Agoseris attenuata Rydb. accepted as Agoseris aurantiaca (Hook.) Greene (original description)
Agoseris roseata Rydb. accepted as Agoseris aurantiaca (Hook.) Greene (original description)
Agoseris rostrata Rydb. accepted as Agoseris aurantiaca (Hook.) Greene (original description)
Antennaria sierrae-blancae Rydb. accepted as Antennaria rosulata Rydb. (original description)
Arnica coloradensis Rydb. accepted as Arnica mollis Hook. (original description)
Artemisia brittonii Rydb. accepted as Artemisia ludoviciana subsp. ludoviciana Nutt. (original description)
Artemisia dracunculoides var. wolfii Rydb. accepted as Artemisia dracunculus L. (original description)
Artemisia pudica Rydb. accepted as Artemisia ludoviciana subsp. ludoviciana Nutt. (original description)
Artemisia saxicola Rydb. (original description)
Artemisia underwoodii Rydb. (original description)
Aster fluvialis Osterh. accepted as Symphyotrichum lanceolatum (Willd.) G.L.Nesom (original description)
Carduus araneosus Osterh. (original description)
Carduus coloradensis Rydb. accepted as Cirsium scariosum var. coloradense (Rydb.) D.J.Keil (original description)
Carduus floccosus Rydb. accepted as Cirsium tracyi (Rydb.) Petr. (original description)
Carduus osterhoutii Rydb. accepted as Cirsium clavatum var. osterhoutii (Rydb.) D.J.Keil (original description)
Carduus perplexans Rydb. accepted as Cirsium perplexans (Rydb.) Petr. (original description)
Carduus spathulatus Osterh. (original description)
Carduus tracyi Rydb. accepted as Cirsium tracyi (Rydb.) Petr. (original description)
Chrysoma fasciculata Eastw. accepted as Ericameria fasciculata (Eastw.) J.F.Macbr. (original description)
Crepis angustata Rydb. accepted as Crepis acuminata Nutt. (original description)
Crepis denticulata Rydb. accepted as Crepis runcinata subsp. runcinata Torr. & A.Gray (original description)
Crepis perplexans Rydb. accepted as Crepis runcinata subsp. runcinata Torr. & A.Gray (original description)
Crepis petiolata Rydb. accepted as Crepis runcinata subsp. hispidulosa (Howell ex Rydb.) Babc. & Stebbins (original description)
Crepis tomentulosa Rydb. accepted as Crepis runcinata subsp. runcinata Torr. & A.Gray (original description)
Erigeron earlei Rydb. (original description)
Erigeron nematophyllus Rydb. (original description)
Erigeron peasei Rydb. accepted as Lachnophyllum noeanum Boiss. (original description)
Erigeron salicinus Rydb. accepted as Erigeron speciosus (Lindl.) DC. (original description)
Erigeron smithii Rydb. accepted as Erigeron formosissimus var. viscidus (Rydb.) Cronquist (original description)
Erigeron vetensis Rydb. (original description)
Erigeron vreelandii Rydb. (original description)
Gaertneria linearis Rydb. accepted as Ambrosia linearis (Rydb.) W.W.Payne (original description)
Xylorhiza brandegeei Rydb. accepted as Xanthisma coloradoense (A.Gray) D.R.Morgan & R.L.Hartm. (original description)