• Croton Linnaeus, 1753
• Croton abaitensis Baill.
• Croton abeggii Urb. & Ekman
• Croton aberrans Müll. Arg.
• Croton abnormis Mart. ex Baill. accepted as Croton timandroides (Didr.) Müll. Arg.
• Croton abruptus M.C. Johnst.
• Croton abutilifolius Croizat
• Croton abutiloides Kunth
• Croton abutilopsis G.L. Webster
• Croton acapulcensis M.J. Martinez Gordillo & J. Jiménez Ram.
• Croton acerifolius A. Cunn. ex Hook. (unaccepted)
• Croton aceroides Radcl.-Sm.
• Croton acerrimus Reinw. ex Blume accepted as Dalechampia bidentata Blume
• Croton ackermannianus (Müll. Arg.) G.L. Webster
• Croton acradenius Pax & K. Hoffm.
• Croton acronychioides F. Muell.
• Croton aculeatus Splitg. ex Lanj. accepted as Caperonia corchoroides Müll. Arg.
• Croton acuminatissimus (Pittier) G.L. Webster
• Croton acuminatus A. Rich. ex Baill. accepted as Adenochlaena leucocephala Baill.
• Croton acuminatus Lam. accepted as Mallotus japonicus (L. f.) Müll. Arg.
• Croton acuminatus R. Br. accepted as Croton macrostachyus Hochst. ex Delile
• Croton acuminatus Sessé & Moç. accepted as Croton sesseianus P.T. Li
• Croton acunae Borhidi
• Croton acutus Thunb. accepted as Croton tiglium Linnaeus
• Croton adabolavensis Leandri
• Croton adamantinus Müll. Arg.
• Croton adenocalyx Baill.
• Croton adenodontus (Müll. Arg.) Müll. Arg.
• Croton adenopetalus Müll. Arg. accepted as Croton gracilipes Baill.
• Croton adenophorus Baill.
• Croton adenophyllus Spreng.
• Croton adipatus Kunth
• Croton adpressus C. Wright & Griseb. accepted as Croton craspedotrichus Griseb.
• Croton adspersus Benth.
• Croton adumbratus Croizat accepted as Croton erythrostachys Hook. f.
• Croton aequatoris Croizat
• Croton affinis Geiseler accepted as Croton glandulosus Linnaeus
• Croton affinis Maiden & R.T. Baker accepted as Croton acronychioides F. Muell.
• Croton agoensis Baill.
• Croton agrarius Baill.
• Croton agrestis (Pax & K. Hoffm.) Radcl.-Sm. & Govaerts
• Croton agrophilus Müll. Arg.
• Croton aguilari Lundell accepted as Croton xalapensis Kunth
• Croton aigburtensis auct. accepted as Codiaeum variegatum (L.) Blume
• Croton alabamensis E.A. Sm. ex Chapm.
• Croton alagoensis Müll. Arg.
• Croton alamosanus N.E. Rose
• Croton albellus Müll. Arg.
• Croton albescens Andersson accepted as Croton scouleri Hook. f.
• Croton albicans (Blume) Rchb. f. & Zoll. accepted as Sumbaviopsis albicans (Blume) J.J. Sm.
• Croton albicans Willd. ex Schltdl. accepted as Croton heliotropiifolius Kunth
• Croton albidus Müll. Arg. accepted as Croton flavens Linnaeus
• Croton albinoides (A.M. Ferguson) Croizat accepted as Croton capitatus Michx.
• Croton alchorneicarpus Croizat
• Croton alegrensis Glaz. (unaccepted > nomen nudum)
• Croton algernonii Baill. accepted as Croton grandivelum Baill.
• Croton alienus Pax
• Croton allemii G.L. Webster
• Croton allenii Standl. accepted as Croton hircinus Vent.
• Croton alloeophyllus Urb.
• Croton alnifolius Lam.
• Croton alnoideus Baill.
• Croton alpinus A. Chev. ex Gagnep.
• Croton althaeifolius Mill.
• Croton alvaradonis M.E. Jones
• Croton amabilis Müll. Arg. accepted as Croton gratissimus Burch.
• Croton amazonicus Müll. Arg.
• Croton ambanivoulensis Baill.
• Croton ambovombensis Radcl.-Sm. & Govaerts
• Croton ameliae Lundell
• Croton amphileucus Briq.
• Croton amplifolius Airy Shaw
• Croton andinus Müll. Arg.
• Croton andreanus Linden accepted as Codiaeum variegatum (L.) Blume
• Croton andreeus Linden accepted as Codiaeum variegatum (L.) Blume
• Croton androiensis (Leandri) Leandri
• Croton angolensis Müll. Arg.
• Croton angularis Klotzsch ex Baill. accepted as Croton salutaris Casar.
• Croton angustatus Urb. accepted as Croton cascarilla (L.) L.
• Croton angustifolius (Müll. Arg.) Airy Shaw
• Croton angustifrons Müll. Arg.
• Croton angustissimus auct. accepted as Codiaeum variegatum (L.) Blume
• Croton anisatus Baill.
• Croton anisodontus Müll. Arg.
• Croton ankarensis Leandri
• Croton anomalus Pittier
• Croton anosiravensis Leandri
• Croton antae Airy Shaw
• Croton antanosiensis Leandri
• Croton antisyphiliticus Mart.
• Croton antunesii Pax accepted as Croton gratissimus Burch.
• Croton apetalus Blume accepted as Alchornea rugosa (Lour.) Müll. Arg.
• Croton apicifolius Croizat
• Croton apostolon Radcl.-Sm. & Govaerts
• Croton appendiculatus Elmer accepted as Mallotus paniculatus (Lam.) Müll. Arg.
• Croton appertii J. Léonard
• Croton araripensis Croizat
• Croton arboreus Millsp.
• Croton ardisioides Hook. f. accepted as Croton heterocarpus Müll. Arg.
• Croton arechavaletae Herter ex Arechav.