Evening Primroses: The Genera Camissonia, Chylismia, Chylismiella, Eremothera and Taraxia - 4 sepals and petals. Sepals reflexed at flowering time. Ovary with 4 chambers. Stigma hemispheric or head-like, not 4-lobed.
Fireweed & Broadleaf Willowherb: The Genus Chamerion - Leaves alternate. 4 sepals and petals. Sepals erect or spreading, not reflexed. Hypanthium absent. Ovary with 4 chambers.
Enchanter's Nightshade: Circaea alpina ssp. pacifica (Synonyms: Circaea alpina ssp. alpina, Circaea alpina ssp. pacifica, Circaea alpina var. pacifica, Circaea pacifica) - Sepals and petals both 2. Fruits bur-like, covered with hooked hairs.
Clarkias: The Genus Clarkia - 4 sepals and petals.Sepals reflexed at flowering time. Anthers attached at the base.
Willowherbs & Spike-primroses: The Genus Epilobium - Leaves mostly opposite. 4 sepals and petals. Sepals erect or spreading, not reflexed. Hypanthium present. Ovary with 4 chambers.
Groundsmokes: The Genus Gayophytum - 4 sepals and petals. Ovary with 2 chambers. Hypanthium barely passes the ovary. Flowers minute.
Eastern False Loosestrive, Marsh Seedbox, Marsh Primrose-willow: Ludwigia palustris (Synonyms: Ludwigia palustris var. americana, Ludwigia palustris var. pacifica)
Evening Primroses: The Genus Oenothera - 4 sepals and petals. Sepals reflexed at flowering time. Ovary with 4 chambers. Stigma 4-lobed. Anthers attached at the middle.