Centaurea: from the Latin and a reference to the Centaur Chiron who was supposed to have discovered the medicinal uses of a plant in Greece that came to be called Centaury

calcitrapa: from the Latin calcitro, "to kick," caltrop, a four-pointed weapon usually positioned on the ground to impede enemy movements

[Cal-IPC] Invasive: Centaurea calcitrapa (purple starthistle) grows as an annual, biennial or perennial (family Asteraceae) in fields, roadsides, disturbed open sites, grasslands, overgrazed rangelands, and logged areas in the northern and central coast ranges of California. Centaurea species may produce allelopathic effects and are highly competitive with other plants, often displacing desired vegetation. Cal-IPC Rating: Moderate (link added by Mary Ann Machi)

[Wikipedia] Europe native, Noxious weed: Centaurea calcitrapa is a species of flowering plant known by several common names, including red star-thistle[1] and purple star thistle. It is native to Europe but is rarely found there, it is known across the globe as an introduced species and often a noxious weed.[2][3] The species name calcitrapa comes from the word caltrop, a type of weapon covered in sharp spikes. (link added by Mary Ann Machi)