• Acrostichum aureum L.
• Acrostichum citrifolium Linnaeus accepted as Anetium citrifolium (L.) Splitg.
• Acrostichum crinitum Linnaeus accepted as Elaphoglossum crinitum (L.) Christ
• Acrostichum danaeifolium Langsdorff & Fischer
• Acrostichum digitatum Linnaeus accepted as Actinostachys pennula (Sw.) Hook.
• Acrostichum excelsum Maxon accepted as Acrostichum danaeifolium Langsdorff & Fischer
• Acrostichum longifolium Jacq. accepted as Elaphoglossum longifolium J. Sm.
• Acrostichum serratifolium Mert. ex Kaulf. accepted as Bolbitis serratifolia (Mert. ex Kaulf.) Schott
• Acrostichum speciosum Wildenow
• Acrostichum thalictroides Linnaeus accepted as Ceratopteris thalictroides (L.) Brongn.
• Actinostachys digitata (L.) Wall. ex J. Sm. accepted as Schizaea digitata (L.) Sw.
• Actinostachys germanii Fée accepted as Actinostachys pennula (Sw.) Hook.
• Actinostachys pennula (Sw.) Hook.
• Aculea bifida †
• Adenophorus abbottiae W.H. Wagner
• Adenophorus abietinus (D.C. Eat.) K.A. Wilson
• Adenophorus carsonii T.A. Ranker
• Adenophorus epigaeus (Bishop) W.H. Wagner
• Adenophorus haalilioanus (Brack.) K.A. Wilson
• Adenophorus hymenophylloides (Kaulfuss) Hook. & Grev.
• Adenophorus montanus (Hbd.) W.H. Wagner
• Adenophorus oahuensis (Copeland) Bishop
• Adenophorus periens Bishop
• Adenophorus pinnatifidus Gaud.
• Adenophorus tamariscinus (Kaulfuss) Hook. & Grev.
• Adenophorus tripinnatifidus Gaud.
• Adianthum truncatum Burm. f. accepted as Acacia truncata Hoffmanns.
• Adiantopsis asplenioides Maxon
• Adiantopsis paupercula (Kunze) Fée accepted as Cheilanthes paupercula (Kunze) Mett.
• Adiantopsis pedata (Hook.) T. Moore
• Adiantopsis radiata (L.) Fée
• Adiantopsis rupicola Maxon
• Adiantum aleuticum (Rupr.) Paris
• Adiantum anceps Maxon & Morton
• Adiantum capillus-veneris Linnaeus
• Adiantum caudatum Linnaeus
• Adiantum concinnum Humb. & Bonpl. ex Willd.
• Adiantum cristatum Linnaeus accepted as Adiantum pyramidale (L.) Willd.
• Adiantum cuneatum Langsd. & Fisch. accepted as Adiantum raddianum K. Presl
• Adiantum deltoideum Sw.
• Adiantum dolosum Kunze
• Adiantum fragile Sw.
• Adiantum guianense Aubl. accepted as Lindsaea guianensis (Aubl.) Dryand.
• Adiantum hexagona auct.p.p. non L. accepted as Anopteris hexagona (L.) C. Christens.
• Adiantum hirsutum Bory
• Adiantum hispidulum Sw.
• Adiantum jordanii C. Muell.
• Adiantum latifolium Lam.
• Adiantum lucidum (Cav.) Sw.
• Adiantum macrophyllum Sw.
• Adiantum melanoleucum Willd.
• Adiantum modestum Underwood accepted as Adiantum capillus-veneris Linnaeus
• Adiantum obliquum Willd.
• Adiantum pedatum Linnaeus
• Adiantum petiolatum Desv.
• Adiantum pulverulentum Linnaeus
• Adiantum pyramidale (L.) Willd.
• Adiantum raddianum K. Presl
• Adiantum rigidulum Mett. ex Kuhn accepted as Adiantum fragile Sw.
• Adiantum tenerum Sw.
• Adiantum tetraphyllum Humb. & Bonpl. ex Willd.
• Adiantum tracyi C.C. Hall ex W.H. Wagner
• Adiantum trapeziforme Linnaeus
• Adiantum tricholepis Fée
• Adiantum truncatum Burm. f. accepted as Acacia truncata Hoffmanns.
• Adiantum villosum Linnaeus
• Adiantum viridimontanum Paris
• Adiantum vivesii Proctor
• Adiantum wilsonii Hook.
• Alamatus bifarius †
• Aleuritopteris cretacea auct. non (Liebm.) Fourn. accepted as Notholaena californica D.C. Eat.
• Alsophila amintae Conant
• Alsophila aquilina Christ accepted as Cyathea parvula (Jenman) Domin
• Alsophila boringuena Maxon accepted as Cyathea borinquena (Maxon) Domin
• Alsophila brooksii (Maxon) R. Tryon
• Alsophila bryophila R. Tryon
• Alsophila dryopteroides (Maxon) R. Tryon accepted as Alsophila amintae Conant
• Alsophila portoricensis (Spreng. ex Kuhn) Conant
• Alsophila procera (Willd.) Desv. accepted as Cyathea pungens (Willd.) Domin
• Alsophila quadripinnata (Gmel.) C. Christens. accepted as Lophosoria quadripinnata (Gmel.) C. Christens.
• Amanda floribunda †
• Amphoradenium hymenophylloides (Kaulfuss) Copeland accepted as Adenophorus hymenophylloides (Kaulfuss) Hook. & Grev.
• Amphoradenium tamariscinum (Kaulfuss) Copeland accepted as Adenophorus tamariscinus (Kaulfuss) Hook. & Grev.
• Ananthacorus angustifolius (Sw.) Underwood & Maxon accepted as Vittaria costata Kunze
• Anchistea virginica (L.) K. Presl accepted as Woodwardia virginica (L.) Sm.
• Andriania baruthina Braun †
• Anemia adiantifolia (L.) Sw.
• Anemia californica Nuttall accepted as Anemopsis californica (Nutt.) Hook. & Arn.
• Anemia cicutaria Kunze ex Spreng.
• Anemia coriacea Griseb.
• Anemia cuneata Kunze ex Spreng.
• Anemia hirsuta (L.) Sw.
• Anemia hirta (L.) Sw.
• Anemia mexicana Klotzsch
• Anemia phyllitidis (L.) Sw.
• Anemia portoricensis Maxon
• Anemia underwoodiana Maxon
• Anemia wrightii Baker
• Anetium citrifolium (L.) Splitg.
• Anisosorus hirsutus (L.) Underwood & Maxon ex Maxon accepted as Lonchitis hirsuta Linnaeus