Oak stump bonnet cap (see Clustered bonnet)
Oak, Bear (see Oak, Scrub)
Oak, Black Quercus velutina Beech
Oak, Chestnut Quercus prinus Beech
Oak, Chestnut-leaved (see Oak, Chestnut)
Oak, Gray (see Oak, Red)
Oak, Northern Red (see Oak, Red)
Oak, Peach (see Oak, Willow)
Oak, Pin Quercus palustris Beech
Oak, Quercitron (see Oak, Black)
Oak, Red Quercus rubra Beech
Oak, Rock (see Oak, Chestnut)
Oak, Rock Chestnut (see Oak, Chestnut)
Oak, Scrub Quercus ilicifolia Beech
Oak, Spanish (see Oak, Pin)
Oak, Stave (see Oak, White)
Oak, Swamp (see Oak, Pin)
Oak, White Quercus alba Beech
Oak, Willow Quercus phellos Beech
Oak, Yellow (see Oak, Black)
Oats, Wild/ Sessile Bellwort/ Little Merrybells Uvularia sessilifolia Lily
Obediant plant Physostegia virginiana Mint
Oilnut (see Butternut)
Old man of the woods Srobilomyces floccopus Mushrooms With Pores (Polypores)
Old Man's Beard (see Virgin's Bower/ Old Man's Beard)
Oleaster, Autumn (see Olive, Autumn)
Olive, Autumn Eleagnus umbellata Oleaster/Eleagnus
Onion, Nodding Wild Allium cernuum Lily
Orach Atriplex patula Goosefoot
Orange mock oyster (see Nestcap)
Orchid, Rattlesnake Goodyera pubescens Orchid
Osage orange Maclura pomifera Mulberry
Oswego Tea (see Bee-balm/ Oswego tea)
Ox-Eye/ False Sunflower Heliopsis helianthoides Sunflower-Like
Oyster mushroom Pleurotis ostreatus Gilled Mushrooms
Oyster, bitter (see Panellus, luminescent)
Oyster, green (see Oyster, late)
Oyster, Indian (see Oyster, pale)
Oyster, late Panella seratinus Gilled Mushrooms
Oyster, late fall (see Oyster, late)
Oyster, lung (see Oyster, pale)
Oyster, pale Pleurotus pulmonarius Gilled Mushrooms
Oyster, summer (see Oyster, pale)
Eleagnus umbellata
Fraxinus americana
Forsythia suspensa
Syringa vulgaris
Ligustrum vulgare
Ligustrum obtusifolium
Spiranthes cernua
Cypripedum acaule
Goodyera pubescens