• Trifolium Linnaeus, 1753 [Family: Fabaceae]
• Trifolium Travassos, 1922 (uncertain) [Family: Trematoda (awaiting allocation)]
• Trifolium abyssinicum D. Heller
• Trifolium acaule A. Rich.
• Trifolium aciculare Torr. & A. Gray accepted as Trifolium willdenovii Spreng.
• Trifolium acutiflorum Murb.
• Trifolium adscendens Hornem. accepted as Trifolium reflexum Linnaeus
• Trifolium affine C. Presl
• Trifolium africanum Ser.
• Trifolium agrarium L., p.p. accepted as Trifolium campestre Schreb.
• Trifolium agrarium Linnaeus accepted as Trifolium aureum Pollich
• Trifolium agrestinum Boreau accepted as Trifolium arvense Linnaeus
• Trifolium aintabense Boiss. & Hausskn.
• Trifolium aitonii Rydb. accepted as Trifolium latifolium (Hook.) Greene
• Trifolium albens Loudon accepted as Trifolium lupinaster Linnaeus
• Trifolium albopurpureum Torr. & A. Gray
• Trifolium alexandrinum Linnaeus
• Trifolium alexandrinum sensu auct. accepted as Trifolium constantinopolitanum Ser.
• Trifolium alexandrium Linnaeus accepted as Trifolium alexandrinum Linnaeus
• Trifolium alpestre Linnaeus
• Trifolium alpinum Linnaeus
• Trifolium altissimum Hook. accepted as Trifolium douglasii House
• Trifolium altissimum Torr. & A. Gray accepted as Trifolium beckwithii S. Watson
• Trifolium amabile Kunth
• Trifolium ambiguum M. Bieb.
• Trifolium amoenum Greene accepted as Trifolium dichotomum Hook. & Arn.
• Trifolium amphianthum Torr. & A. Gray accepted as Trifolium polymorphum Poir.
• Trifolium amphicarpum Phil. accepted as Trifolium polymorphum Poir.
• Trifolium amplectens Torr. & A. Gray accepted as Trifolium depauperatum Desv.
• Trifolium anatolicum Boiss. accepted as Trifolium hybridum Linnaeus
• Trifolium andersonii A. Gray
• Trifolium andinum Torr. & A. Gray
• Trifolium andrewsii (A. Gray) A. Heller accepted as Trifolium barbigerum Torr.
• Trifolium anemophilum Greene accepted as Trifolium dasyphyllum Torr. & A. Gray
• Trifolium angulatum Waldst. & Kit.
• Trifolium angustifolium Linnaeus
• Trifolium ankaratrense Bosser
• Trifolium ankaratrensis Bosser accepted as Trifolium ankaratrense Bosser
• Trifolium anodon Greene accepted as Trifolium depauperatum Desv.
• Trifolium antucoensis D. Heller
• Trifolium apertum Bobrov
• Trifolium appendiculatum Lojac. accepted as Trifolium variegatum Torr. & A. Gray
• Trifolium arcuatum Piper accepted as Trifolium eriocephalum Torr. & A. Gray
• Trifolium arenivagum Boreau accepted as Trifolium arvense Linnaeus
• Trifolium argentinense Speg. accepted as Trifolium polymorphum Poir.
• Trifolium argutum Sol.
• Trifolium arizonicum Greene accepted as Trifolium mucronatum Spreng.
• Trifolium arvense Linnaeus
• Trifolium arvense Walter accepted as Trifolium carolinianum Michx.
• Trifolium arvernense Lamotte accepted as Trifolium pallescens Schreb.
• Trifolium atrorubens (Greene) House accepted as Trifolium longipes Torr. & A. Gray
• Trifolium attenuatum Greene
• Trifolium aurantiacum Boiss. & Spruner accepted as Trifolium brutium Ten.
• Trifolium aureum Pollich
• Trifolium austinae McDermott accepted as Trifolium eriocephalum Torr. & A. Gray
• Trifolium axillare Phil. accepted as Trifolium glomeratum Linnaeus
• Trifolium baccarinii Chiov.
• Trifolium badium Schreb.
• Trifolium baeticum Boiss. accepted as Trifolium pratense Linnaeus
• Trifolium baicalense Belyaeva & Sipliv. accepted as Trifolium lupinaster Linnaeus
• Trifolium balansae Boiss. accepted as Trifolium michelianum Savi
• Trifolium balbisianum Ser. accepted as Trifolium montanum Linnaeus
• Trifolium barbeyi Gibelli & Belli
• Trifolium barbigerum Torr.
• Trifolium barnebyi (Isely) Dorn & Lichvar
• Trifolium basileianum Chiov. accepted as Trifolium burchellianum Ser.
• Trifolium beckwithii S. Watson
• Trifolium bejariense Moric.
• Trifolium berytheum Boiss. & Blanche
• Trifolium biasolettii Steud. & Hochst. accepted as Trifolium repens Linnaeus
• Trifolium bicephalum Elmer accepted as Trifolium macraei Hook. & Arn.
• Trifolium biebersteinii Boiss.
• Trifolium bifidum A. Gray
• Trifolium biflorum Linnaeus accepted as Stylosanthes biflora (L.) Britton et al.
• Trifolium bilineatum Fresen.
• Trifolium bithynicum Boiss.
• Trifolium bivonae Guss.
• Trifolium bobrovii Khalilov
• Trifolium bocconei Savi
• Trifolium boissieri Guss.
• Trifolium bolanderi A. Gray
• Trifolium bolivianum P.B. Kenn. accepted as Trifolium amabile Kunth
• Trifolium bonannii C. Presl accepted as Trifolium fragiferum Linnaeus
• Trifolium bordzilowskyi Grossh.
• Trifolium borysthenicum Gruner accepted as Trifolium pratense Linnaeus
• Trifolium brachyodon (Celak.) A. Kern. accepted as Trifolium arvense Linnaeus
• Trifolium brachyodon Greene accepted as Trifolium depauperatum Desv.
• Trifolium brachypus (S. Watson) Blank. accepted as Trifolium rusbyi Greene
• Trifolium bracteatum Schousb. accepted as Trifolium pratense Linnaeus
• Trifolium bracteolatum Rydb. accepted as Trifolium attenuatum Greene
• Trifolium brandegei S. Watson
• Trifolium brevipes Phil. accepted as Trifolium polymorphum Poir.
• Trifolium breweri S. Watson
• Trifolium brittingeri Opiz accepted as Trifolium arvense Linnaeus
• Trifolium brutium Ten.
• Trifolium buckwestiorum Isely
• Trifolium bullatum Boiss. & Hausskn.
• Trifolium burchellianum Ser.
• Trifolium caerulea Linnaeus accepted as Trigonella caerulea (L.) Ser.
• Trifolium caeruleum Linnaeus accepted as Trigonella caerulea (L.) Ser.