene without pappus
Photo - Woolly distaff thistle (Carthamus lanatus) achene with pappus
Woolly distaff thistle (Carthamus lanatus) achene with pappus
Photo - Woolly distaff thistle (Carthamus lanatus) achene (top-down view showing peg)
Woolly distaff thistle (Carthamus lanatus) achene (top-down view showing peg)
Photo - Woolly distaff thistle (Carthamus lanatus) achenes
Woolly distaff thistle (Carthamus lanatus) achenes

Similar species

Photo - Similar species: Distaff thistle (Carthamus dentatus) achene
Similar species: Distaff thistle (Carthamus dentatus) achene
Photo - Similar species: Safflower (Carthamus tinctorius) achene
Similar species: Safflower (Carthamus tinctorius) achene
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