Baileya multiradiata Harv. & Gray ex Torr.

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.

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.

Baileya australis Rydberg; B. multiradiata var. nudicaulis A. Gray; B. pleniradiata Harvey & A. Gray var. multiradiata (Harvey & A. Gray) Kearney; B. thurberi Rydberg

Baileya multiradiata has a bioregional distribution in the southwestern part of North America including southern California, Nevada, Arizona, New Mexico and northern Mexico. Preferred habitat is in the elevation bracket from 600 to 1600 meters. Specific widespread occurrence is throughout the Mojave Desert; habitat types include Desert roadsides, flats, washes and hillsides.

Also known as the Desert marigold, this herb is canescent-tomentose, with heights attained to one half meter; this plant is generally branched only at base. Leaves, measuring two to ten centimeters, are mostly basal and on the lower stems. Ray flowers contain 50 to 60 bright yellow florets, while the numerous disc florets are somewhat brownish tinged yellow.

As with all Asteraceae, the center of genetic diversity is in the High Andes, and this species likely migrated northward when the Central American isthmus was formed circa three million years ago, and abandoned its southern ancestors.

Baileya multiradiata Harv. & Gray; Torr. in Emory, Notes Mil. Recon. 144. 1848.
Baileya multiradiata nudicaulis A. Gray, Syn. Fl. N. Am. P: 318. 1884. Baileya pleniradiata multiradiata Kearney, Trans. N. Y. Acad. Sci. 14: 42. 1894.
A floccose biennial; stem 2-3 dm. high, decumbent and branched at the base, leafy only below, densely white-floccose ; basal leaves numerous, spatulate, 3-5 cm. long, the earlier 3-lobed and crenate, the later deeply 3-cleft and lobed, densely white-floccose; lower stemleaves similar or more pinnatifid with obovate divisions, the uppermost entire; heads solitary on long terminal peduncles, which are 1-2 dm. long; involucre hemispheric, 7-8 mm. high, 12-15 mm. broad; bracts 25-35, linear-lanceolate; ligules 35-50, cuneate-oblong, tapering at the base, about 1 cm. long, with 3 broadly ovate teeth at the end, orange, turning paleyellow in age; disk-flowers very numerous, glandular-granuliferous, about 4 mm. long; achenes somewhat angled at the truncate apex, tapering gradually downwards, glandular-granuliferous, almost equally striate-ribbed.
Type locality: Along the [Rio Grande] Del Norte [New Mexico]. Distribution: Western Texas to Nevada and Chihuahua.

Baileya thurberi Rydberg, sp. nov
A biennial or perennial; stem 2-4 dm. high, erect, simple at the base, much branched and leafy above, rather loosely floccose ; branches ascending; leaves, except the uppermost, spatulate or cuneate in outline, 1-3 cm. long, lobed or divided into obovate divisions, densely floccose; peduncles terminating the branches, 5-10 cm. long; involucre hemispheric, 5-6 mm. high, about 1 cm. broad; bracts about 40, linear-lanceolate; ligules 30-40, oblong, abruptly tapering at the base, with 3 rounded-ovate teeth at the apex, about 8 mm. long and 4 mm. wide; disk-flowers numerous; corollas about 3 mm. long, glandular-granulif erous ; achenes about 3 mm. long, scabrous-hispidulous as well as glandular-granuliferous, tapering downwards, the ribs on the angles slightly stronger than the rest.
Type collected along the Pecos [Texas] 1850, Thurber 132 (herb. N. Y. Bot. Gard.). Distribution: Western Texas, New Mexico, and Coahuila.

Baileya multiradiata is a North American species of sun-loving wildflowers native to the deserts of northern Mexico and the Southwestern United States. It has been found in the States of Sonora, Chihuahua, Coahuila, Durango, Aguascalientes, California, Arizona, Nevada, Utah, New Mexico, and Texas.

B. multiradiata is a short-lived perennial to annual that forms a clumping patch of silvery-green foliage, growing to 50 centimetres (20 inches) tall. The leaves are 4–8 cm (1+1⁄2–3+1⁄4 in) long. The many tall, naked stems are each topped with a bright yellow daisy-like flower head about 4–5 cm (1+1⁄2–2 in) wide, with 25–50 ray florets. It blooms from April to October. The seed-like fruit is whitish, with no scales or bristles at the tip.

Although called a desert marigold, it is only a remote relative of the true marigolds of the genus Tagetes.

B. multiradiata growing in the southern Nevada desert