Bolander's Yampah, Olasi, Mountain False Caraway: Perideridia bolanderi spp. bolanderi - Petioles and base of scape at least 2 mm thick. Main leaves several times pinnately dissected into numerous segments of unequal lengths and usually over 1 mm wide. Fruit oblong, 3-5 mm long.
Red Root Yampah: Perideridia erythrorhiza -
Common Yampah, Gairdner's Yampah, Gardner's Yampah, Mountain Yampah, Wesern False Caraway: Perideridia montana (Synonyms: Atenia montana, Carum garrettii, Carum montanum, Perideridia gairdneri, Perideridia gairdneri ssp. borealis, Perideridia gairdneri var. montana, Perideridia lemmonii) - Note: This is considered to be Perideridia gairdneri in Oregon. Petioles and base of scape less than 2 mm thick at the base. Main leaves once divided or partially twice pinnately or ternately divided into narrow segments of relatively equal length and less than 2 mm wide. Petals 5- or 7-veined. Fruits spherical or nearly so, 2-3.5 mm in diameter.
Howell's False Caraway: Periderida howellii - A species of the southern Oregon Cascades and Siskiyou Mts., it may be found eastward into south-central Klamath County.
Oregon Yampah, Eppaw: Perideridia oregana (Synonyms: Atenia oregana, Carum oregana) - Petioles and base of scape less than 2 mm thick at the base. Main leaves once divided or partially twice pinnately or ternately divided into narrow segments of relatively equal length and less than 2 mm wide. Found mostly west of the Cascades, but occasionally found eastward to Crook and Klmath Counties in Oregon.