Family
Asteraceae
Distribution in Canada
Found in BC, AB, MB, ON, QC, NB, NS
Duration of life cycle
Annual or biennial
Seed/Fruit type
Achene - a one-seeded, dry fruit
Seed identification features
Size
- length: 6.5–7.5 mm
- width: 2.0–2.5 mm
- thickness: 1.7 mm
Shape
- in outline: oblong (oval with straight sides)
- in cross-section: slightly curved, oval
Surface texture
- smooth with a sheen
- slight cross-wise wrinkles under magnification
Colour
- overall dark brown, with occasional golden streaks
- golden-coloured ring at top of seed
- middle of seed can be greenish-brown
- occasionally, seeds have large, light-brown patches
Other structures
- achene has two ends
- top is a lobed peg, ringed by thin rim (a remnant of the floral parts)
- base is a small slit (seen only under magnification)
- a long white pappus may be present on freshly harvested seeds
Similar species
Nodding thistle (Carduus nutans)
- found across Canada (except in NU, YT, NT) and the United States (except in Florida)
- one-half the length and width of blessed milkthistle
- similar to blessed milkthistle in shape, satiny surface texture, and the presence of prominent peg at top of achene
- top peg is not lobed, and is a lighter colour than blessed milkthistle
Photos
Similar species
