Boechera canadensis |
Boechera horizontalis |
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sicklepod, sicklepod rockcress |
Crater Lake rock-cress |
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Habit | Biennials; short-lived; sexual; caudex not evident. | Perennials; long-lived; (cespitose); apomictic; caudex woody. |
Stems | 1 per plant, arising from center of rosette near ground surface, 2.5–10(–12.5) dm, sparsely to densely pubescent proximally, trichomes simple, to 1 mm, glabrous or sparsely pubescent distally. |
usually 1 per caudex branch, arising from center of rosette, near ground surface or somewhat elevated on woody base, or 1–3.5 dm, sparsely pubescent proximally, trichomes short-stalked, 3–6-rayed, 0.1–0.3 mm, glabrous distally. |
Basal leaves | blade obovate to oblanceolate, 10–30 mm wide, margins dentate, ciliate proximally, trichomes simple, to 1 mm, surfaces moderately pubescent, trichomes simple, 0.5–1.5 mm, these mixed with smaller, 2- or 3-rayed ones. |
blade narrowly oblanceolate, 1–5 mm wide, margins entire, ciliate near petiole base, trichomes (simple), to 0.4 mm, surfaces densely pubescent, trichomes short-stalked, 3–6-rayed, 0.1–0.3 mm. |
Cauline leaves | 12–20, often concealing stem proximally; blade auricles absent or proximalmost blades with auricles 0.5–2(–5) mm, surfaces of distalmost leaves sparsely pubescent. |
3–13, often concealing stem proximally; blade auricles 0.5–1.5 mm, surfaces of distalmost leaves glabrous. |
Racemes | 15–65(–82)-flowered, sometimes branched. |
5–32-flowered, usually unbranched. |
Flowers | divaricate-ascending to horizontal at anthesis; sepals pubescent; petals white, 3–5 × 0.7–1.2 mm, glabrous; pollen ellipsoid. |
divaricate-ascending at anthesis; sepals pubescent; petals lavender to purple, 5–6 × 1.5–2 mm, glabrous; pollen spheroid. |
Fruiting pedicels | descending to horizontal, usually curved, rarely straight, 6–13(–17) mm, pubescent or glabrous, trichomes subappressed, usually 2-rayed. |
horizontal to descending, straight or slightly curved downward, 4–11 mm, glabrous. |
Fruits | pendent to horizontal, not appressed to rachis, often secund, curved, edges parallel, 4–10 cm × 2.5–4 mm; valves glabrous; ovules 40–62 per ovary; style 0.3–0.8(–1.1) mm. |
horizontal or descending, not appressed to rachis, secund, straight, edges slightly undulate (not parallel), 2–4 cm × 2–3 mm; valves glabrous; ovules 40–54 per ovary; style 0.2–0.5 mm. |
Seeds | uniseriate, 1.7–3.5 × 1.5–2.2 mm; wing continuous, 0.4–1 mm wide distally. |
uniseriate, 2–2.5 × 1.7–2 mm; wing continuous, 0.5–1 mm wide. |
2n | = 14. |
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Boechera canadensis |
Boechera horizontalis |
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Phenology | Flowering Apr–Jul. | Flowering Jul–Aug. |
Habitat | Bluffs, rocky slopes, ravines, open woods | Dry pumice slopes |
Elevation | 0-1200 m (0-3900 ft) | |
Distribution |
AL; AR; CT; DC; FL; GA; IA; IL; KS; KY; MA; MD; ME; MI; MN; MO; MS; NC; NE; NY; OH; OK; PA; TN; TX; VA; VT; WI; WV; QC
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OR |
Discussion | Morphological evidence suggests that Boechera horizontalis is an apomictic species that arose through hybridization between B. lemmonii and B. suffrutescens (M. D. Windham and I. A. Al-Shehbaz 2007). Boechera horizontalis is known only from the vicinity of Crater Lake in south-central Oregon. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Source | FNA vol. 7, p. 369. | FNA vol. 7, p. 384. |
Parent taxa | ||
Sibling taxa | ||
Synonyms | Arabis canadensis, Arabis falcata, Arabis hirsuta var. ovata, Arabis ovata | Arabis horizontalis, Arabis suffrutescens var. horizontalis |
Name authority | (Linnaeus) Al-Shehbaz: Novon 13: 384. (2003) | (Greene) Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 266. (2007) |
Web links |
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