Article (magazine)  (2016)  
 
R. ×collaris Rydb. (pro sp.) is transferred to nothospecies status as the hybrid of R. gymnocarpa and R. woodsii Lindl.

Book  (1988)  Page(s) 142.  
 
location 147/1, R. collaris Rybd., CINNAMOMEAE, pink, single, mild fragrance, large, early-blooming, vigorous, arching-upright, 2.5-3 m, dark green medium size matte foliage, 5-7 leaflets, orange-coloured medium size matte flat-rounded fruit, upright sepals, ripe very early