6. Crocanthemum corymbosum (Michaux) Britton in N. L. Britton and A. Brown, Ill. Fl. N. U.S., ed. 2. 2: 541. 1913.
Pine barren frostweed Pine barren frostweed
Helianthemum corymbosum Michaux, Fl. Bor.-Amer. 1: 307. 1803; Cistus corymbosus (Michaux) Poiret
Herbs or subshrubs. Stems ascending to erect, 10–30(–50) cm, stellate-pubescent, glabrescent. Leaves cauline; petiole 1–5 mm; blade <bicolor>, obovate-elliptic to elliptic-lanceolate, 12–35(–47) × 3–10(–13) mm, <base cuneate, apex obtuse>, surfaces stellate-pubescent, lateral veins raised abaxially. Inflorescences terminal, compound dichasia in corymbiform cymes; chasmogamous flowers 1–6 per dichasium, <overtopping cleistogamous>, cleistogamous 10–45 per dichasium, <produced simultaneously>. Pedicels 6–15 mm, <villous and stellate-pubescent>; bracts 2–7 × 0.2–1.2 mm. Chasmogamous flowers: outer sepals spatulate-linear, 2.4–4.5 × 0.7–1.2 mm, <apex obtuse>, inner sepals 3–7 × 2.5–3.6 mm, apex acute to acuminate; petals obovate, 6–11 × 5–9.5 mm; capsules 3.6–5.4 × 3–4 mm, glabrous. Cleistogamous flowers: outer sepals linear, 1.8–3 × 0.3–0.9 mm, inner sepals ovate, 2.2–4.8 × 1.2–3 mm, apex acute; capsules 1.6–3.8 × 1.4–3 mm, glabrous.
Flowering late Feb–Apr. Stable maritime dunes, maritime forests, sandy pinelands, live-oak woodlands; 0–50 m; Ala., Fla., Ga., Miss., N.C., S.C.
Crocanthemum corymbosum is unique in Crocanthemum because of its corymbose inflorescence of long-pedicelled petaliferous flowers overtopping subsessile, apetalous flowers. Other species may produce long-pedicelled petaliferous flowers; the inflorescence shape is different. The two flower types develop synchronously, unlike in other species except C. glomeratum. The bicolored leaves, dark adaxially and pale abaxially, are a strong field and herbarium character.