Fauna
Plant

Maltese Star-thistle

Centaurea melitensis

Also known as Tocalote, Napa Thistle, Maltese Centaury

Maltese star-thistle is a wiry winter annual recognized by its resin-dotted, winged stems and compact yellow flower heads encircled by sharp, purple-tinged spines. A deep taproot allows it to tap early soil moisture before native vegetation establishes, outcompeting local flora across arid scrub and disturbed rangelands. Transported across global shipping routes and historical mission trails, it forms dense prickly stands that crowd out forage and disrupt native plant communities.

InvasiveSpinyWildflower
Maltese Star-thistle reference1 / 7
(c) Franco Folini, some rights reserved (CC BY-SA) · cc-by-sa
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Not EvaluatedConservation statusIUCN Red List categoriesLCNTVUENCREWEXNot Evaluated — not placed on the risk ladderRed List categories, explained →
Key facts
Diet & preyAutotrophic (photosynthetic)
Predators
  • Seed-head weevils
  • Peacock flies
  • Grazing sheep
ThreatsHerbicide application, biological control weevils, and mechanical mowing
HabitatsDisturbed grasslands, rangelands, roadsides, and chaparral
Life span1 year (annual)
Classification
  1. OrderAsterales
  2. FamilyAsteraceae
  3. GenusCentaurea
  4. SpeciesCentaurea melitensis
Range & activity
Range data is not available yet.
Safe observation
Interaction riskHigh
  1. Low
  2. Moderate
  3. High
  4. Very high
Why interaction risk is high
Safe to observe at a normal distance; sharp bract spines can prick bare skin.
Responsible observation
  • Footwear: Wear sturdy boots and thick pants when walking through infested areas to avoid sharp spines.
  • Seed dispersal: Check socks, pet fur, and gear for barbed seed heads before leaving to avoid spreading it.
  • Identification: Look for winged stem tissue and resin glands on leaves to distinguish it from look-alikes.
Related species
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