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  Accurate identification of the several dozen species of Lomatium is, according to Intermountain Flora, "notoriously difficult....  Some species are highly variable...." Both fruits and flowers are often necessary for identification.  Intermountain Flora further observes that "the distinction between Cymopterus and Lomatium is subject to failure". Ordinarily one or more of the Cymopterus dorsal seed ribs have wings; Lomatium seed ribs do not have wings"Cymopterus newberryi completely bridges the difference.  In this species the dorsal wings vary from nearly or fully as large as the lateral ones to poorly developed or even obsolete".

   "Loma" is Greek for "border" and refers to the small wings of the fruit.  The genus was named by Constantine Rafinesque in 1819.

Lomatium triternatum

Lomatium triternatum
Apiaceae (Parsley Family)

Foothills. Sagebrush, openings, woodlands. Spring.
Prater Ridge Trail, Mesa Verde National Park, May 2, 2006.

Lomatium triternatum leaves are borne on narrow stems and are long, thin, and divided in threes, usually three times.  A leafless flower stalk is topped by a tight cluster of glowing yellow flowers which eventually spread very wide -- as shown in the photographs below.  Each plant usually produces one, six-to-twelve inch flower stalk with a three or four inch flower head. The plant is eye-catching because it commonly grows scattered in large patches.  

"Triternatum", means three times ternate, i.e., leaves are split three times and then again three times and then again  --  although you will notice that the plant sometimes splits into threes only twice.

The plant was first collected by Meriwether Lewis on the Lewis and Clark Expedition in present day Idaho, probably in 1806.  Frederick Pursh named it Seseli triternatum in his Flora Americae Septentrionalis in 1814.  It has gone through numerous name changes and the presently accepted name of Lomatium triternatum was given by John Coulter in 1900.

Lomatium triternatum

Lomatium triternatum

Lomatium triternatum
Apiaceae (Parsley Family)

Foothills. Sagebrush, openings, woodlands. Spring.
Prater Ridge Trail, Mesa Verde National Park, May 2, 2006 and Narraguinnep Natural Area, May 11, 2009,

Rays elongate with age and give a very different appearance to the flower head.

Lomatium triternatum
Apiaceae (Parsley Family)

Foothills. Sagebrush, openings, woodlands. Spring.
Mesa Verde National Park, near Farview, May 8, 2001.

"Lomatium" is Greek for a "fringe" or "border" and refers to the winged edge of the seed (very light color in the photo).

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Eradicated
Questionable presence

Range map for Lomatium triternatum