• Baudinia J.B.L.T. Leschenault de la Tour ex A.P. de Candolle, 1828 accepted as Calothamnus Labillardière, 1806 [Family: Myrtaceae]
• Baudinia J.B.L.T. Leschenault de la Tour ex A.P. de Candolle, 1839 accepted as Scaevola Linnaeus, 1771 [Family: Goodeniaceae]
• Bauhinia Linnaeus, 1753
• Bodenia Ivanova, 1959 †
• Bodinia George, 2004 [Family: Argestidae]
• Bodinia M. Ota & M. Langeron, 1923 accepted as Trichophyton Malmsten, 1848 [Family: Arthrodermataceae]
• Bohainia Gong & Wang, 1987 † (uncertain)
• Bohlinia Lemmermann, 1899 [Family: Oocystaceae]
• Bohlinia Matthew, 1929 † [Family: Giraffidae]
• Boidinia J.A. Stalpers & K. Hjortstam in K. Hjortstam & J.A. Stalpers, 1982
• Bolinia (Nitschke) P.A. Saccardo, 1882 accepted as Camarops P.A. Karsten, 1873 [Family: Boliniaceae]
• Bolinia Yabe, 1991 [Family: Cottidae]
• Boninia Bock, 1923 [Family: Boniniidae]
• Boninia Planchon, 1872 [Family: Rutaceae]
• Boreania Karatajute-Talimaa, 1985 † (uncertain)
• Boresinia Chou in Chou, Chao & Chiang, 1983 (uncertain)
• Borkinia † (uncertain)
• Bosedinia He, 1984 †
• Boueina F. Toula, 1884 †
• Bouetia A. Chevalier, 1912 accepted as Hemizygia (Bentham) Briquet in Engler & Prantl, 1897
• Bougisia Laval, 1966
• Bourginia Cachan, 1952 (uncertain)
• Boursinia Brandt, 1938
• Boutonia A.P. de Candolle, 1838 [Family: Acanthaceae]
• Boutonia W. Bojer, 1846 accepted as Hancea B.C. Seemann, 1857 [Family: Euphorbiaceae]
• Bovienia Fuhrmann in Kükenthal & Krumbach, 1931
• Bowenia Haast, 1873 accepted as Rhombosolea Günther, 1862 [Family: Pleuronectidae]
• Bowenia J.D. Hooker, 1863 [Family: Zamiaceae]
• Boykinia Nuttall, 1834
• Brusinia Števčić, 1991
• Buenia Iljin, 1930
• Butinia Boissier, 1838 accepted as Conopodium W.D.J. Koch, 1824
• Buzinia Perrichot, Nel & Neraudeau, 2007 †