Members of the genus Psathyrotes are commonly called turtlebacks because they form rounded mounds of leaves that resemble a desert tortoise shell in size and shape. The most common is velvet turtleback (Psathyrotes ramosissima). I found another more widely distributed, but less commmon turtleback (Psathyrotes annua or annual turtleback) while exploring Quartz Mountain in Central Nevada last October. As the name suggests, annual turtleback is an annual, while velvet turtleback is an annual or perennial. The leaves of annual turtleback are less woolly than velvet turtleback and its phyllaries (head bracts) are erect and do not recurve as do those of velvet turtleback.
Annual turtleback branches are numerous, low and spreading or decumbent. The hairy stems are often purplish in color.
The fan-shaped leaves of annual turtleback are alternate, petioled, and have wavy or toothed edges. The leaves appear greyish or whitish because of abundant hairs. The foliage gives off a turpentine odor when crushed.
A member of the Sunflower Family (Asteraceae), the annual turtleback flower head is composed of only yellow disk flowers that turn purplish with age. The single flowers arise from the leaf axils and are held erect just above the leaves.
The fruits are hairy achenes topped by many white to reddish bristles.
This annual native can be found in dry, sandy (often alkaline) desert and scrub habitats below 6,000 feet in California, Idaho, Nevada, Utah and Arizona.
Annual psathyrotes is another common name for P annua. The genus designation, Psathyrotes, comes from the Greek work psathurotes, meaning brittleness, and refers to the stems. The annual nature of the plant is noted in the species name, annua.