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Cascade rock-cress, Cascade suncress, Cascades rockcress, littleleaf rockcress

Habit Perennials; long-lived; (cespitose); apomictic; caudex somewhat woody. Perennials; usually long-lived; apomictic; caudex often woody.
Stems

usually 1 per caudex branch, arising from center of rosette near ground surface, 0.5–2.2 dm, sparsely pubescent proximally, trichomes simple and short-stalked, 2- or 3-rayed, 0.1–0.2 mm, glabrous distally.

usually 1 per caudex branch, arising from center of rosette near ground surface, 1.5–4.5 dm, densely pubescent proximally, trichomes short-stalked, 4–9-rayed, 0.05–0.2 mm, glabrous or sparsely pubescent distally.

Basal leaves

blade linear-oblanceolate, 0.7–2 mm wide, margins entire, ciliate proximally, trichomes to 0.4 mm, surfaces densely pubescent, trichomes short-stalked, (2- or) 3–6-rayed, 0.05–0.2(–0.3) mm.

blade linear to narrowly oblanceolate, 1–4 mm wide, margins entire, ciliate at petiole base, trichomes (simple), to 0.5 mm, surfaces densely pubescent, trichomes short-stalked, 4–9-rayed, 0.05–0.2 mm.

Cauline leaves

4–6, not concealing stem;

blade auricles 0.5–1 mm, surfaces of distalmost leaves glabrous.

5–9, not concealing stem;

blade auricles 0.5–1 mm, surfaces of distalmost leaves sparsely pubescent.

Racemes

3–11-flowered, unbranched.

10–18-flowered, sparingly branched.

Flowers

ascending at anthesis;

sepals glabrous or sparsely pubescent;

petals lavender, 5–6 × 1–1.7 mm, glabrous;

pollen spheroid.

divaricate-ascending at anthesis;

sepals pubescent;

petals lavender, 5–7 × 0.7–1.2 mm, glabrous;

pollen spheroid.

Fruiting pedicels

ascending to divaricate-ascending, straight, 3–8 mm, glabrous.

divaricate-descending, gently curved downward, 6–12 mm, pubescent, trichomes appressed, branched.

Fruits

ascending to divaricate-ascending, not appressed to rachis, not secund, straight, edges parallel, 3.5–6.2 cm × 1.2–1.5 mm;

valves glabrous;

ovules 58–80 per ovary;

style 0.8–1.5 mm.

divaricate-descending, not appressed to rachis, not secund, gently curved, edges parallel, 4.5–6 cm × 1.2–1.5 mm;

valves glabrous;

ovules 62–80 per ovary;

style 0.5–1 mm.

Seeds

uniseriate, 1.1–1.3 × 0.9–1 mm;

wing continuous, 0.05–0.1 mm wide.

uniseriate, 1.2–1.7 × 0.8–1.2 mm;

wing mostly distal, 0.05–0.1 mm wide.

Boechera cascadensis

Boechera falcifructa

Phenology Flowering Jun. Flowering May–Jun.
Habitat Basaltic cliffs and rocky slopes in subalpine areas Rocky slopes and sandy soil in sagebrush or pinyon-juniper woodlands
Elevation ca. 1900 m (ca. 6200 ft) 1500-1800 m (4900-5900 ft)
Distribution
from FNA
OR; WA
[BONAP county map]
from FNA
NV
[BONAP county map]
Discussion

Of conservation concern.

Morphological evidence suggests that Boechera cascadensis is an apomictic species that arose through hybridization between B. microphylla and B. paupercula (see M. D. Windham and I. A. Al-Shehbaz 2007 for detailed comparison). It is known from two collections: the type specimens from Kittitas County, Washington, and a more recent collection from Baker County, Oregon.

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

Of conservation concern.

Morphological evidence suggests that Boechera falcifructa is an apomictic species that arose through hybridization between B. cobrensis and B. fernaldiana. It is more similar to the former, but is distinguished by its gently curved fruiting pedicels (versus strongly recurved or reflexed distally), narrower (1.2–1.5 versus 1.7–2.5 mm) fruits, more (62–80 versus 34–64) ovules per ovary, longer (0.5–1 versus 0.05–0.2 mm) styles, and narrower (0.05–0.1 versus 0.25–0.5 mm) seed wings. Although independently reproducing, B. falcifructa is known only from Elko and Lander counties, where the parental species grow in proximity.

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

Source FNA vol. 7, p. 369. FNA vol. 7, p. 377.
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. 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. 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
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. 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. 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 microphylla var. thompsonii Arabis falcifructa
Name authority Windham & Al-Shehbaz: Harvard Pap. Bot. 11: 260. (2007) (Rollins) Al-Shehbaz: Novon 13: 385. (2003)
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