Crocanthemum rosmarinifolium
Crocanthemum dumosum
rosemary frostweed
bushy frostweed, bushy rockrose or frostweed
ascending to erect, (13–)20–40(–51) cm, stellate-tomentose.
ascending to divergent, usually red-tinged, 10–20(–30) cm, stellate-pubescent.
cauline and, sometimes, basal basal mat-forming;
petiole 1–3 mm;
blade obovate, 10–22 × 3–5 mm;
cauline: petiole 1–4 mm;
blade oblanceolate to narrowly lanceolate, 10–38(–48) × 2–5.5(–7.8) mm, margins revolute;
surfaces stellate-tomentose abaxially, stellate-pubescent adaxially, without simple hairs;
lateral veins obscure abaxially.
cauline;
petiole 1–2 mm;
blade usually elliptic, rarely oblanceolate, 10–20(–26) × 3–7(–10) mm, tapered to base, apex acute, surfaces stellate-tomentose and with simple hairs abaxially, dull, stellate-pubescent and with simple and, sometimes, glandular hairs adaxially, lateral veins raised abaxially.
axillary and terminal, solitary flowers or glomerules; chasmogamous flowers solitary, at tips of branches, overtopping cleistogamous, cleistogamous 2–7 per glomerule, flowering 1–3 months later than chasmogamous.
terminal or subterminal, cymes; chasmogamous flowers 1–3 per cyme, cleistogamous 1(–2) per glomerule, on lateral leafy branches 6–18 cm, flowering 1–3 months later than chasmogamous.
10–22 mm;
bracts 3–7 × 0.5–1 mm.
2.4–6 mm, with stellate, simple, and glandular hairs;
bracts absent.
flowers: outer sepals linear, 1.2–2.5 × 0.2 mm, inner sepals 2.5–4.3 × 1.3–2 mm, apex acute;
petals obovate, 4–6 × 3.5–5 mm;
capsules 2–3 × 1.4–1.8 mm, glabrous.
flowers: outer sepals lanceolate, 2–6 × 0.8–3 mm, inner sepals 7–10 × 4—-6.5 mm, apex acute;
petals obovate, 8–15 × 5–13 mm;
capsules 4–7 × 3–4 mm, glabrous.
flowers: outer sepals linear, 0.5–1 × 0.2 mm, inner sepals ovate, 1.5–1.8 × 1–1.5 mm, apex acute;
capsules 1.3–1.7 × 1–1.3 mm, glabrous.
flowers: outer sepals rudimentary, knoblike to triangular and acute, 0.4–1 × 0.3–0.6 mm, inner sepals ovate, 3–6 × 2.5–3.2 mm, apex acute;
capsules 3.2–4.5 × 2.5–3.2 mm, glabrous.
Crocanthemum rosmarinifolium
Crocanthemum dumosum
Crocanthemum rosmarinifolium is easily distinguished from sympatric species by its slender leaves, relatively small petaliferous flowers, occasional basal leaves, and overall pale color. As noted by R. M. Harper over a century ago, it seems not to occupy natural habitats and is found primarily on roadsides. Populations in the Dominican Republic occur up to at least 2200 m.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Crocanthemum dumosum occurs in nine coastal counties. Crocanthemum dumosum and C. canadense are closely related; the former inhabits specialized, maritime environments. They can be distinguished in the field by the ascending or divaricate, relatively numerous stems of C. dumosum, often giving it a bushy aspect (versus erect, single or relatively few stems, and nonbushy); leaf surfaces dull under dense stellate hairs in C. dumosum (versus lustrous under sparser stellate hairs). Identification of occasional plants may be equivocal; those are a small minority.
Using AFLP markers, S. G. Obae et al. (2013) found that Crocanthemum dumosum nested within the same cluster as C. canadense. The authors “recommend that it be considered as a subspecific variant of C. canadense,” but did not make a new combination. Additional molecular work warranted to solidify their findings.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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