Pl. Hartw., 301. 1849.
Plants 8–40 cm; herbage glabrous or sparsely to densely hairy. Stems erect. Leaves 2–10 cm; leaflets 5–9, blade oblong, ovate, lanceolate, or linear-lanceolate, margins entire or shallowly 2-lobed to deeply 3-lobed. Flowers bowl- to bell-shaped; sepals accrescent or not, lanceolate, ovate, or lanceolate-ovate, 4–8 mm; petals white or cream (sometimes cream basally, aging or drying pink or lilac), obovate, obovate-cuneate, or obcordate, 8–16 mm, 1–1.5 times as long as wide, 1.25–2.1 times longer than sepals, apex usually emarginate, sometimes truncate; filaments 3–6 mm; anthers 1–2 mm; style 2–6 mm. Nutlets gray or dark brown, 3–4 mm, tuberculate or not, sometimes ridged, tubercles gray or dark brown, relatively low and wide. 2n = 10.
Subspecies 4 (4 in the flora).
Subspecies gracilis and parishii, previously in Limnanthes gracilis, are more closely related to subsp. alba than they are to each other. The genetic distance between them and other subspecies of L. alba is sufficient that an argument could be made for recognizing both parishii and gracilis as species (R. V. Kesseli, pers. comm.).
|1||Herbage sparsely to densely hairy; sepals densely hairy; petals 10.5-16 mm.||Limnanthes alba subsp. alba|
|1||Herbage glabrous; sepals glabrous or sparsely hairy; petals 8-15 mm||> 2|
|2||Petals 8-10 mm, 1 times as long as wide, obovate; styles 2-3 mm; San Diego County.||Limnanthes alba subsp. parishii|
|2||Petals (8-)12-15 mm, 1-1.3 times as long as wide, obcordate or obovate; styles 3-4 mm; central Sierra Nevada to southern Oregon||> 3|
|3||Leaflet blade narrowly oblong; petals cream, aging or drying lilac, obcordate, sparsely hairy (hairs long).||Limnanthes alba subsp. versicolor|
|3||Leaflet blade ovate to linear-lanceolate; petals usually white, sometimes cream basally, aging or drying pink, obovate, glabrous.||Limnanthes alba subsp. gracilis|