Plants mostly 20-100 cm. Leaves: basal (rosette) leaves mostly 3-10 × 1-5 cm; petioles 1-4 cm; blades ovate, usually pedately to pinnately lobed (cauline leaves in vernal forms much reduced; autumnal forms often leafy throughout and cauline leaves not much reduced). Heads borne singly. Peduncles 10-30 cm (vernal forms, often shorter on autumnal forms). Involucres hemispheric (vernal forms), mostly 5-10 × 10-25 mm. Phyllaries mostly 21-34, floccose-tomentose. Rays (vernal forms) mostly 34-55; laminae linear-oblanceolate, mostly 10-20 × 5 mm, apices moderately to deeply 3-toothed. Disc florets (vernal forms) 100+; corollas 4 mm, tubes 1 mm, lobes 0.25 mm; style-branch apices truncate to slightly rounded. Cypselae 4 mm. 2n = 32. Flowering Mar-Nov (depending on rains). Stony slopes, mesas, and sandy plains; 100-2000 m; Ariz., Calif., Nev., N.Mex., Tex., Utah; Mexico (Aguascalientes, Chihuahua, Coahuila, Durango, Sonora). Baileya multiradiata is an attractive and bountiful wild flower over a large part of the desert Southwest. It has been touted as a promising plant for landscaping, and research on its nursery production has begun (D. J. Cotter et al. 1980, 1982).
Both Baileya multiradiata and B. pleniradiata produce an antineoplastic pseudoguaianolide, radiatin, which might prove useful in cancer therapy (J. J. Einck et al. 1978). In addition, the antibiotic sesquiterpene lactone, baileyolin, from B. multiradiata inhibits tumor formation (X. A. Dominguez et al. 1977).
Baileya multiradiata is reportedly toxic to livestock, especially to sheep and goats, where losses as high as 25% have been reported on overgrazed rangeland in Texas (D. W. Hill et al. 1979, 1980). Cattle and horses seem to be unaffected, or at least poisoning of these animals has gone unreported. The chemical agent responsible is believed to be hymenoxon, a sesquiterpene lactone originally found in the genus Hymenoxys, where it is also toxic.
The poorly known desert marigold moth, Schinia minima (Grote), appears to be endemic on Baileya multiradiata, using the heads of this species for its larval development (T. G. Myles and B. F. Binder 1990).
The autumnal blossoms of Baileya multiradiata, with smaller heads, fewer rays, and shorter peduncles, greatly resemble those of B. pleniradiata. This has caused much confusion in the distinction between these two species. The shape of the style apex is a useful character to distinguish between fall-blooming specimens.
FNA 2006, Wiggins 1964, Kearney and Peebles 1969
Duration: Perennial Nativity: Native Lifeform: Forb/Herb General: Annual or short lived perennial herb, 20-40 cm tall; stems decumbent to ascending, branching at base, leafy on lower portions only; herbage floccose-wooly. Leaves: Basal leaves are petiolate, 3-lobed, and 3-5 cm long; cauline leaves are alternate, sessile, entire, spatulate, and 2-4 cm long; all leaves densely white-wooly. Flowers: Flower heads showy, radiate, 4-5 cm wide including rays, and solitary on long peduncles,10-30 cm long, which raise the flower heads well above the foliage; involucre (the ring of bracts surrounding the flower head) hemispheric, 7-8 mm high, 10-15 mm broad, the bracts (phyllaries) linear-lanceolate, 6 mm long, lanate; rays 35-55, bright yellow, the corolla lamina (ray petal) 2 cm long, its apex conspicuously 3-toothed; discs 100+, the corollas yellow. Fruits: Achenes short-cylindric, 3-4 mm long, evenly striate, without pappus. Ecology: Found on arroyo bottoms, outwash slopes, sandy plains and roadsides, below 5,000 ft (1524 m); flowers March-October. Distribution: s CA, s NV, s UT, southeast through AZ, NM and sw TX; south to c MEX. Notes: A distinctive biennial common in most deserts of the southwest and quite visible lining the sides of highways in the early spring. It is identified by its gray-green foliage; the soft, woolly leaves deeply 3-lobed and mostly condensed to the base; multiple, erect, nearly leafless flowering stalks bearing terminal showy flower heads with many large, yellow, 3-lobed rays. Not always readily distinguishable from B. pleniradiata; that species has leaves higher up the stems, sometimes to the apex; shorter peduncles (< 12 cm); and acute style branches. B. multiradiata has leaves concentrated at the bottom of the stems; long peduncles (10-30 cm); and truncate or rounded style branches. Ethnobotany: Rubbed under the arms as a deodorant; mixed with clay and used in making adobes and plaster. Etymology: Baileya is named for Jacob Whitman Bailey (1811-1857) an early American microscopist; multiradiata refers to the many ray flowers per flower head. Synonyms: None Editor: SBuckley 2010, FSCoburn 2014, AHazelton 2015