Plants 10–30 cm; proximal unbranched portions of primary stems usually longer than branches supporting heads. Leaves mostly on primary stems (distal leaves of primary stems not congested) and immediately proximal to branches supporting heads. Heads usually erect in bud and fruit. Phyllaries 3–6, hirsute and/or hirtellous near folded edges. Ray florets 3–6; corolla laminae 4–5 mm. Disc florets 8–13, some or all bisexual, fertile. Ray cypselae not gibbous, beakless; pappi to 0.5 mm. Disc cypselae 3–3.5 mm; pappi of 9–11 lanceolate to linear, fimbriate scales 0.6–0.8 mm. 2n = 18.

Flowering Apr–May. Serpentine slopes; of conservation concern; 100–200 m; Calif.

Harmonia guggolziorum occurs in the southern Inner North Coast Ranges. Molecular phylogenetic analyses have indicated a sister-group relationship between H. guggolziorum and the other serpentine-endemic species of Harmonia (H. doris-nilesiae, H. hallii, and H. stebbinsii; B. G. Baldwin 2001).