Olasi, Bolander's Yampah, Mountain False Caraway: Perideridia bolanderi ssp. 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, Western Yampah: Perideridia erythrorhiza -
Common Yampah, Gairdner's Yampah,Gardner's Yampah, Squawroot, Western False Caraway, Yampah: Perideridia gairdneri ssp. borealis (Synonyms: Atenia montana, Carum montanum, Perideridia montana) - 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, Howell's Yampah: Perideridia howellii - A species of the southern Oregon Cascades and Siskiyou Mts., it may be found eastward into south-central Klamath County.
Tuni, Lemmon's False Caraway, Lemmon's Yampah: Perideridia lemmonii - at Beatty Butte SE OR - Petioles and base of scape less than 2 mm thick at the base. Main leaves once pinnately or ternately divided into narrow segments of relatively equal length less than 2 mm wide. Petals only with a single, unbranched midvein. Fruit oblong, elliptic or occasionally orbicular, 3-4.5 mm long.
Eppaw, Oregon Yampah, Squaw-potato: 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.