• Euphorbia Linnaeus, 1753
• Euphorbia aaron-rossii A.H. Holmgren & N.H. Holmgren
• Euphorbia abbottii Baker accepted as Euphorbia pyrifolia Lam.
• Euphorbia abbreviata Correll accepted as Euphorbia inaguaensis Oudejans
• Euphorbia abbreviata Thuill.
• Euphorbia abchazica Woronow
• Euphorbia abdelkuri Balf. f.
• Euphorbia abdita (D.G. Burch) Radcl.-Sm. accepted as Chamaesyce abdita D.G. Burch
• Euphorbia abolinii Korovin ex Pavlov accepted as Euphorbia mucronulata (Prokh.) Pavlov
• Euphorbia abortiva Forssk. (unaccepted > nomen nudum)
• Euphorbia abortiva Porta accepted as Euphorbia terracina Linnaeus
• Euphorbia abramsiana L.C. Wheeler accepted as Chamaesyce abramsiana (L.C. Wheeler) Koutnik
• Euphorbia abyssinica J.F. Gmel.
• Euphorbia acalyphoides Hochst. ex Boiss.
• Euphorbia acanthothamnos Heldr. & Sart. ex Boiss.
• Euphorbia acaulis Roxb. accepted as Euphorbia fusiformis Buch.-Ham. ex D. Don
• Euphorbia acerensis Boiss.
• Euphorbia acervata S. Carter
• Euphorbia achanocarpa Guss. ex Spreng. accepted as Euphorbia akenocarpa Guss.
• Euphorbia acrurensis N.E. Br. accepted as Euphorbia abyssinica J.F. Gmel.
• Euphorbia actinoclada S. Carter
• Euphorbia aculeata E. Mey. accepted as Euphorbia ruscifolia (Boiss.) N.E. Br.
• Euphorbia aculeata Forssk.
• Euphorbia acuminata Lam. accepted as Euphorbia falcata Linnaeus
• Euphorbia acuta Bellardi ex Colla
• Euphorbia acuta Engelm. accepted as Chamaesyce acuta Millsp.
• Euphorbia acutifolia (Boiss.) Rech. f. accepted as Euphorbia valerianifolia Lam.
• Euphorbia adenensis Deflers accepted as Euphorbia balsamifera Aiton
• Euphorbia adenochila S. Carter
• Euphorbia adenochlora C. Morren & Decne.
• Euphorbia adenophylla Steud. (unaccepted > nomen nudum)
• Euphorbia adenopoda Baill.
• Euphorbia adenoptera Bertol. accepted as Chamaesyce adenoptera (Bertol.) Small
• Euphorbia adhaerens (Small) Jabl. accepted as Chamaesyce deltoidea (Engelm. ex Chapm.) Small
• Euphorbia adiantoides Lam.
• Euphorbia adinophylla Donn. Sm. accepted as Euphorbia schlechtendalii Boiss.
• Euphorbia adjurana P.R.O. Bally & S. Carter
• Euphorbia adriana A. St.-Hil. ex Klotzsch & Garcke accepted as Euphorbia papillosa A. St.-Hil.
• Euphorbia aegyptiaca Boiss. accepted as Euphorbia forsskalii J. Gay
• Euphorbia aellenii Rech. f.
• Euphorbia aequoris N.E. Br.
• Euphorbia aeruginosa Schweick.
• Euphorbia aethiopum Croizat accepted as Euphorbia abyssinica J.F. Gmel.
• Euphorbia affinis Boiss. accepted as Chamaesyce balbisii (Boiss.) Millsp.
• Euphorbia affinis DC. accepted as Euphorbia terracina Linnaeus
• Euphorbia afzelii N.E. Br. accepted as Chamaesyce thymifolia (L.) Millsp.
• Euphorbia aggregata A. Berger
• Euphorbia agowensis Hochst. ex Boiss.
• Euphorbia agraria M. Bieb.
• Euphorbia agrorum Willd. ex Ledeb. accepted as Euphorbia agraria M. Bieb.
• Euphorbia akdaghensis Stapf accepted as Euphorbia pestalozzae Boiss.
• Euphorbia akenocarpa Guss.
• Euphorbia akenocarpa Roux & Blaise ex Boiss. accepted as Euphorbia valerianifolia Lam.
• Euphorbia alaica (Prokh.) Prokh.
• Euphorbia alainii Oudejans
• Euphorbia alata Hook.
• Euphorbia alatavica Boiss.
• Euphorbia alatocaulis V.W. Steinm. & Felger
• Euphorbia albanica N.E. Br.
• Euphorbia albertensis N.E. Br.
• Euphorbia albicaulis Rydb.
• Euphorbia albiflora Taub. accepted as Chamaesyce potentilloides (Boiss.) Croizat
• Euphorbia albipollinifera L.C. Leach
• Euphorbia albomarginata Torr. & A. Gray accepted as Chamaesyce albomarginata (Torr. & A. Gray) Small
• Euphorbia albovillosa Pax accepted as Euphorbia gueinzii Boiss.
• Euphorbia alcicornis Baker
• Euphorbia alcicornis Poiss. accepted as Euphorbia ramipressa Croizat
• Euphorbia aleppica Linnaeus
• Euphorbia alexandrina Delile accepted as Euphorbia terracina Linnaeus
• Euphorbia alfredii Rauh
• Euphorbia algeriensis Boiss. accepted as Euphorbia paniculata Desf.
• Euphorbia aliceae A. Nelson accepted as Chamaesyce exstipulata (Engelm.) Rydb.
• Euphorbia allocarpa S. Carter
• Euphorbia alluaudii Drake
• Euphorbia alpigena A. Kern. accepted as Euphorbia dulcis Linnaeus
• Euphorbia alpina C.A. Mey. ex Ledeb.
• Euphorbia alsiniflora Baill. accepted as Chamaesyce alsiniflora (Baill.) D.C. Hassall
• Euphorbia alsinifolia Boiss.
• Euphorbia alsinoides Miq.
• Euphorbia alta Norton
• Euphorbia altaica C.A. Mey. ex Ledeb.
• Euphorbia alternicolor N.E. Br. accepted as Euphorbia aggregata A. Berger
• Euphorbia altissima Boiss.
• Euphorbia altotibetica Paulsen
• Euphorbia amandi Oudejans
• Euphorbia amarifontana N.E. Br.
• Euphorbia ambacensis N.E. Br.
• Euphorbia ambarivatoensis Rauh & Bard.-Vauc.
• Euphorbia ambatofinandranae Leandri accepted as Euphorbia stenoclada Baill.
• Euphorbia ambigua Waldst. & Kit. ex Willd. accepted as Euphorbia carniolica Jacq.
• Euphorbia ambohipotsiensis Ursch & Leandri
• Euphorbia ambovombensis Rauh & Razaf.
• Euphorbia ambroseae L.C. Leach
• Euphorbia ambukensis Stepanov
• Euphorbia amicorum S. Carter
• Euphorbia ammak Schweinf.
• Euphorbia ammannioides Kunth accepted as Chamaesyce bombensis (Jacquin) Dugand, 1968
• Euphorbia ammatotricha Boiss. accepted as Chamaesyce ammatotricha (Boiss.) Millsp.
• Euphorbia amoena Klotzsch accepted as Chamaesyce adenoptera (Bertol.) Small
• Euphorbia amphimalaca Standl. accepted as Euphorbia xalapensis Kunth