Cirsium arizonicum, the Arizona thistle, is a North American species of thistle in the family Asteraceae, native to the southwestern United States and northwestern Mexico. It has been found in Arizona, southeastern California, New Mexico, Nevada, Colorado, Utah, Sonora, and northwestern Chihuahua.[2][3][4][5][6]

Cirsium arizonicum

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Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Asterids
Order: Asterales
Family: Asteraceae
Genus: Cirsium
Species:
C. arizonicum
Binomial name
Cirsium arizonicum
Synonyms[1]
Synonymy
  • Carduus arizonicus (A.Gray) Greene
  • Carduus nidulus (M.E.Jones) A.Heller
  • Cirsium nidulum (M.E.Jones) Petr.
  • Cnicus arizonicus A.Gray
  • Cnicus nidulus M.E.Jones
  • Cirsium effusum (Maxim.) Matsum.
  • Cnicus effusus Maxim.
  • Cirsium chellyense R.J.Moore & Frankton
  • Cirsium chuskaense R.J.Moore & Frankton
  • Cirsium navajoense R.J.Moore & Frankton
  • Carduus rothrockii (A.Gray) Greene
  • Cirsium rothrockii (A.Gray) Petr.
  • Cnicus rothrockii A.Gray

Cirsium arizonicum is a herbaceous plant that can be either biennial or perennial, reaching 30–150 cm in height. The spiny leaves are oblong-obovate with pinate lobes; the basal leaves are larger, 10–40 cm long, while leaves on the upper stem can be only 3 cm long. The inflorescence is 3–4 cm in length and 1.5–2 cm diameter, red to pink or purple, with all the florets of similar form (no division into disc and ray florets); individual plants are very variable in the number of heads produced, from one to 100. Flowering is from mid spring to mid fall. The species occurs in mountains, at elevations of 900–3,600 m.[2][3][7]

Five varieties have been identified:[2]

References

edit
  1. ^ The Plant List, Cirsium arizonicum (A.Gray) Petr.
  2. ^ a b c Flora of North America: Cirsium arizonicum
  3. ^ a b Jepson Flora: Cirsium arizonicum
  4. ^ USDA Plants Profile: Cirsium arizonicum
  5. ^ Biota of North America Program 2014 county distribution map
  6. ^ Calflora taxon report, University of Arizona, Cirsium arizonicum (A. Gray) Petrak Arizona thistle
  7. ^ SEINet Southwestern Biodiversity, Arizona Chapter, Cirsium arizonicum includes photos, description, distribution map
  8. ^ Phillips, III, Arthur (1979). Grand Canyon Wildflowers. Grand Canyon Natural History Association.