General: Pricklyleaf Dogweed (Thymophylla acerosa) is a low-growing, upright subshrub with thin, narrow (unlobed) green leaves and yellow daisy flowers that appear in the spring and fall. The solitary flowers stand atop a short flowering stalk. Often this compact little shrub stands out as bright green when everything else is brown. After blooming, the leaves fall off and the plant seems to disappear.

Pricklyleaf Dogweed is an uncommon component of vegetation communities on well-drained sandy, gravelly, and rocky soils along washes and on upper bajadas and moderate slopes into the lower mountains in the Lower Sonoran (Creosote-Bursage Flats) and Upper Sonoran (Mojave Desert Scrub and Pinyon-Juniper Woodland) life zones. This species is more common in the Sonoran Desert.

Family: Sunflower (Asteraceae).

Other Names: Dyssodia acerosa. Prickly-leaf Dogweed, Texas Dogweed, Shrubby Dogweed, Prickleleaf Dogweed, Fetid Marigold, Scrubby Dogweed.

Plant Form: Small, upright shrub emerging from a single, stout taproot; stems sweep out and upward.

Height: Usually about shin high, but to about 12 inches.

Bark: Light brown.

Stems: Thin, bending upward, branched from base.

Leaves: Thread-like and dark green, 10–18 mm. Linear, unlobed.

Flowers: Peduncle: short (0-10 mm). Inflorescence: single composite flowerhead nestled among the uppermost the leafy parts. Phyllaries gland dotted. Flowers: disk and ray flowers, yellow, usually about 1/2-inch diameter. Ray florets 7–8. Disc florets 18–25.

Calyculi: 5 lance-linear bractlets at base of flowerhead, lengths about 1/2 of phyllaries.

Habitat: Dry, well-drained sandy, gravelly, and rocky soils on upper bajadas and moderate slopes in the lower mountains, especially on limestone and gypsum soils.

Elevation: About 3,000 to 6,000 feet.

Distribution: Nevada to Texas and south into Mexico.

Comments: Another abundant species of Thymophylla occurs in the Las Vegas area. Fiveneedle Pricklyleaf (Thymophylla pentachaeta) looks similar, but the leaf blades are lobed and the flowers stand atop a long stalk (20-100 mm). At a casual glance, our common species appears to have non-lobed leaves because the leaves are so deeply incised as to appear as individual, non-lobed leaves. Careful inspection of the leaves with a hand-lens is helpful to confirm the rare species, especially when the flower stalk is short.

Dogweeds are strong-scented plants.