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Tetraneuris torreyana
Tetraneuris torreyana.  Synonym: Hymenoxys torreyana(Torrey's Four-nerved Daisy) 
Asteraceae (Sunflower Family)

Semi-desert, foothills. Woodlands, openings, rim-rock. Spring.
Prater Ridge Trail, Mesa Verde National Park, May 16, 2006.

These dainty cousins of the much larger Tetraneuris ivesiana (click to see) spread in colonies and grow from four to eight inches tall. The plant has basal leaves only, no stem leaves, and its leaves can be nearly smooth with glandular dots on the surface (use a hand lens to see) or they can be quite hairy with long twisting hairs. In the Four Corners area, these plants are most common in the lower Ponderosa zone along rim rock that is moist in the spring.

Tetraneuris torreyana
Tetraneuris torreyana.  Synonym: Hymenoxys torreyana.  (Torrey's Four-nerved Daisy)
Asteraceae (Sunflower Family)

Semi-desert, foothills. Woodlands, openings, rim-rock. Spring.
Prater Ridge Trail, Mesa Verde National Park, May 16, 2006.

Tetraneuris torreyana was first collected by Thomas Nuttall near the upper North Platte in the 1834 and he named the plant Actinella torreyana.  Edward Greene renamed it Tetraneuris torreyana in 1898.  "Tetraneuris" is Greek for "four nerves", referring to the nerves on the ray flowers. John Torrey was the most prominent American botanist of the early and mid-1800s and was the teacher of Asa Gray, with whom he co-authored many botanical books. (More biographical information about Torrey.)

 

Tetraneuris torreyana
Tetraneuris torreyana.  Synonym: Hymenoxys torreyana.  (Torrey's Four-nerved Daisy)
Asteraceae (Sunflower Family)

Semi-desert, foothills. Woodlands, openings, rim-rock. Spring.
Gateway area, May 11, 2012.

In the words of Colorado flora expert, William Weber: "leaf bases [are] set in a conspicuous tuft of long white hairs" and this separates T. torreyana from T. acaulis. However, other botanical experts (e.g., Cronquist in Intermountain Flora) do not agree and actually indicate that T. acaulis has leaf bases set in a tuft of hairs. Cronquist indicates that the main separating physical feature is the shape and texture of the phyllaries.

After comparing eight experts' keys describing T. torreyana and T. acaulis, I can only conclude that the experts do not agree on the characteristics that separate the two, and that the two species are extremely similar.  See further discussion on my page about T. acaulis.

Tetraneuris torreyana

Tetraneuris torreyana

Tetraneuris torreyana.  Synonym: Hymenoxys torreyana.  (Torrey's Four-nerved Daisy)
Asteraceae (Sunflower Family)

Semi-desert, foothills. Woodlands, openings, rim-rock. Spring.
Prater Ridge Trail, Mesa Verde National Park, May 16, 2006.

Flower stems and red-tinged phyllaries are quite hairy.

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 Tetraneuris torreyana