San Patricio Tansyaster

Psilactis heterocarpa is known from seven counties in the Gulf Coastal Plain of southern Texas.

Annuals, 25–100 cm. Stems and branches finely appressed-hairy, stipitate-glandular distally. Distal leaf blades sessile, lanceolate to linear-lanceolate, smallest 2–15 × 0.3–1.5 mm. Involucres broadly turbinate, 4–6 mm. Phyllaries lanceolate to linear, unequal, 2–4.5 × 0.5–0.7 mm, bases indurate, margins scarious. Receptacles flat to convex, 2–2.5 mm wide. Ray florets 15–25; laminae 4–5 × 0.7–1.3 mm. Disc florets 25–35; corollas 3–4 mm. Ray cypselae 1.3–1.5 mm, sparsely appressed-hairy. Disc cypselae 2–3 mm, glabrate or glabrous; pappi 25–40, 3.2–4 mm. 2n = 6.

Machaeranthera heterocarpa R. L. Hartman & M. A. Lane, Brittonia 39: 253, figs. 1, 2A, B, 3A. 1987