| Bouteloua trifida Thurb. ex S. Watson, 1883 |
| Bouteloua trifida var. burkii (Scribn. ex S. Watson) Vasey ex L.H. Dewey, 1894 |
| Bouteloua trinii (E. Fourn.) Griffiths, 1912 |
| Bouteloua uniflora Vasey, 1891 |
| Bouteloua uniflora var. coahuilensis Gould & Kapadia, 1964 |
| Bouteloua uniflora var. uniflora Vasey, 1891 |
| Bouteloua varia (Swallen) Columbus, 1999 |
| Bouteloua vestita (S. Watson) Scribn. ex L.H. Dewey, 1894 |
| Bouteloua warnockii Gould & Kapadia, 1962 |
| Bouteloua williamsii Swallen, 1955 |
| Boutelouinae Stapf, 1917 |
| Brachatera Desv., 1810 |
| Brachiaria (Trin.) Griseb., 1853 |
| Brachiaria Trin., 1826 |
| Brachiaria arizonica (Scribn. & Merr.) S.T. Blake, 1969 |
| Brachiaria arizonica var. laeviglumis (Scribn. & Merr.) Beetle, 1982 |
| Brachiaria arizonica var. major (Vasey) Beetle, 1982 |
| Brachiaria arizonica var. tenuis (Scribn. & Merr.) Beetle, 1982 |
| Brachiaria brizantha (Hochst. ex A. Rich.) Stapf, 1919 |
| Brachiaria ciliatissima (Buckley) Chase, 1920 |