Purshia

Purshia (bitterbrush or cliff-rose) is a small genus of 5-8 species of flowering plants in the family Rosaceae, native to western North America, where they grow in dry climates from southeast British Columbia in Canada south throughout the western United States to northern Mexico. The classification of Purshia within the Rosaceae has been unclear.[1][2] The genus was originally placed in the subfamily Rosoideae, but is now placed in subfamily Dryadoideae.[3]

Purshia
Purshia stansburyana
Scientific classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Eudicots
Clade: Rosids
Order: Rosales
Family: Rosaceae
Subfamily: Dryadoideae
Genus: Purshia
DC. ex Poir.
Type species
Purshia tridentata
Species

See text

The range of Purshia.
Synonyms
  • Cowania D.Don ex Tilloch & Taylor
  • Greggia Engelm.
  • Kunzia Spreng.

They are deciduous or evergreen shrubs, typically reaching 0.3–5 m tall. The leaves are small, 1–3 cm long, deeply three- to five-lobed, with revolute margins. The flowers are 1–2 cm diameter, with five white to pale yellow or pink petals and yellow stamens. The fruit is a cluster of dry, slender, leathery achenes 2–6 cm long. The roots have root nodules that host the nitrogen-fixing bacterium Frankia.[4]

The evergreen species were treated separately in the genus Cowania in the past; this genus is still accepted by some botanists.

Taxonomy

Species

Purshia comprises the following species:[5][6]

  • Purshia ericifolia (Torr. ex A.Gray) Henr. – Heath cliffrose (Texas)
  • Purshia glandulosa Curran – Desert bitterbrush (Nevada, Utah, Arizona)
  • Purshia mexicana (D.Don) Henr. – Mexican cliffrose (Mexico, Arizona)
  • Purshia pinkavae Schaack – Pinkava's cliffrose (Arizona)
  • Purshia plicata (D.Don) Henrard (syn. Cowania plicata) – Antelope bush (Nuevo León, Mexico).
  • Purshia stansburyana (Torr.) Henr. – Stansbury cliffrose (Idaho south to California, Arizona and New Mexico)
  • Purshia tridentata (Pursh) DC. – Antelope bitterbrush (British Columbia south to California and New Mexico)

Hybrids

The following hybrid has been described:[5]

  • Purshia × subintegra (Kearney) Henr. (P. pinkavae × P. stansburyana) – (Arizona)

Species names with uncertain taxonomic status

The status of the following species and hybrids is unresolved:[5]

  • Purshia ciliata Dennst.
  • Purshia mollis  Lehm.
  • Purshia plicata (D.Don) Henr.
  • Purshia subintegra (Kearney) Henrickson

References
  1. Morgan, D.R.; Soltis, D.E.; Robertson, K.R. (1994). "Systematic and evolutionary implications of rbcL sequence variation in Rosaceae". American Journal of Botany. 81 (7): 890–903. doi:10.1002/j.1537-2197.1994.tb15570.x. JSTOR 2445770.
  2. Eriksson, T.; Hibbs, M.S.; Yoder, A.D.; Delwiche, C.F.; Donoghue, M.J. (2003). "The phylogeny of Rosoideae (Rosaceae) based on sequences of the internal transcribed spacers (ITS) of nuclear ribosomal DNA and the trnL/F region of chloroplast DNA". International Journal of Plant Sciences. 164 (2): 197–211. doi:10.1086/346163.
  3. Potter, D.; Eriksson, T.; Evans, R.C.; Oh, S.; Smedmark, J.E.E.; Morgan, D.R.; Kerr, M.; Robertson, K.R.; Arsenault, M.; Dickinson, T.A.; Campbell, C.S. (2007). "Phylogeny and classification of Rosaceae". Plant Systematics and Evolution. 266 (1–2): 5–43. doi:10.1007/s00606-007-0539-9.
  4. Swensen, S.M.; Mullin, B.C. (1997). "The impact of molecular systematics on hypotheses for the evolution of root nodule symbioses and implications for expanding symbioses to new host plant genera". Plant and Soil. 194 (1–2): 185–192. doi:10.1023/A:1004240004063.
  5. "The Plant List entry for Purshia". The Plant List, v.1.1. Royal Botanic Gardens, Kew and the Missouri Botanical Garden. September 2013. Retrieved 15 December 2020.
  6. Govaerts R. "Purshia DC. ex Poir.". Plants of the World Online. Board of Trustees of the Royal Botanic Gardens, Kew. Retrieved 15 December 2020.

Media related to
Purshia at Wikimedia Commons



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