Achillea lanulosa var. alpicola Rydb. accepted as Achillea millefolium L. (original description)
Agoseris altissima Rydb. accepted as Agoseris glauca (Pursh) Raf. (original description)
Agoseris carnea Rydb. accepted as Agoseris aurantiaca (Hook.) Greene (original description)
Agoseris greenei (A.Gray) Rydb. accepted as Agoseris aurantiaca (Hook.) Greene (original description)
Agoseris leontodon Rydb. accepted as Agoseris parviflora (Nutt.) D.Dietr. (original description)
Agoseris leontodon var. pygmaea Rydb. accepted as Agoseris glauca (Pursh) Raf. (original description)
Agoseris pumila (Nutt.) Rydb. accepted as Agoseris glauca (Pursh) Raf. (original description)
Agoseris villosa Rydb. accepted as Agoseris glauca (Pursh) Raf. (original description)
Anaphalis subalpina (A.Gray) Rydb. accepted as Anaphalis margaritacea (L.) Benth. & Hook.f. (original description)
Antennaria anaphaloides Rydb. (original description)
Antennaria bracteosa Rydb. (original description)
Antennaria flavescens Rydb. accepted as Antennaria umbrinella Rydb. (original description)
Antennaria foliacea var. humilis Rydb. accepted as Antennaria rosea subsp. confinis (Greene) R.J.Bayer (original description)
Antennaria oblanceolata Rydb. accepted as Antennaria luzuloides subsp. luzuloides Torr. & A.Gray (original description)
Arnica amplexifolia Rydb. accepted as Pentacalia amplexicaulis (Kunth) Cuatrec. (original description)
Arnica monocephala Rydb. accepted as Arnica fulgens Pursh (original description)
Arnica pumila Rydb. accepted as Arnica cordifolia Hook. (original description)
Artemisia elatior (Torr. & A.Gray) Rydb. accepted as Artemisia tilesii Ledeb. (original description)
Artemisia latiloba (Nutt.) Rydb. accepted as Artemisia ludoviciana subsp. candicans (Rydb.) D.D.Keck (original description)
Artemisia tenuis Rydb. (original description)
Artemisia tenuis var. integerrima Rydb. (original description)
Artemisia tripartita (Nutt.) Rydb. (original description)
Aster amplexifolius Rydb. accepted as Eurybia integrifolia (Nutt.) G.L.Nesom (original description)
Aster apricus (A.Gray) Rydb. accepted as Symphyotrichum foliaceum var. apricum (A.Gray) G.L.Nesom (original description)
Aster brevibracteatus Rydb. (original description)
Aster ciliomarginatus Rydb. (original description)
Aster scribneri Rydb. (original description)
Aster subracemosus Rydb. (original description)
Aster subspathulatus Rydb. accepted as Symphyotrichum sericeum (Vent.) G.L.Nesom (original description)
Carduus canovirens Rydb. accepted as Cirsium cymosum var. canovirens (Rydb.) D.J.Keil (original description)
Carduus flodmanii Rydb. accepted as Cirsium flodmanii (Rydb.) Arthur (original description)
Carduus kelseyi Rydb. accepted as Cirsium scariosum var. coloradense (Rydb.) D.J.Keil (original description)
Carduus scopulorum Rydb. (original description)
Carduus tweedyi Rydb. accepted as Cirsium eatonii var. murdockii S.L.Welsh (original description)
Chrysopsis depressa Rydb. accepted as Heterotheca villosa var. depressa (Rydb.) Semple (original description)
Chrysothamnus nauseosus var. albicaulis (Nutt.) Rydb. accepted as Ericameria nauseosa var. speciosa (Nutt.) G.L.Nesom & G.I.Baird (original description)
Crepis gracilis (D.C.Eaton) Rydb. accepted as Crepis atribarba A.Heller (original description)
Crepis pumila Rydb. accepted as Crepis occidentalis subsp. pumila (Rydb.) Babc. & Stebbins (original description)
Crepis runcinata var. hispidulosa Howell ex Rydb. accepted as Crepis runcinata subsp. hispidulosa (Howell ex Rydb.) Babc. & Stebbins (original description)
Dugaldia hoopesii (A.Gray) Rydb. accepted as Hymenoxys hoopesii (A.Gray) Bierner (original description)
Erigeron conspicuus Rydb. accepted as Erigeron speciosus (Lindl.) DC. (original description)
Erigeron debilis (A.Gray) Rydb. accepted as Erigeron nivalis Nutt. (original description)
Erigeron gracilis Rydb. (original description)
Erigeron multifidus Rydb. accepted as Erigeron compositus Pursh (original description)
Erigeron multifidus var. discoideus (A.Gray) Rydb. accepted as Erigeron compositus Pursh (original description)
Eriophyllum leucophyllum (DC.) Rydb. accepted as Eriophyllum lanatum var. leucophyllum (DC.) W.R.Carter & C.F.Newc. (original description)
Eriophyllum multiflorum (Nutt.) Rydb. accepted as Eriophyllum lanatum var. integrifolium (Hook.) Smiley (original description)
Gnaphalium lagopodioides Rydb. accepted as Pseudognaphalium stramineum (Kunth) Anderb. (original description)
Gnaphalium sulphurescens Rydb. accepted as Pseudognaphalium stramineum (Kunth) Anderb. (original description)
Helianthus subrhomboideus Rydb. accepted as Helianthus pauciflorus subsp. subrhomboideus (Rydb.) O.Spring & E.E.Schill. (original description)
Hieracium griseum Rydb. (original description)
Hulsea carnosa Rydb. accepted as Hulsea algida A.Gray (original description)
Lactuca multifida Rydb. (original description)
Machaeranthera linearis Rydb. accepted as Dieteria canescens var. canescens (Pursh) Nutt. (original description)
Macronema grindelifolium Rydb. (original description)
Macronema lineare Rydb. accepted as Ericameria linearis (Rydb.) R.P.Roberts & Urbatsch (original description)
Nabalus sagittata Rydb. (original description)
Oreastrum haydenii (Porter) Rydb. (original description)
Ptiloria ramosa Rydb. accepted as Stephanomeria runcinata Nutt. (original description)
Pyrrocoma lyallii (A.Gray) Rydb. accepted as Tonestus lyallii (A.Gray) A.Nelson (original description)
Senecio alpicola Rydb. accepted as Packera werneriifolia (A.Gray) W.A.Weber & Á.Löve (original description)
Senecio altus Rydb. accepted as Senecio sphaerocephalus Greene (original description)
Senecio arachnoideus Rydb. (original description)
Senecio atriapiculatus Rydb. (original description)
Senecio glaucescens Rydb. accepted as Senecio lugens Richardson (original description)
Senecio glauciifolius Rydb. accepted as Senecio eremophilus var. eremophilus Richardson (original description)
Senecio hydrophiloides Rydb. (original description)
Senecio latus Rydb. accepted as Senecio sphaerocephalus Greene (original description)
Senecio nephrophyllus Rydb. accepted as Packera debilis (Nutt.) W.A.Weber & Á.Löve (original description)
Senecio occidentalis (A.Gray) Rydb. accepted as Senecio fremontii var. occidentalis A.Gray (original description)
Senecio occidentalis var. rotundatus Rydb. accepted as Senecio fremontii var. fremontii Torr. & A.Gray (original description)
Senecio pereziifolius Rydb. accepted as Senecio hydrophiloides Rydb. (original description)
Senecio scribneri Rydb. accepted as Senecio integerrimus var. scribneri (Rydb.) T.M.Barkley (original description)
Senecio semiamplexicaulis Rydb. accepted as Senecio crassulus A.Gray (original description)
Senecio solidago Rydb. accepted as Senecio serra var. serra Hook. (original description)
Senecio solitarius Rydb. (original description)
Senecio variifolius Rydb. (original description)
Solidago oreophila Rydb. accepted as Solidago simplex var. simplex (original description)
Taraxacum eriophorum Rydb. (original description)
Taraxacum scopulorum (A.Gray) Rydb. (original description)
Thelesperma marginatum Rydb. accepted as Thelesperma subnudum A.Gray (original description)
Townsendia alpina (A.Gray) Rydb. (original description)