Dryadoideae

White Mountain Avens ( Dryas octopetala )

The Dryadoideae are a subfamily of the rose family ( Rosaceae ) and includes four genera.

The representatives of the Dryadoideae are dwarf shrubs, shrubs or trees. The leaves are simple, assembled Chamaebatia. Stipules are present. The flower cup ( hypanthium ) is not fused with the gynoecium. It is a carpel or ( at Cowania and Dryas ) four to many present. The fruits are achenes.

Cyanogenic glycosides present, sorbitol is present in traces. The basic chromosome number is x = 9, all representatives are diploid (2n = 18).

The types operate symbiotic nitrogen fixation.

System

The Dryadoideae are one of the three subfamilies of the rose family, the position of the subfamilies to each other is not yet clear. The subfamily has long been out as tribus Dryadeae, by Potter et al. 2007 but raised to the rank of a subfamily. It comprises four genera:

• Silver Wurzen ( Dryas )
• Chamaebatia
• Purshia (including Cowania )
• Cercocarpus

Documents

• D. Potter, T. Eriksson, RC Evans, S. Oh, JEE Smedmark, DR Morgan, M. Kerr, KR Robertson, M. Arsenault, TA Dickinson, CS Campbell: Phylogeny and classification of Rosaceae. Plant Systematics and Evolution, Volume 266, 2007, pp. 5-43. doi: 10.1007/s00606-007-0539-9