Creeping Woodsorrel, Creeping Wood-sorrel, Creeping Yellow Wood Sorrel, Creeping Yellow Wood-sorrel: Oxalis corniculata (Synonyms: Acetosella corniculata, Oxalis corniculata var. atropurpurea, Oxalis corniculata var. langloisii, Oxalis corniculata var. lupulina, Oxalis corniculata var. macrophylla, Oxalis corniculata var. minor, Oxalis corniculata var. reptans, Oxalis corniculata var. villosa, Oxalis corniculata var. viscidula, Oxalis langloisii, Oxalis pusilla, Oxalis repens, Oxalis villosa, Oxalis violacea, Xanthoxalis corniculata, Xanthoxalis corniculata var. atropurpurea, Xanthoxalis langloisii, Xanthoxalis repens) -
Graygreen Sorrel, Slender Yellow Woodsorrel, Southern Yellow Wood Sorrel: Oxalis dillenii (Synonyms: Oxalis brittoniae, Oxalis corniculata var. dillenii, Oxalis dillenii ssp. filipes, Oxalis dillenii var. radicans, Oxalis filipes, Oxalis florida, Oxalis florida ssp. prostrata, Oxalis florida var. filipes, Oxalis prostrata, Oxalis rupestris, Oxalis stricta, Xanthoxalis brittoniae, Xanthoxalis dillenii, Xanthoxalis filipes, Xanthoxalis florida) -
Oregon Wood Sorrel, Oregon Wood-sorrel, Redwood Sorrel, Redwood-sorrel, Sour Grass, Western Wood-sorrel: Oxalis oregana (Synonyms: Oxalis acetosella ssp. oregana, Oxalis oregana var. oregana, Oxalis oregana var. smallii) - Flower scapes with only 1 flower. Petals 13-20 mm long.
Common Yellow Oxalis, Upright Yellow Wood-sorrel, Yellow Wood-sorrel: Oxalis stricta (Synonyms: Ceratoxalis coloradensis, Ceratoxalis cymosa, Oxalis bushii, Oxalis coloradensis, Oxalis cymosa, Oxalis europaea, Oxalis europaea var. bushii, Oxalis europaea var. rufa, Oxalis fontana, Oxalis fontana var. bushii, Oxalis interior, Oxalis rufa, Oxalis stricta var. decumbens, Oxalis stricta var. piletocarpa, Oxalis stricta var. rufa, Oxalis stricta var. villicaulis, Xanthoxalis bushii, Xanthoxalis coloradensis, Xanthoxalis cymosa, Xanthoxalis dillenii var. piletocarpa, Xanthoxalis interior, Xanthoxalis rufa, Xanthoxalis stricta, Xanthoxalis stricta var. piletocarpa) -
Suksdorf Woodsorrel, Suksdorf Wood-sorrel, Suksdorf's Oxalis, Western Yellow Oxalis, Western Yellow Wood-sorrel: Oxalis suksdorfii (Synonyms: Oxalis corniculata var. macrantha, Oxalis macrantha, Oxalis pumila, Oxalis recurva var. macrantha, Xanthoxalis macrantha, Xanthoxalis suksdorfii) -
Great Oxalis, Great Wood-sorrel, Threeleaf Wood-sorrel, Trillium-leaved Oxalis, Trillium-leaf Wood Sorrel, Trillium-leaf Wood-sorrel: Oxalis trilliifolia (Synonym: Hesperoxalis trilliifolia) - Flower scapes with 2 to several flowers. Petals about 10 mm long.