A fine biennial, with stout, leafy stems, from three to six feet high, bearing splendid flowers, over three inches across, with clear yellow petals, fading to pink, and reddish calyx-lobes. The leaves, stems, and buds all downy and the buds erect. The stigma has four, slender lobes, forming a little cross, and the yellow pollen is loosely connected by cobwebby threads, clinging to visiting insects, and is thus carried from flower to flower; the capsule is an inch long. This is much handsomer than the common Evening Primrose, 0. biennis, and especially fine in Yosemite. As the mountain shadows begin to slant across the Valley the blossoms commence to open, until the meadows are thickly strewn with "patens of bright gold." They stay open all night, withering with the noonday sun.
There are several kinds of Lavauxia; low, usually stem-less; leaves mostly from the root; calyx-tube slender; petals four; stamens eight, the alternate ones longer; ovary short, stigma four-cleft; capsule stout, four-angled or winged.