Scattered areas across all the western states; absent from Texas
Ponds, stream margins, boggy ground, from sea level to 6,500 feet
Blades are ovate to broadly lanceolate, up to 15 cm long, on thick stalks of up to 30 cm. Leaf bases may be shallowly lobed
March to September
Flowers of alisma triviale are formed of three green sepals with irregular brownish margins, and three unnotched white (occasionally pale pink) petals, yellow at the base, around 6 mm in length. At the center are six greenish stamens, radiating from a central, flattish disc of 15 to 20 pistils. The inflorescence is a branched cluster, held well above the leaves, and extending up to 15 inches at the top of the leafless stalk. Branches in the inflorescence are subtended by bracts, and pedicels are ascending.
The hairless leaves grow only at the base; they have long stalks, of different lengths, and shiny surfaces crossed by lengthwise veins and fainter transverse veins. This species is most common in central Arizona and the three Pacific states.