Torrey's desert-dandelion

Malacothrix torreyi A.Gray

Malacothrix torreyi, known as Torrey's desert-dandelion, is an annual plant in the Asteraceae family. It is native to the western United States, including Oregon, Colorado, Wyoming, Montana, Utah, California, Arizona, Nevada, and Idaho. Described by A. Gray in 1874, the species is characterized by its erect to ascending stems, pinnately lobed leaves, and yellow corollas. The plant has a height range of 5–40 cm and is often stipitate-glandular. It produces 58–93 florets and has distinctive cypselae with prominent ribs.

Description

Malacothrix torreyi is an annual herb with 1–5 stems that are 10–25 cm tall, though occasionally reaching 40 cm. The stems are branched from the base and distally, with sparse foliage. Proximal leaves are obovate to oblong, pinnately lobed, and glabrous or sparsely arachnose. Distal leaves are smaller, linear to elliptic, and may be entire or dentate. The involucres are campanulate, 8–14 mm in length, with 12–20 phyllaries. The calyculi consist of 8–12 lanceolate bractlets with hyaline margins. The yellow corollas measure 14–20 mm, with outer ligules exserted 7–10 mm. Cypselae are 2.5–4 mm long, with 5 prominent ribs, and the pappus consists of 12–15 blunt teeth and 0–6 bristles. The species has a chromosome count of 2n = 14.