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Rolle's rock-cress

Habit Perennials; long-lived; sexual; caudex woody. Perennials; short- to long-lived; (cespitose); sexual; caudex usually not woody.
Stems

usually 1 per caudex branch, arising from center of rosette, elevated above ground surface on woody base, 1.5–2.5 dm, glabrous throughout.

usually 3–7 per caudex branch, arising from margin of rosette near ground surface, or arising laterally proximal to sterile shoots, 0.4–2.5 dm, glabrous or pubescent proximally, trichomes simple and short-stalked, 2-rayed, 0.1–0.4 mm, glabrous distally.

Basal leaves

blade oblanceolate, 3–8 mm wide, margins entire, ciliate proximally, trichomes (simple), 0.2–0.7 mm, surfaces glabrous or sparsely pubescent, trichomes short-stalked, 2–4-rayed, 0.2–0.4 mm.

blade linear to linear-oblanceolate, 1–2.5 mm wide, margins usually entire, rarely denticulate, often ciliate, trichomes (simple), 0.3–0.7 mm, surfaces glabrous or sparsely pubescent, trichomes short-stalked, 2- or 3-rayed, 0.1–0.4 mm.

Cauline leaves

6–12, sometimes concealing stem proximally;

blade auricles 0.5–2.5 mm, surfaces of distalmost leaves glabrous.

3–12, not concealing stem;

blade auricles absent, surfaces of distalmost leaves usually glabrous, rarely sparsely pubescent.

Racemes

3–7-flowered, unbranched.

2–12-flowered, unbranched.

Flowers

divaricate-ascending at anthesis;

sepals glabrous;

petals creamy white, 8–11 × 2–2.5 mm, glabrous;

pollen ellipsoid.

ascending-divaricate at anthesis;

sepals glabrous or pubescent;

petals white to pale lavender, 4–5 × 1.5–2 mm, glabrous;

pollen ellipsoid.

Fruiting pedicels

strongly curved proximally, 4–6 mm, glabrous.

divaricate-ascending to horizontal, slightly to strongly recurved, 3–8 mm, glabrous or sparsely pubescent, trichomes (isolated), simple.

Fruits

pendent, not appressed to rachis, not secund, straight to slightly curved, edges undulate (not parallel), 3.5–6 cm × 2.5–3.5 mm;

valves glabrous;

ovules 14–22 per ovary;

style 0.5–1 mm.

pendent, not appressed to rachis, not or, rarely, weakly secund, straight, edges parallel, 1.5–3.5 cm × 1.2–2 mm;

valves glabrous;

ovules 28–44 per ovary;

style 0.1–0.4 mm.

Seeds

uniseriate, 3–4 × 1.5–2 mm;

wing distal and proximal, 0.3–0.6 mm wide.

uniseriate, 0.9–1.2 × 0.6–1 mm;

wing often continuous, 0.07–0.1 mm wide.

Boechera rollei

Boechera oxylobula

Phenology Flowering Aug. Flowering May–Jul.
Habitat Peridotite rocks on sparsely forested slopes Cliffs, rocky slopes, gravelly soil in sagebrush and open conifer forests
Elevation 1600-1800 m (5200-5900 ft) 2100-3600 m (6900-11800 ft)
Distribution
from FNA
CA
[BONAP county map]
from FNA
CO
[BONAP county map]
Discussion

Boechera rollei is easily distinguished from the habitally similar B. suffrutescens by its longer (8–11 versus 4.5–6 mm) petals, narrower (2.5–3.5 versus 3–6 mm) fruits, and narrower (0.3–0.6 versus 0.8–1.5 mm) seed wings. This distinctive sexual species is known only from the vicinity of the type locality on the divide between the Applegate and Klamath Rivers in Siskiyou County.

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

Most of the collections assigned here have been called Arabis (Boechera) demissa by other authors (e.g., R. C. Rollins 1993; N. H. Holmgren 2005b). Because the holotype of A. demissa is identical to B. oxylobula in nearly every way (see M. D. Windham and I. A. Al-Shehbaz 2006 for detailed comparison), we treat them as conspecific. Boechera oxylobula is restricted to Garfield, Gunnison, Hinsdale, Lake, Mineral, Park, and Saguache counties in central Colorado. The taxon traditionally treated as A. (Boechera) demissa var. languida is here recognized as an apomictic species of hybrid origin (see Windham and Al-Shehbaz 2007b for detailed comparison).

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

Source FNA vol. 7, p. 403. FNA vol. 7, p. 391.
Parent taxa Brassicaceae > tribe Boechereae > Boechera Brassicaceae > tribe Boechereae > Boechera
Sibling taxa
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. cobrensis, B. collinsii, B. consanguinea, B. constancei, B. covillei, B. crandallii, B. cusickii, B. davidsonii, B. dentata, B. depauperata, B. dispar, B. divaricarpa, B. drepanoloba, B. duchesnensis, B. elkoensis, B. evadens, B. falcatoria, B. falcifructa, B. fecunda, B. fendleri, B. fernaldiana, B. formosa, B. fructicosa, B. glareosa, B. glaucovalvula, B. goodrichii, B. gracilenta, B. gracilipes, B. grahamii, B. gunnisoniana, B. harrisonii, B. hastatula, B. hoffmannii, B. holboellii, B. horizontalis, B. howellii, B. inyoensis, B. johnstonii, B. koehleri, B. laevigata, B. languida, B. lasiocarpa, B. lemmonii, B. lignifera, B. lincolnensis, B. lyallii, B. macounii, B. microphylla, B. missouriensis, B. nevadensis, B. ophira, B. oxylobula, B. paddoensis, B. pallidifolia, B. parishii, B. pauciflora, B. paupercula, B. peirsonii, B. pendulina, B. pendulocarpa, B. perennans, B. perstellata, B. pinetorum, B. pinzliae, B. platysperma, B. polyantha, B. porphyrea, B. pratincola, B. puberula, B. pulchra, B. pusilla, B. pygmaea, B. quebecensis, B. rectissima, B. repanda, B. retrofracta, B. rigidissima, B. rollinsiorum, B. rubicundula, B. saximontana, B. schistacea, B. serotina, B. serpenticola, B. shevockii, B. shockleyi, B. sparsiflora, B. spatifolia, B. stricta, B. subpinnatifida, B. suffrutescens, B. texana, B. tiehmii, B. tularensis, B. ultra-alsa, B. villosa, B. williamsii, B. xylopoda, B. yorkii
B. acutina, B. arcuata, B. atrorubens, B. bodiensis, B. breweri, B. burkii, B. calderi, B. californica, B. canadensis, B. cascadensis, B. cobrensis, B. collinsii, B. consanguinea, B. constancei, B. covillei, B. crandallii, B. cusickii, B. davidsonii, B. dentata, B. depauperata, B. dispar, B. divaricarpa, B. drepanoloba, B. duchesnensis, B. elkoensis, B. evadens, B. falcatoria, B. falcifructa, B. fecunda, B. fendleri, B. fernaldiana, B. formosa, B. fructicosa, B. glareosa, B. glaucovalvula, B. goodrichii, B. gracilenta, B. gracilipes, B. grahamii, B. gunnisoniana, B. harrisonii, B. hastatula, B. hoffmannii, B. holboellii, B. horizontalis, B. howellii, B. inyoensis, B. johnstonii, B. koehleri, B. laevigata, B. languida, B. lasiocarpa, B. lemmonii, B. lignifera, B. lincolnensis, B. lyallii, B. macounii, B. microphylla, B. missouriensis, B. nevadensis, B. ophira, B. paddoensis, B. pallidifolia, B. parishii, B. pauciflora, B. paupercula, B. peirsonii, B. pendulina, B. pendulocarpa, B. perennans, B. perstellata, B. pinetorum, B. pinzliae, B. platysperma, B. polyantha, B. porphyrea, B. pratincola, B. puberula, B. pulchra, B. pusilla, B. pygmaea, B. quebecensis, B. rectissima, B. repanda, B. retrofracta, B. rigidissima, B. rollei, B. rollinsiorum, B. rubicundula, B. saximontana, B. schistacea, B. serotina, B. serpenticola, B. shevockii, B. shockleyi, B. sparsiflora, B. spatifolia, B. stricta, B. subpinnatifida, B. suffrutescens, B. texana, B. tiehmii, B. tularensis, B. ultra-alsa, B. villosa, B. williamsii, B. xylopoda, B. yorkii
Synonyms Arabis rollei Arabis oxylobula, Arabis aprica, Arabis demissa, Arabis rugocarpa, B. demissa
Name authority (Rollins) Al-Shehbaz: Novon 13: 389. (2003) (Greene) W. A. Weber: Phytologia 51: 370. (1982)
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