Agoseris glauca subsp. aspera (Rydb.) Piper accepted as Agoseris glauca (Pursh) Raf. (original description)
Agoseris glauca subsp. scorzonerifolia (Schrad.) Piper accepted as Agoseris glauca (Pursh) Raf. (original description)
Agoseris heterophylla subsp. californica Piper accepted as Agoseris heterophylla (Nutt.) Greene (original description)
Agoseris heterophylla subsp. glabrata Piper (original description)
Ambrosia artemisiifolia subsp. diversifolia Piper accepted as Ambrosia polystachya DC. (original description)
Antennaria concolor Piper accepted as Antennaria howellii subsp. petaloidea (Fernald) R.J.Bayer (original description)
Artemisia atomifera Piper accepted as Artemisia ludoviciana subsp. incompta (Nutt.) D.D.Keck (original description)
Aster campestris subsp. suksdorfii Piper accepted as Symphyotrichum campestre (Nutt.) G.L.Nesom (original description)
Aster foliaceus subsp. apricus (A.Gray) Piper accepted as Symphyotrichum foliaceum var. apricum (A.Gray) G.L.Nesom (original description)
Aster foliaceus subsp. frondeus (A.Gray) Piper accepted as Symphyotrichum foliaceum var. parryi (D.C.Eaton) G.L.Nesom (original description)
Aster laevis subsp. geyeri (A.Gray) Piper accepted as Symphyotrichum laeve (L.) Á.Löve & D.Löve (original description)
Aster occidentalis subsp. intermedius (A.Gray) Piper accepted as Symphyotrichum spathulatum var. intermedium (A.Gray) G.L.Nesom (original description)
Carduus palousensis Piper accepted as Cirsium brevifolium Nutt. (original description)
Chrysothamnus nauseosus subsp. graveolens (Nutt.) Piper accepted as Ericameria nauseosa var. graveolens (Nutt.) Reveal & Schuyler (original description)
Chrysothamnus viscidiflorus subsp. lanceolatus (Nutt.) Piper accepted as Chrysothamnus viscidiflorus subsp. lanceolatus (Nutt.) H.M.Hall & Clem. (original description)
Erigeron acris subsp. debilis (A.Gray) Piper accepted as Erigeron nivalis Nutt. (original description)
Erigeron compositus subsp. discoideus (A.Gray) Piper accepted as Erigeron compositus Pursh (original description)
Erigeron compositus subsp. trifidus (Hook.) Piper accepted as Erigeron trifidus Hook. (original description)
Erigeron eradiatus (A.Gray) Piper (original description)
Erigeron hispidissimus (Hook.) Piper accepted as Erigeron pumilus subsp. intermedius Cronquist (original description)
Erigeron linearis (Hook.) Piper (original description)
Erigeron salsuginosus subsp. angustifolius (A.Gray) Piper accepted as Erigeron glacialis (Nutt.) A.Nelson (original description)
Eucephalus glaucophyllus Piper accepted as Eucephalus glaucescens (A.Gray) Greene (original description)
Grindelia nana subsp. columbiana Piper accepted as Grindelia hirsutula Hook. & Arn. (original description)
Hoorebekia carthamoides (Hook.) Piper accepted as Pyrrocoma carthamoides var. carthamoides Hook. (original description)
Hoorebekia carthamoides subsp. cusickii (A.Gray) Piper accepted as Pyrrocoma carthamoides var. cusickii (A.Gray) Kartesz & Gandhi (original description)
Hoorebekia greenei subsp. mollis (A.Gray) Piper accepted as Ericameria greenei (A.Gray) G.L.Nesom (original description)
Hoorebekia hallii (A.Gray) Piper accepted as Columbiadoria hallii (A.Gray) G.L.Nesom (original description)
Hoorebekia hirta (A.Gray) Piper accepted as Pyrrocoma hirta (A.Gray) Greene (original description)
Hoorebekia lanuginosa (A.Gray) Piper accepted as Stenotus lanuginosus (A.Gray) Greene (original description)
Hoorebekia lyallii (A.Gray) Piper accepted as Tonestus lyallii (A.Gray) A.Nelson (original description)
Hoorebekia racemosa (Nutt.) Piper accepted as Pyrrocoma racemosa (Nutt.) Torr. & A.Gray (original description)
Hoorebekia stenophylla (A.Gray) Piper accepted as Nestotus stenophyllus (A.Gray) R.P.Roberts, Urbatsch & Neubig (original description)
Lactuca scariola subsp. integrata (Gren. & Godr.) Piper accepted as Lactuca serriola L. (original description)
Madia exigua subsp. macrocephala (Suksd.) Piper accepted as Madia exigua (Sm.) A.Gray (original description)
Madia madioides Piper accepted as Anisocarpus madioides Nutt. (original description)
Madia sativa subsp. capitata (Nutt.) Piper accepted as Madia sativa Molina (original description)
Senecio ductoris Piper accepted as Senecio fremontii Torr. & A.Gray (original description)
Senecio exaltatus subsp. ochraceus Piper accepted as Senecio integerrimus var. ochroleucus (A.Gray) Cronquist (original description)
Senecio fastigiatus subsp. macounii (Greene) Greenm. accepted as Packera macounii (Greene) W.A.Weber & Á.Löve (original description)
Senecio fraternus Piper (original description)
Senecio pauciflorus subsp. fallax Greenm. accepted as Packera indecora (Greene) Á.Löve & D.Löve (original description)
Senecio serra subsp. lanceolatus Piper (original description)
Senecio vaseyi Greenm. ex Piper accepted as Senecio integerrimus var. exaltatus (Nutt.) Cronquist (original description)
Solidago serotina subsp. salebrosa (Piper) Piper (original description)
Xanthium oligacanthum Piper accepted as Xanthium strumarium L. (original description)