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Canada frostweed, Canada rockrose or frostweed, crocanthème du Canada

Habit Herbs.
Stems

ascending to erect, usually red-tinged, 15–50(–65) cm, stellate-pubescent to glabrate.

Leaves

cauline;

petiole 1–3 mm;

blade oblanceolate-elliptic to narrowly elliptic, tapered to base, 12–30(–38) × 4–7(–10) mm, apex acute, surfaces stellate-tomentose and with scattered simple hairs abaxially, ± lustrous, sparsely stellate-pubescent and with simple hairs adaxially, lateral veins raised abaxially.

Inflorescences

terminal or subterminal, cymes; chasmogamous flowers 1–3 per cyme, cleistogamous 1–3 per glomerule, on lateral leafy branches 6–18 cm, flowering 1–3 months later than chasmogamous.

Pedicels

(1.5–)4–10(–17) mm, with stellate and simple hairs;

bracts absent.

Chasmogamous

flowers: outer sepals narrowly lanceolate, 2–6 × 0.5–1 mm, inner sepals 5–9 × 3.5–5 mm, apex acute;

petals obovate, 8–15 × 6–14 mm;

capsules 5–8 × 4–7 mm, glabrous.

Cleistogamous

flowers: outer sepals rudimentary, 0.2–0.5 × 0.2–0.4 mm, inner sepals obovate, 2.5–4 × 2.5–3.5 mm, apex acute;

capsules 2.3–3.5 × 2.5–3.5 mm, glabrous.

2n

= 20.

Crocanthemum canadense

Phenology Flowering late Mar–Jul(–Aug).
Habitat Sandy or rocky barrens, glades, sandhills, prairies, fields, roadsides, maritime grasslands and heathlands, interdunes, pine-oak woodlands, oak-hickory woodlands, rocky slopes
Elevation 0–700 m (0–2300 ft)
Distribution
from FNA
AL; CT; DC; DE; GA; IA; IL; IN; KY; MA; MD; ME; MI; MN; MO; NC; NH; NJ; NY; OH; PA; RI; SC; TN; VA; VT; WI; WV; NS; ON; QC
[BONAP county map]
Discussion

Crocanthemum canadense and C. dumosum are distinguished from sympatric species by simple hairs among the stellate ones on leaf surfaces and by reddish colored stems. Until the twentieth century, C. canadense was treated much more broadly, to include C. bicknellii, C. dumosum, and C. propinquum; it differs from C. bicknellii and C. propinquum by having simple hairs on foliage (versus stellate only) and larger cleistogamous capsules. Its closest relative is 7. C. dumosum; see that treatment for identification aids.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Source FNA vol. 6, p. 403.
Parent taxa Cistaceae > Crocanthemum
Sibling taxa
C. aldersonii, C. arenicola, C. bicknellii, C. carolinianum, C. corymbosum, C. dumosum, C. georgianum, C. glomeratum, C. greenei, C. nashii, C. propinquum, C. rosmarinifolium, C. scoparium, C. suffrutescens
Synonyms Cistus canadensis, Helianthemum canadense, H. canadense var. sabulonum, Lechea major
Name authority (Linnaeus) Britton: in N. L. Britton and A. Brown, Ill. Fl. N. U.S. ed. 2, 2: 540. (1913)
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