Genres : B
- Babiana
- Backhousia
- Bacopa
- Baileya
- Ballota
- Bambusa
- Banksia
- Baptisia
- Barbarea
- Barleria
- Basella
- Bassia
- Bauhinia
- Beaucarnea
- Begonia
- Belamcanda
- Bellis
- Bellium
- Berberis
- Bergenia
- Berkheya
- Berteroa
- Beta
- Betonica
- Betula
- Bhesa
- Bidens
- Billbergia
- Bismarckia
- Bistorta
- Bixa
- Blechnum
- Bletilla
- Blitum
- Bloomeria
- Boehmeria
- Boesenbergia
- Bokchoonara
- Boletus
- Boltonia
- Boophone
- Borago
- Bougainvillea
- Bouteloua
- Bowiea
- Brachychiton
- Brachyglottis
- Brachyscome
- Brasiliorchis
- Brassia
- Brassica
- Brassocattleya
- Brillantaisia
- Briza
- Brodiaea
- Broussonetia
- Brugmansia
- Brunella
- Brunfelsia
- Brunnera
- Bryonia
- Buckinghamia
- Buddleja
- Bulbine
- Bulbophyllum
- Buphthalmum
- Bupleurum
- Burrageara
- Butomus
- Buxus