Géneros de organismos asociados: Oberna [6 taxones], Obryzum [1 taxon], Ocalea [1 taxon], Ochlandra [15 taxones], Ochna [53 taxones], Ochrocarpos [7 taxones], Ochroconis [6 taxones], Ochrolechia [17 taxones], Ochroma [5 taxones], Ochrosia [1 taxon], Ochthocosmus [15 taxones], Ocimum [124 taxones], Ocotea [430 taxones], Octoknema [1 taxon], Octomeria [1 taxon], Odina [13 taxones], Odocoileus [96 taxones], Odontadenia [3 taxones], Odontesthes [2 taxones], Odontites [83 taxones], Odontoglossum [12 taxones], Odontonema [5 taxones], Odontotermes [9 taxones], Odontotrema [1 taxon], Oedaleus [1 taxon], Oedemium [3 taxones], Oedocephalum [2 taxones], Oedogonium [7 taxones], Oenanthe [23 taxones], Oenocarpus [26 taxones], Oenothera [128 taxones], Oidiodendron [11 taxones], Oidium [106 taxones], Ojibwaya [2 taxones], Olax [15 taxones], Oldenlandia [55 taxones], Oldfieldia [1 taxon], Olea [720 taxones], Oleander [1 taxon], Oleandra [1 taxon], Olearia [9 taxones], Oliganthes [22 taxones], Olinia [37 taxones], Olivea [3 taxones], Olmedia [3 taxones], Olpidiopsis [36 taxones], Olpidium [29 taxones], Olyra [82 taxones], Omalotheca [2 taxones], Ombrophila [1 taxon], Omega [18 taxones], Ommatospora [2 taxones], Ommatosporella [11 taxones], Omphalea [14 taxones], Omphalina [1 taxon], Omphalodes [1 taxon], Omphalospora [1 taxon], Onagra [1 taxon], Oncidium [44 taxones], Oncinotis [19 taxones], Oncoba [17 taxones], Oncopodium [7 taxones], Oncorhynchus [2 taxones], Oncosperma [21 taxones], Oncosporomyces [19 taxones], Onobrychis [163 taxones], Onoclea [2 taxones], Ononis [76 taxones], Onopordon [39 taxones], Onopordum [48 taxones], Onosma [19 taxones], Onychium [1 taxon], Oospora [3 taxones], Opegrapha [82 taxones], Operculina [11 taxones], Ophiobolus [14 taxones], Ophioceras [7 taxones], Ophiociliomyces [4 taxones], Ophioglossum [5 taxones], Ophionectria [1 taxon], Ophiopogon [3 taxones], Ophiorrhiza [3 taxones], Ophiostoma [5 taxones], Ophiostomella [1 taxon], Ophiurus [4 taxones], Opilia [6 taxones], Oplismenus [89 taxones], Opopanax [2 taxones], Opuntia [112 taxones], Orbignya [16 taxones], Orbilia [16 taxones], Orcadia [1 taxon], Orchis [12 taxones], Oreamnos [3 taxones], Orectochilus [1 taxon], Orectogyrus [1 taxon], Oredoxa [4 taxones], Oreochloa [1 taxon], Oreocnide [1 taxon], Oreodoxa [1 taxon], Oreomyrrhis [4 taxones], Oreopanax [11 taxones], Origanum [55 taxones], Orinebius [1 taxon], Orinocoa [1 taxon], Orites [1 taxon], Ormiscodes [1 taxon], Ormocarpum [7 taxones], Ormosia [31 taxones], Ornithidium [1 taxon], Ornithodoros [1 taxon], Ornithogalum [104 taxones], Ornithoglossum [2 taxones], Ornithopus [1 taxon], Orobanche [105 taxones], Orobus [1 taxon], Orocharis [1 taxon], Orontium [1 taxon], Oropetium [3 taxones], Oropogon [1 taxon], Oroxylon [2 taxones], Oroxylum [6 taxones], Orromyces [1 taxon], Orthaga [1 taxon], Orthantha [2 taxones], Orthezia [18 taxones], Orthilia [2 taxones], Orthobellus [2 taxones], Orthoclada [2 taxones], Orthodon [1 taxon], Orthopappus [1 taxon], Orthosanthus [5 taxones], Orthosiphon [6 taxones], Orthrosanthus [4 taxones], Oryctanthus [7 taxones], Oryctes [2 taxones], Oryctolagus [3247 taxones], Oryza [1064 taxones], Oryzopsis [24 taxones], Osbeckia [6 taxones], Osmanthus [103 taxones], Osmia [1 taxon], Osmorhiza [28 taxones], Osmoxylon [3 taxones], Osmunda [17 taxones], Osphronemus [1 taxon], Ossaea [8 taxones], Osteospermum [12 taxones], Ostodes [1 taxon], Ostrinia [1 taxon], Ostrya [18 taxones], Ostryoderris [4 taxones], Oswaldoa [21 taxones], Osyridocarpos [36 taxones], Osyris [57 taxones], Othius [1 taxon], Othonna [6 taxones], Otiorhynchus [1 taxon], Otites [15 taxones], Otochilus [1 taxon], Otophora [1 taxon], Otospermum [2 taxones], Otthia [1 taxon], Ottochloa [4 taxones], Otyria [1 taxon], Oudemansiella [10 taxones], Ougeinia [12 taxones], Ouratea [76 taxones], Ourisia [12 taxones], Ovidia [1 taxon], Ovis [2511 taxones], Ovulariopsis [3 taxones], Oxalis [132 taxones], Oxandra [75 taxones], Oxya [1 taxon], Oxyanthus [32 taxones], Oxybaphus [3 taxones], Oxycoccus [2 taxones], Oxydothis [3 taxones], Oxygonum [2 taxones], Oxypetalum [5 taxones], Oxyria [9 taxones], Oxyspora [2 taxones], Oxystelma [3 taxones], Oxytellus [1 taxon], Oxytenanthera [4 taxones], Oxytropis [29 taxones], Oyedaea [22 taxones]