Tetraneuris acaulis var. arizonica.  Synonyms: Hymenoxys acaulis var. arizonica. (Stemless Woolly Base, Stemless Four-nerved Daisy)
Asteraceae (Sunflower Family)

Foothills to sub-alpine. Openings. Summer.
Near Lone Mesa State Park, June 15, 2016.

Although Tetraneuris acaulis does grow on the flat, hot, dry soils of Mancos Shale meadows, it thrives when it finds pockets of more moisture on the Shale. In this photograph which looks downhill, we can see that Tetraneuris is very happy in a forty foot long depression in the Mancos Shale.

Tetraneuris acaulis var. arizonica.  Synonyms: Hymenoxys acaulis var. arizonica. (Stemless Woolly Base, Stemless Four-nerved Daisy)
Asteraceae (Sunflower Family)

Foothills to sub-alpine. Openings. Summer.
Lone Mesa State Park, June 7, 2008.

Tetraneuris acaulis var. arizonica. Synonyms: Hymenoxys acaulis var. arizonica (Stemless Woolly Base, Stemless Four-nerved Daisy).
Asteraceae (Sunflower Family)

Foothills to sub-alpine. Openings. Summer. Lone Mesa State Park, June 7, 2008.

Tetraneuris acaulis is short, lovely, and, in the Four Corners area,uncommon but often abundant when you do find it. Stems have no leaves, varying amounts of hair, and often grow in quite noticeable clumps. The plant prefers dry open areas; many of those shown on this page are growing in Mancos Shale.

Tetraneuris acaulis is very similar to Tetraneuris torreyana, but various botanical keys disagree on how to tell them apart. The two are said to differ in the greater number of phyllaries (7-10) versus (4-8), or the hairiness of the leaves, or the venation in the leaves, or, most agreed upon, whether the margins of the phyllaries are thin and paper-like at their edges (Tetraneuris torreyana) or green-red to the edges (Tetraneuris acaulis). After comparing the widely varying and contradictory descriptions of these two species by eight botanical experts, I can only conclude that T. acaulis and T. torreyana are extremely similar  --  perhaps identical.

Their lack of stem leaves separates them from the very similar and common Four Corners taxa, Tetraneuris ivesiana, but these three (and three additional taxa) are so similar that the Utah Flora expert, Stanley Welsh, indicates that they are all varieties fitting under the species name of Hymenoxys acaulis.

Edward Greene named this genus in 1898.  "Tetraneuris" is Greek for "four nerves", referring to the nerves on the ray flower petals, and "acaulis" means "without leaves on the stem".

This species was first collected for science by Bradbury in North Dakota and Pursh named it Gaillardia acaulis in 1814. It has endured dozens of other names. There are at least four varieties of T. acaulis and the names are ascribed to a number of different authors.

Tetraneuris acaulis var. arizonica. Synonyms: Hymenoxys acaulis var. arizonica (Stemless Woolly Base, Stemless Four-nerved Daisy).
Asteraceae (Sunflower Family)

Foothills to sub-alpine. Openings. Summer. Lone Mesa State Park, June 7, 2008 and June 4, 2011 and near Lone Mesa May 10, 2014.

Notice what a great difference there is between the width and length of the yellow rays on the just opening bud in the photograph at top left and those on the fully mature flower heads. Descriptions of plants almost always give you the characteristics of the mature flower.

The second photo at left shows the very hairy phyllaries on the bud of the stemless flowerhead tucked tightly into the leaves.  This, too, can fool you and make identification difficult.  Again, one needs a mature flower. The flower stem on this plant will elongate to about 4 inches. 

Notice also, especially as shown in the third photograph, that the leaves are glandular-punctate; i.e., they are dotted with glandular pits. There are also sometimes long hairs scattered or thickly covering the leaf surface.

A very pleasant fruity fragrance emanates from the flower head, especially from the glandular inner surface of the phyllaries and from the receptacle.

Tetraneuris acaulis var. arizonica. Synonyms: Hymenoxys acaulis var. arizonica (Stemless Woolly Base, Stemless Four-nerved Daisy).
Asteraceae (Sunflower Family)

Foothills to sub-alpine. Openings. Summer. Lone Mesa State Park, June 7, 2008.

The notched petal tips and the over-lapping rows (two or three) of hairy and broadly lanceolate phyllaries are very attractive characteristics.

For many years I had the photographs below labeled as Tetraneuris torreyana. In 2022 John Kartesz indicated, "based on all meaningful reports and publications I've assessed, Tetraneuris torreyana does NOT occur in west-central nor southern Colorado.  Nor does it occur in New Mexico or Arizona.  In fact, all records from southern and central Utah are also incorrect.  All those records are actually based on misidentifications of the extremely variable T. acaulis."

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.

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.)

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.

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 acaulis