Sand dune chinchweed

Chthonia glaucescens Cassini in F. Cuvier, Dict. Sci. Nat. ed. 2, 9: 173. 1817; Pectis leptocephala (Cassini) Urban; P. lessingii Fernald

Annuals or perennials, 2–50 cm (across or high); herbage spicy-scented. Stems prostrate to erect, usually sparsely to densely puberulent (sometimes in decurrent lines), sometimes glabrate. Leaves narrowly linear, 10–35 × 0.2–1.8 mm, margins with 1–5 pairs of setae 1–2 mm, faces glabrous (abaxial submarginally dotted with broadly elliptic to circular oil-glands 0.2–0.3 mm, sometimes with additional, scattered oil-glands). Heads borne singly or in diffuse, cymiform arrays. Peduncles filiform, (3–)7–35(–54) mm. Involucres cylindric. Phyllaries distinct, linear-oblanceolate, 4–5 × 0.8–1 mm (dotted with 1–2 elliptic, subapical oil-glands 0.2–0.3 mm, sometimes with additional, smaller submarginal or scattered oil-glands). Ray florets 5; corollas 3.5–5 mm. Disc florets 3–7; corollas 2–3 mm (2-lipped). Cypselae 2.5–3 mm, strigillose; pappi of 0–5, antrorsely scabrid bristles or slender scales 1–2 mm plus 0–5 entire or irregularly lacerate scales 0.2–0.7 mm. 2n = 48.

Flowering year round. Sandy or gravelly soils, grassy areas, openings in pinelands, scrub, roadsides; 0–50 m; Fla.; West Indies (Bahamas, Hispaniola, Jamaica).

Pectis glaucescens is widespread in southern Florida and the Bahamas. Human disturbances, especially road constructions, have created habitats suitable for it. It grows most commonly on limestone soils in open, grassy sites. Occasionally, it is a lawn weed.