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Centaurea calcitrapa |
 | | Purple starthistle (Centaurea calcitrapa) is an annual to perennial thistle with a mounding growth habit and heads of purple flowers surrounded by long, stout, sharp-pointed spines. |
 | | Mature plants are one to four feet high, densely and rigidly branched, and have numerous flowerheads (Roche and Roche 1990). |
 | | The species epithet calcitrapa is derived from the word caltrop, a weapon with protruding spikes used in ancient times to obstruct the movement of cavalry. |
| ucce.ucdavis.edu /datastore/detailreport.cfm?usernumber=26&surveynumber=182 (1143 words) |
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