Carnegiea gigantea, Giant Saguaro

Southwest Desert Flora

Home to the plants of the Sonoran, Chihuahuan and Mojave Deserts

Cirsium ochrocentrum, Yellowspine Thistle

Senecio flaccidus, Threadleaf Groundsel

Threadleaf Groundsel, Senecio flaccidus Threadleaf Groundsel, Senecio flaccidus Threadleaf Groundsel, Senecio flaccidus Threadleaf Groundsel, Senecio flaccidus

Scientific Name: Senecio flaccidus
Common Name: Threadleaf Groundsel

Also Called: Thread-Leaf Ragwort, Threadleaf Ragwort, Douglas Senecio, Threadleaf Groundsel (Spanish: Hierba Ceniza)

Family: Asteraceae, Sunflower Family

Synonyms: (Senecio douglasii, Senecio longilobus)

Status: Native

Duration: Perennial

Size: 1 to 4 feet (40-120 cm) or so.

Growth Form: Forb/herb, subshrub; plants upright (erect); woody bases; herbage tomentose with white hairs, sometimes unevenly glabrescent.

Leaves: Green; leaves arranged alternately along stems; leaves linear to filiform or pinnatifid.

Flower Color: Yellow; large and showy; flower heads on tips of branches, 1 or many in clusters; flower head with both ray and disk florets; fruit is a cypsela.

Flowering Season: March and April to July and August; year-round with sufficient rainfall; April and May to August and September in Texas.

Elevation: 2,500 to 7,500 feet (762-2,286 m).

Habitat Preferences: dry plains, slopes, mesas, and along washes.

Recorded Range: Threadleaf Groundsel is found mostly in the southwestern United States in AZ, CO, NM, NV, OK, TX, UT. This variety is also native to central and northern Mexico.

North America & US County Distribution Map for Senecio flaccidus.

North America species range map for Threadleaf Groundsel:

North America species range map for Threadleaf Ragwort, Senecio flaccidus var. flaccidus: Click image for full size map.
Click image for full size map

U.S. Weed Information: Unknown
Invasive/Noxious Weed Information: Unknown
Wetland Indicator: Unknown
Threatened/Endangered Information: Unknown

Genus Information: In North America there are 71 species for Senecio. Worldwide, The Plant List includes 1,587 accepted species names and a further 871 scientific names of infraspecific rank for Senecio.

The genus Senecio was published in 1753 by Carl Linnaeus, (1707-1778).

In the Southwestern United States: Arizona has 13 species of Senecio, California has 25 species, Nevada has 15 species, New Mexico has 22 species, Texas has 9 species, Utah has 18 species. Data approximate and subject to revision.

According to the Flora of North America, Senecio flaccidus var. flaccidus intergrades at least to some extent with var. monoensis in areas of overlapping ranges; a case could be made for treating the two as distinct species, as done by A. Cronquist (1994). Arizona varieties overlap.

Comments: The flowers of Threadleaf Groundsel and it's sub-species are too similar to use as a field identification characteristic.

Threadleaf Ragwort, variety flaccidus is a common large subshrub similar in appearance to Smooth Threadleaf Ragwort, Senecio flaccidus var. monoensis, but may be differentiated in the field where varieties overlap by its silvery or canescent woolly appearance and comb-like pinnatifid leaves.

In Southwest Desert Flora also see Lemmon's Ragwort, Senecio lemmonii, Smooth Threadleaf Ragwort, Senecio flaccidus var. monoensis, Threadleaf Ragwort, Senecio flaccidus var. flaccidus and Common Groundsel, Senecio vulgaris.

The genus Senecio is known to contain alkaloids which may cause liver damage in livestock.

Importance to Wildlife, Birds and Livestock
Senecio flaccidus has large showy daisy-like flowers and the flowers and their seeds and plants may be visited by hummingbirds and/or small mammals including rodents and granivorous birds in search of food, nectar, shelter and protection through cover.

Beneficial Value to Butterflies, Bees and Insects
Senecio flaccidus has large showy daisy-like flowers and the flowers and their plants may be visited by butterflies, moths, native bees and other insects in search of nectar and/or other food.

The genus “Senecio” (Sene'cio:) from senex, "old man," referring to the gray hairs on the seeds.

The genus Senecio was published in 1753 by Carl Linnaeus, (1707-1778).

The species epithet flaccidus (flac'cidus:) is Latin for flaccid.

The taxon Senecio flaccidus was published in 1860 in Bonplandia.


Date Profile Completed: 10/27/2020;
Arizona Flora, Kearney, Thomas H., Peebles, Robert H., 1960, University of California Press, Berkley and Los Angeles, as Senecio longilobus.
U.S. Dept. of Agriculture, Natural Resources Conservation Service on-line database and USGS ITIS search; accessed 10/25/2020.
The Plant List (2013). Version 1.1. Published on the Internet;; accessed 10/25/2020.
Theodore M. Barkley, FNA|Family List|FNA Vol. 20|Asteraceae, Senecio, 25. Senecio flaccidus Lessing, Linnaea. 5: 161. 1830.; Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 16+ vols. New York and Oxford
Debra K. Trock 2012, Senecio flaccidus, in Jepson Flora Project (eds.) Jepson eFlora, /eflora/eflora_display.php?tid=4736, accessed on October 28, 2020.
FNA 2006, Kearney and Peebles 1969, McDougall 1973, Heil et al. 2013, Allred and Ivey 2012, Correll and Johnston 1970; Editors: L.Crumbacher 2011, A.Hazelton 2017; from SEINet Field Guide, on-line; accessed 10/28/2020.
Wikipedia contributors, 'Senecio flaccidus', Wikipedia, The Free Encyclopedia, 18 September 2020, 20:16 UTC, [accessed 28 October 2020]
Native Plant Information Network, NPIN (2013). Published on the Internet [accessed: 10/28/2020]. Lady Bird Johnson Wildflower Center at The University of Texas, Austin, TX.
Seiler, John, Peterson, John, North American species range map courtesy of Virginia Tech, Dept. of Forest Resources & Environmental Conservation
SEINet synonyms, scientific names, geographic locations, general information.
Etymology:Michael L. Charters California Plant Names: Latin and Greek Meanings and Derivations; A Dictionary of Botanical and Biographical Etymology - (accessed 10/24/2020)
IPNI (2020). International Plant Names Index. Published on the Internet, The Royal Botanic Gardens, Kew, Harvard University Herbaria & Libraries and Australian National Botanic Gardens. [Retrieved 25 October 2020].