Oaxacania malvaefolia Robinson & Greenman                                               Isotype

Ocotea Athroanthes C. K. Allen                                                                     Isotype

Ocotea bakeri Blake                                                                                        Isotype

Ocotea eucuneata Lundell                                                                               Isotype

Ocotea portoricensis Mez.                                                                              Isosyntype

Ocotea racemifolia Lundell                                                                             Isotype

Ocotea rugosa van der Werff                                                                           Unknown

Ocotea sericiflora C. K. Allen                                                                         Isotype

Ocotea truncata Lundell                                                                                  Isotype

Ocotea venosa Lundell                                                                                    Isotype

Oenanthe pringlei Coulter & Rose                                                                  Isotype

Oenothera niveifolia Gandoger                                                                       Isotype

Oenothera sinuata var. drummondii subvar helleriana H. Levl.                      Isolectotype

Oenothera tenuissima Jones                                                                            Isotype

Oenothera triloba var. ecristata M. E. Jones                                                  Isolectotype

Oldenlandia pringlei Robinson                                                                        Isotype

Oldenlandia xestoperma Robins. & Greenm.                                                  Isolectotype

Oligonema heterophylla Watson                                                                     Isotype

Olivaea leptocarpa De Jong & Beaman                                                           Holotype

Orcuttia californica Vasey                                                                              Isotype

Oreomyrrhis orizabae I. M. Johnst.                                                                 Isotype

Oreomyrrhis tolucana I. M. Johnst.                                                                 Isotype

Ornithocarpa fimbriata Rose                                                                          Isotype

Orthocarpus bicolor Heller                                                                              Isotype

Orthocarpus tenuis Heller                                                                               Isotype

Orthocarpus venustus Heller                                                                           Isotype

Oteiza scandens Panero & Villasenor                                                               Isotype

Othake robustum Rydberg                                                                              Isotype

Otopappus alternifolius Robinson                                                                   Isotype

Otopappus robustus Hemsley                                                                          Isotype

Oxalis breviramulosa Rusby                                                                           Isotype

Oxalis filipes Small                                                                                          Isotype

Oxalis grandis Small                                                                                        Isosyntype

Oxalis halpamensis Knuth                                                                               Isotype

Oxalis latifolia H.B.K.                                                                                    Unknown

Oxalis pilgeri Knuth                                                                                        Isotype

Oxylobus oaxacanus S. F. Blake                                                                     Holotype

Oxytropis cusickii Greenman                                                                           Isosyntype