Pilosella officinarum

Native

Dry. Pastures, fields, roadsides, lawns, disturbed sites. Full sun. Sandy or gravelly soil.

May to August

Yellow

4″ to 10″

This is an erect, perennial forb that rises on a rosette of basal leaves and a solitary flowering stalk (scape) from fibrous roots and a long, slender, vertical rhizome. It is usually 4″ to 10″ in height at maturity, though some individuals may be up to 16″ tall. It reproduces mostly by abundant aboveground stems (stolons) that creep along the ground and produce a new plant at the tip. When the daughter plants have been formed, the mother plant dies. It eventually forms a dense mat that crowds out other vegetation.

There are usually 5 to 10 or more basal leaves firmly appressed to the ground. The leaves are ¾″ to 5″ long and ¼″ to ¾″ wide. The leaf blades are elliptic to inversely lance-shaped, unlobed, wedge-shaped at the base and broadly angled at the tip. They are 2 to 4 or more times as long as wide. The upper surface is green with few to many pale, soft, nonglandular, 1 ⁄16″ to ¼″ long hairs, sometimes with a few star-shaped hairs, but otherwise hairless. The lower surface is gray or whitish, densely covered with star-shaped hairs, and sparsely covered with long, soft hairs. The margins are untoothed or nearly untoothed and are sparsely covered with long, soft hairs. Basal leaves are present at flowering time.

There are usually 2 to 6 stolons. The stolons are slender, prostrate, leafy, up to 12″ long, and sometimes branched. They are covered with soft, tangled hairs and soft, straight hairs. They root at the tip and form a rosette of overwintering leaves. The leaves on the stolons are similar to the basal leaves but smaller.

The inflorescence is usually a single flower head at the end of a solitary, unbranched, leafless scape. Rarely there may be 2 or 3 flower heads. The scape is densely covered with star-shaped hairs, unbranched hairs, and gland-tipped hairs. There are numerous soft hairs with dark bases scattered over the entire scape. There are dark, gland-tipped hairs especially dense toward the flower head.

The whorl of bracts at the base of the flower head (involucre) is ¼″ to 7 ⁄16″long and half globe-shaped to inversely cone-shaped. The bracts of the involucre are linear lance-shaped. They are densely covered with star-shaped hairs; with black, broad-based, glandular hairs; and with longer, black-based, nonglandular hairs.

Each flower head has 60 to 120 yellow, 5 ⁄16″ to ½″ long ray florets and no disk florets. The outermost ray florets have a red vertical stripe on the underside.

The fruit is a 1 ⁄32″ to 1 ⁄16″ long, 1 ⁄64″ wide cypsela with 30 or more white bristles attached to the end. It is dispersed by wind.

Taxonomy
Until recently, plants in the genus Pilosella were grouped as a subgenus of Hieracium. Distinct features of the cypsela, absence of hybridization between groups, and, in some species, the presence of runners (stolons) and/or red lines on the lower (abaxial) ligule surface, support the segregation of these species into a separate genus. Many sources, including GRIN, now classify this species as Pilosella officinarum. Most sources, including NCBI, ITIS, and UniProt, continue to classify it as Hieracium pilosella. The Plant List remains above the controversy accepting both names as valid.