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Hairy Beggarticks🌼
Bidens pilosa
コセンダングサ
An annual known as a "hitchhiker weed" for its fruits that cling to trousers and socks in autumn. Originally from tropical America, it is a naturalized species. Forms with conspicuous white ray florets are called Shiro-no-sendangusa, while those with few or no ray florets are Kosendangusa. The achenes have 2–4 barbed awns that attach to clothing and animal fur.
Identification Points
- ✓Achenes have 2–4 retrorsely barbed awns that cling (hitchhiker seeds)
- ✓Leaves are pinnately compound to simple, opposite
- ✓White ray florets (or absent) with yellow disc florets
- ✓Common along roadsides in autumn
Habitat
Roadsides, vacant lots, and field margins
Season
September–November (flowers)
Morphological TraitsAI-estimated, needs verification
Leaf arrangement
Opposite
Leaf type
Compound
Venation
Pinnate
Leaf margin
Serrate
Leaf shape
Ovate
Growth form
Herb
Petal count
5 petals
Petal fusion
Fused
Flowering season
Autumn
Habitat
Roadside
Ovary position
Inferior
Stamen count
1-2
Phylogenetic Positionキク科 →
Phylogenetic Position
Angiosperms > Eudicots > Core eudicots > Asterales > Asteraceae
Divergence Era
Late Cretaceous to Paleogene (approx. 80–70 million years ago)
Sources & References
AI-generated, needs verification