Stemless Four-nerved Daisy

Tetraneuris acaulis is a highly variable perennial plant that grows from a large, coarse taproot. It may be moderate in size or an extremely short herbaceous plant, 2 centimeters to over 30 centimeters in height when flowering. The plants lack stems with all the clustered leaves growing directly from the base of the plant at ground level (basal leaves). The leaves are tightly packed and may be spoon shaped (spatulate) or like a spear head with the widest part in the end third (oblanceolate), sometimes narrowly so (linear-oblanceolate). The leaf edges lack teeth or divisions and may either be hairy or smooth. Each flowering stem has a single flower head at the end, though very rarely a stem may have two flower heads on a single stem. The flowering stem does not have any leaves (a scape) and each plant may grow between one and thirty-five flowering stems, but occasionally a plant may produce as many as sixty. They are also quite variable in the length, ranging from 0.5 to 30 centimetres (0.2 to 10 inches). The flowering head will have a large number of small disc flowers, ranging from twenty-five to over two-hundred. The ray flowers at the edge of the flowering head usually number from eight to fifteen, but may occasionally number as many as twenty-one. The petals (ligules) are showy, 5–20 mm (1⁄4–3⁄4 in) long and fairly wide, 3–8 mm (1⁄8–5⁄16 in). …

This species is very widespread in the United States from Texas and California in the south to Idaho and North Dakota. It is found east of the Rocky Mountains on in the western part of the Great Plains in the northern panhandle of Texas and the westernmost counties of Oklahoma, Kansas, Nebraska, South Dakota, and North Dakota. It is found throughout the Rocky Mountain states of Montana, Wyoming, and Colorado as well as almost all of New Mexico, but is only found in the southeast corner of Idaho. It also grows in the northern half of Arizona, the eastern half of Nevada, and the desert county of San Bernardino in California. In Canada it is found in the prairie provinces of Alberta and Saskatchewan. In Saskatchewan a single colony of the plant, apparently not reproducing, is found on the Missouri Coteau 11–12 kilometers south of Mortlach. In Alberta it is found in the Writing-on-Stone Provincial Park. It grows in a variety of habitat types in foothills and subalpine regions, and high prairie, badlands, and plains.

In an experiment marking individual native bees at nuseries carrying native plants in California, it was found that the bees made the choice to revisit the blooms of Tetraneuris acaulis at a higher than expected rates. The conservation non-profit NatureServe evaluated this species in 2016 and found it to be "globally secure" (G5), a conservation status meaning it is common and widespread without any longterm threats or significant population declines. At the state and proviencial level they evaluated it as "secure" (S5) in Utah and Wyoming and "apparently secure" (S4) in Montana. The species is vulnerable (S3) in Alberta and Nevada and "imperiled" (S2) in Saskatchewan. It has not been evaluated at the state or provincial level in the rest of its range.

Tetraneuris acaulis has been used as a traditional medicinal plant. The Hopi used a poultice of the plant to relieve hip and back pain in pregnant women, and to make a stimulating drink.

Cultivation. Stemless four-nerve daisies are grown by gardeners in rock gardens, including areas beyond its native distribution. It is also grown in areas where water use is a concern due to its very low water requirements. To keep plants compact growers plant them in lean soils without much organic material, though the species is not sensitive about soil requirements. They require full sun, with a dry slope being ideal. The salt tolerance of a cultivated selection of Tetraneuris acaulis var. arizonica was tested at Utah State University and found to be very high in comparison with many other cultivated plants. In cultivation stemless four-nerve daisy may bloom in late spring or early summer. The foliage is aromatic. It is winter hardy in USDA zones 4–8, temperatures as cold as −35 °C (−31 °F). The seeds have very little to no requirement for cold stratification to germinate. An experiment found 100% germination in 3–5 days at a temperature of 21 °C (70 °F). However, it does not reproduce from seed very readily in a garden setting, limiting its spread in formal plantings.

The first scientific description of part of what was later classified as Tetraneuris acaulis was by the botanist Frederick Pursh in 1813. He described a species he named Gaillardia acaulis, which as of 2024 is regarded as a synonym of the botanical variety Tetraneuris acaulis var. acaulis. The accepted description as Tetraneuris acaulis was published by Edward Lee Greene in 1898. Due to the variability of the species 32 species that are now regarded as synonyms of one of the four accepted varieties have been described.