Purshia
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| DC. ex Poir. |
Purshia is a genus of plants within the rose family (Rosaceae). The five to eight species occur only in western North America .
description
Vegetative characteristics
The Purshia species are deciduous or evergreen shrubs that reach heights of 0.3 to 5 meters. The leaves are relatively small, 1 to 3 centimeters long and deep three to five lobes with revolute margins.
Generative characteristics
The hermaphroditic flowers are radially symmetrical with a diameter of 1 to 2 centimeters and five-fold with a double flower envelope . The five petals are white to pale yellow or pink in color. The stamens are yellow. The collective fruit contains dry, slender, leathery achenes 2 to 6 centimeters in length.
ecology
The roots have nodules of nitrogen-fixing bacteria of the genus Frankia .
distribution
All Purshia species are native to western North America, where they occur from southeastern British Columbia in Canada through the western United States to northern Mexico . They thrive in arid climates.
Systematics
The classification of the genus within the rose family was unclear in the last century. The genus originally belonged to the subfamily Rosoideae , but was grouped into the subfamily Dryadoideae .
The type species is Purshia tridentata .
The evergreen species used to be grouped together in the genus Cowania ; this is still accepted by some botanists.
species
- Purshia ericifolia (Torr. Ex A. Gray) Henrickson: Texas .
- Purshia glandulosa Curran: Nevada , Utah , Arizona .
- Purshia mexicana (D.Don) SLWelsh (Syn .: Cowania mexicana D.Don): Mexico, Arizona .
- Purshia pinkavae Schaack: Arizona.
- Purshia plicata (D.Don) SLWelsh (Syn .: Cowania plicata D.Don): Mexico only Nuevo León .
- Purshia stansburyana (Torr.) Henrickson (Syn .: Purshia mexicana var. Stansburiana , Cowania stansburiana ): From Idaho south to California , Arizona and New Mexico .
- Purshia subintegra (Kearney) Henrickson (possibly a hybrid between Purshia pinkavae and Purshia stansburyana ): Arizona.
- Purshia tridentata (Pursh) DC .: British Columbia south to California and New Mexico.
Purshia tridentata , Lava Beds National Monument
Purshia stansburiana , Red Rock Canyon National Conservation Area , Nevada
Purshia stansburiana , Red Rock Canyon, Nevada
Individual evidence
- ↑ Susan M. Swensen, Beth C. Mullin: The impact of molecular systematics on hypotheses for the evolution of root nodule symbioses and implications for expanding symbioses to new host plant genera . In: Plant and Soil . tape 194 , no. 1-2 , 1997, pp. 185-192 , doi : 10.1023 / A: 1004240004063 (English).
- ^ DR Morgan, DE Soltis, KR Robertson: Systematic and evolutionary implications of rbcL sequence variation in Rosaceae . In: American Journal of Botany . 81, No. 7, 1994, pp. 890-903. doi : 10.2307 / 2445770 .
- ↑ T. Eriksson, MS Hibbs, AD Yoder, CF Delwiche, MJ Donoghue: 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 . In: International Journal of Plant Sciences . 164, No. 2, 2003, pp. 197-211. doi : 10.1086 / 346163 .
- ↑ D. Potter, T. Eriksson, RC Evans, S. Oh, JEE Smedmark, DR Morgan, M. Kerr, KR Robertson, M. Arsenault: Phylogeny and classification of Rosaceae . In: Plant Systematics and Evolution . 266, No. 1-2, 2007, pp. 5-43. doi : 10.1007 / s00606-007-0539-9 .
