star-thistle
Học thuậtThân thiện
Definition
Noun A Mediterranean annual or biennial herb (genus Centaurea, especially Centaurea calcitrapa and related species) characterized by pinkish to purple flowers that are surrounded by spiny, scale-like bracts. It has become naturalized in parts of America.
Usage
The term "star-thistle" is used as a common name for specific, spiny herbaceous plants, primarily within botanical, agricultural, or ecological contexts. It refers to the plant's physical appearance, notably its star-like arrangement of spines.
Examples
- The pasture was overrun with star-thistle, making it difficult for the livestock to graze.
- Botanists are studying the spread of the invasive star-thistle in California.
- The star-thistle is easily identified by its distinctive purple flowers and sharp, radiating spines.
Advanced Usage
- As a modifier: The term can be used attributively to describe related concepts.
- Example: The county has a star-thistle control program to manage the invasive species.
Variants and Related Words
- Yellow star-thistle (): A specific and highly invasive species with yellow flowers, often simply called "star-thistle" in regions where it is prevalent.
- Barnaby's star-thistle (): Another common name for yellow star-thistle.
- Calcitrap (): A historical name for a common type of star-thistle, derived from its spiny, trap-like flower heads.
Synonyms
- Caltrop (This name is shared with other spiny plants and a metal weapon, but can refer to ).
- Knapweed (A related genus, , includes plants sometimes called star-thistles, though not all knapweeds have the same pronounced spines).
Notes
- Caution: "Star-thistle" is not a true thistle (genus or ), but is named for its similar spiny appearance. It is a member of the aster family (Asteraceae).
- The plant is often considered a noxious weed in its naturalized range due to its invasiveness and the danger its spines pose to animals and humans.
Noun
- Mediterranean annual or biennial herb having pinkish to purple flowers surrounded by spine-tipped scales; naturalized in America