World Botanical Associates Web Page
Prepared by Richard W. Spjut
Boechera. Perennials with erect simple stems, or often subshrubs with a short branched woody base and basal tufts (rosettes) of leaves (during growing season); leaves on flowering stems reduced, alternate, often narrower and shorter than basal leaves, not stalked (without petiole or sessile); flowers pedicelled, appearing shortly clustered near stem apex, white, lavender, or purple entirely or white and purple to lavender; fruits mature as stems elongate and develop more flowers, in linear arrays (racemes), on straight to curved pedicels, appearing linear to sickle-shaped, usually >10× longer than wide, flattened with the partition, seeds many in 1 or 2 rows. >100 spp., temperate E Asia and North America. Formerly in Arabis from which it is distinguished by branching of hairs, antler-like (“forked in Boechera”), star-shaped (“stellate”) in Arabis. 15 species in Kern County, 9 woody, 6 herbaceous [B. inyoensis (Summit of Mt. Jenkins, 2378 m), B. repanda (Greenhorn Mts. Kern Plateau, Tehachapi Peak.), B. retrofracta (Sierra Nevada east of Troy Meadow in lodgepole pine forest, 7700 ft), B. sparsiflora (Kern River Canyon, 914 m and Bodfish), B. stricta (northwest face of Spanish Needle, 2346 m)]. Most species of Boechera in Kern County occur in the Eastern Sierra Nevada, especially around Spanish Needle Peak.
Key to Subshrub Species of Boechera in Kern County
—Fruits ascending to erect above stem apex, not
—Leaves hairless; petals 6–10 mm; Tulare Co. line, Spanish Needle,
—Fruits all spreading in the same direction—off to one side of
—Fruits strongly arched 180–360º, ascending partly above the horizontal
—Flower stems to 45 cm high; basal leaves mostly entire, densely white
—Flowers/fruits 8–25 to a stem; seeds in 2 rows; Tehachapi Mts.,
Boechera arcuata (Streptanthus arcuatus Nuttall in Torrey & Gray 1838) Windham & Al-Shehbaz 2006 [Arabis sparsifolia Nuttall 1838 var. arcuata (Nuttall) Rollins 1936]. Pointed rockcress. Flower stems many from a branched woody base with loose rosettes of narrowly elliptic or canoe shaped leaves similar in shape to Atriplex canescens, or leaves slightly wider above middle, flower stems, one to a leaf rosette, to 80 cm high; basal leaves spreading to ascending to erect, keeled, tapered to base and to pointed apex, 2.5–6 cm long, 2–12 mm wide, densely hairy; stem leaves slightly reduced and slightly overlapping, erect (adpressed to stem), straight or bending away from stems above mid region of the blade, widest near base with basal lobe (auricle) on each side of midrib, sword-shaped and slightly twisted, gradually tapering or drawn-out to apex. Flowers Mar–Jun, white to lavender, ~10 in flower while others may have gone into fruit on lower part of stems, petals 9–14 mm; fruits on spreading to recurved pedicels 8–22 mm long, curved more above the mid region in an arc from 120º to nearly a complete circle (360º), decending or deflexed well below the horizontal plane ( 90º) from where attached to stem, hairy. Seeds in 1 row. Rocky ridges, cliffs, and slopes in pine forests and chaparral, mostly Sierra Nevada and Transverse Ranges in California with scattered occurrences in Central Coast Range and southern Warner Mts (CalFlora), 300–2000 m (JM2). Type from: “Shelving rocks, on high hills near St. Barbara, Upper California.—Stems growing in dense tufts, very rarely branched, 1–2 feet high. Calyx purplish. Petals deep reddish-purple.” Kern Co.: “Occasional in rocky places in the Douglas oak woodland in the Kern Canyon region” (Twisselamnn with further reference to synonym “A. hoboelii var. arcuata”); >30 CCH collections, largely from the Kern Canyon region, others from Breckenridge Mountain, Caliente Range, Erskine Creek, Fay Ranch, Spanish Needle Road, and Tehachapi Pass, mostly below 1400 m.
Boechera breweri (Arabis breweri S. Watson 1876) Al-Shehbaz 2003 ssp. breweri. Brewer’s rockcress. Flower stems many from a compact branched woody base with dense rosettes of elliptic to sppon-shaped leaves, reminiscent of some Dudleya species, flower stems to 45 cm high; basal leaves spreading to erect, concave on upper surface, shortly tapered to base and apex, 0.6–2 cm long, 3–11 mm wide, densely white hairy; stem leaves fewer, erect but not adpressed to stem, slightly reduced, overlapping along stems, widest near base extending into a basal lobe on each side of midrib, elliptical to broadly sword-shaped, spreading, tapering to a pointed apex. Flowers Mar–Jul, purple to lavender, 5–7 near apex, continuing to flower as stems elongate and fruit matures on lower stem, spreading 45–60º on pedicels 3–25 mm long, petals 7–12 mm; fruit arcuate 0–60 (-180º), curving more near mid region to near base, the tip reaching near or just below horizontal axis from where pedicel is attached to stem, 3.5–7.5 cm in length, mostly hairless. Seeds in 1 row. Rock ledges and talus slopes near summits of mountain peaks in California and Oregon, in California mostly Klamath Mountains extending southwards to northern Sierra Nevada with isolated occurrences further south and in the Coast Ranges south to Monterrey County with isolated occurrence in Ventura County (CalFlora), 500–2300 m (FNA). Type from Mt. Diablo, California; holotype image at CalPhotos http://calphotos.berkeley.edu/cgi/img_query?stat=BROWSE_IMG&where-genre=Plant&where-taxon=Arabis+breweri&title_tag=Arabis+breweri. Kern Co. Rare, 2 collections; Southern Sierra Nevada along the northwest face of Spanish Needle Peak in rocky granitic areas, 2346 m (7700 ft), “uncommon” in association “with Penstemon newberryi, Cercocarpus intricatus, Dudleya calcicola, Allium shevockii, Eriogonum breedlovei var. shevockii, Heuchera and Eriophyllum confertiflorum” (Shevock & Larry Norris 11666, 10 June 1986, CCH-CAS); also “above Kern River, twenty miles east of Bakersfield on Walker Pass road;” “associated with Selaginella, Melica on steep rock[y] slopes” (A. A. Beetle, D. B. Beetle & Howard Schoof 2653, 10 Apr 1941, CCH-SEINET).
Boechera californica (Arabis sparsiflora Nuttall 1838 var. californica Rollins 1941) Al-Shehbaz 2007. California rockcress. Flower stems appearing few from an elevated woody base (FNA, JM2) but type not apparently woody (http://www.tropicos.org/Name/50295362) with relatively few rosette(s) of narrow elliptic leaves (or leaves widest above middle), to 130 cm high; basal leaves spreading, slightly twisted, long tapered to base and apex, 3–7× longer than wide, 3–10 mm wide, densely white hairy; stem leaves fewer, slightly reduced, slightly overlapping along stems, widest near base with a basal lobe on each side of midrib, sword-shaped, spreading, tapering to a pointed apex. Flowers Mar–Jun, purple or rarely pink, spreading ~90º on pedicels 4–20 mm long, petals 9–14 mm; fruit horizontal to decending, arcuate to 180º, curving more near mid region, 6–12 cm long, with few or no hairs. Rocky slopes and gravelly soil, desert chaparral and oak woodlands, southern California, 300–2300 m (FNA). Seeds in 1 row. Type from dry hills near Campo, San Diego Co., California. Kern Co. Rare, 2 CCH collections, vicinity of Spanish Needle Peak and Sorrell peak, 2255–2346 m: (1) Piute Mountains, lower Esperanza Canyon at eastern base of Sorrell Peak and western edge of Kelso Valley, 1372–1463 m, alluvial flats and moderate to steep slopes, granitic substrate with large boulder outcrops, loose, decomposed granite soils, vegetation recently burned (2006 or 2007), formerly dominated by scrub of Artemisia tridentata, Chrysothamnus nauseosus, Yucca brevifolia on flats, drier slopes scrubby woodland of Pinus sabiniana, P. monophytlla, Quercus wislizenii, Q. chrysolepis, Fremontodendron californicum, etc. (Boyd & Arvizum 1 May 2008, RSA); (2) ~20 mi wnw Ridgecrest, Pacific Crest Trail, between Lamont Meadows and Owens Peak, metamorphic rock outcrops along trail on west side of Spanish Needle, 6500 ft (Errter, Shevock & Sholars 7017, 26 May 1987, UC, annotated by Windham & Al-Shehbaz 2006 ).
Boechera davidsonii (Arabis davidsonii Greene 1911) N. H. Holmgren 2005. Davidson’s rockcress. Flower stems many from a branched woody base with rosettes of narrow spoon shaped leaves, each rosette with one flower stem, to 23 cm high; basal leaves numerous, crowded, basal part persistent, ascending to erect, 3–7 (-8) cm long, 3.5–14 mm wide, hairless; stem leaves fewer (3–7), much reduced, not overlapping, erect to bending away from stem above middle, widest below mid region, especially near base, tapered to a rounded apex. Flowers Apr–Jul, white to lavender, 4–24 on ascending to straight pedicels 3–18 mm; fruits straight in line with the pedicels or slightly curved upwards, ~45 º from stems, hairless. Seeds in 1 row. Rock outcrops at scattered locations; Santa Rosa Range in Nevada, Blue Mts. in Oregon, Warner Mts. and Sierra Nevada in California south to the Kern County line, 1200–3500 m. Type from moist rocks below Sabrina Lake, North Fork Bishop Creek, Inyo Co, California. Kern Co.: Rare, 3 CCH-CAS specimens from the vicinity of Spanish Needle Peak in Southern Sierra Nevada: Eastern crest, along the northwest face of Spanish Needle Peak in rocky granitic areas, 2346 m (7700 ft), “uncommon” in association “with Cercocarpus intricatus, Dudleya calcicola, Eriogonum breedlovei var. shevockii,” and “Heuchera” (Shevock & Larry Norris 11637, 11662, 10 June 1986); Kern Plateau, BLM-Owens Peak Wilderness, granitic talus outcrops on western slopes above the Pacific Crest Trail in open Jeffrey pine-white fir forest, northeastern side of Spanish Needle , 7400 ft (2255 m), ~2.5 miles southeast of Lamont Meadow (Shevock 11212, 15 June 1985).
Boechera lemmonii (Arabis lemmonii S. Watson 1887) W. A. Weber 1982. Lemmon’s rockcress. Flower stems many from a branched woody base partly creeping along ground with clustered narrow spoon shaped leaves, ascending to 40 cm high; basal leaves numerous, crowded on short shoots, the terminal portion appearing more rosette like, spreading, 0.7–2.5 cm long, 1.5–3.5 (-5) mm wide, hairy, at least on lower surface, sometimes hairless above; stem leaves fewer (2–12), much reduced, overlapping, erect but angled off to one side of the stem, not tapered to lobed (auricled) base, rounded to apex. Flowers Jun–Aug, purple to lavender, 3–17 on straight spreading to recurved pedicels 2–6 mm oriented along one side of the stem, petals 4–6 mm; fruits ascending to spreading nearly at right angles, straight in line with the pedicels or slightly curved downwards up to ~30 º arc (fruits in preceding species spread spirally not along one side of the stem), 1.6–4.4. cm long, hairless. Seeds in 1 row. Subalpine and alpine talus, 2300–3950 m; Alaska south to Rocky Mountains, Colorado, and south into the Pacific Northwest and Sierra Nevada (mostly eastern portion) to the Kern County line, summit of Owens Peak. Type from Lassen Peak, California, 11,000 ft. Kern Co.: Rare, 1 CCH specimen: Occasional along the crest of the southern Sierra Nevada near the summit of Owens Peak, 8450 ft, in rocky metamorphic areas with open mixed coniferous forest of western juniper, limber pine and Jeffrey pine, associated with Salvia pachyphylla, Penstemon newberryi, Heuchera, Monardella, Leptodactylon, and Eriogonum spp. *Shevock, 27 May 1985, CAS).
Boechera perennans (Arabis perennans S. Watson 1887) W. A. Weber 1982. Rabbit-ear rockcress. Flower stems 2–5 (-6) from a branched woody base with clustered narrow spoon shaped leaves, ascending to 70 cm high; basal leaves numerous, crowded on short shoots, or rosette like, mostly erect, 1.0–3.0 cm long, 3.0–20 mm wide, tapered to base, rounded to apex, rounded to apex, often irregularly dentate to wavy along margins, hairy, at least on lower surface, sometimes hairless above; stem leaves fewer (2–12), much reduced, slightly overlapping, erect but not oblique to stem (off to one side of the stem), not tapered to lobed (auricled) base. Flowers Feb–May, white to purplish, 16–35 on straight wide spreading to slightly recurved pedicels (6-) 10–25 mm, oriented around the stem, petals 5–9 mm; fruits on horizontal to deflexed pedicels, straight in line with the pedicels, or slightly curved downwards in an arc up to ~180 º, hairless. Rocky and gravelly slopes and plains in desert regions, 1000–7000 ft, Rocky Mountains to California, south into Baja California. Kern Co.: Rare: 3 CCH collections: ~20 mi wnw Ridgecrest, Pacific Crest Trail, between Lamont Meadows and Owens Peak, metamorphic rock outcrops along trail on west side of Spanish Needle, 6500 ft (Errter, Shevock & Sholars 7021, 26 May 1987, UC, annotated by Windham & Al-Shehbaz 2006).
Boechera platysperma (Arabis platysperma A. Gray 1865) Al Shehbaz 2003. Flatseed rockcress. Flower stems from a woody branched base, with clusters of narrow elliptic to nearly spoon shaped leaves, to 35 cm high; basal leaves numerous, spreading, 1.2–3.0 cm long, 3.0–10 mm wide, long tapered to base, shortly tapered to slightly pointed apex, hairy or not; stem leaves few, much reduced, not overlapping, erect to one side of the stem, not tapered to base, which is mostly not lobed (auricled), rounded to bluntly pointed apex. Flowers Jun–Aug, white to purplish, 2–7 on straight spreading pedicels 3–10 mm, oriented around the stem, petals 4–6 mm; fruit spreading on pedicels ~45º from stem, straight in line with the pedicels or slightly curved upwards—not more than 30 º arc—to above stem apex, hairless. Seeds in 1 row. Rocky flats and slopes in lodgepole and ponderosa pine forests and montane chaparral, 1800–3000 ft; Oregon, Nevada, and California, south to San Gabriel Mts.. Kern Co.: “A typical plant of the Sierra Nevada that reaches the southern limits on the north slopes of Sunday Peak and along the ridge southeast of Pine Flat on the Kern Plateau” (Twisselmann), 2179–2301 m (CCH, 4 specimens all collected by Twisselmann).
Boechera pulchra (Arabis pulchra M. E. Jones ex S. Watson 1887) 1982. Desert rockcress. Flower stems 2–5 (-6) from center of an elevated woody base from a stout woody taproot, densely clustered with nearly linear or rolled inward leaves as in Atriplex canescens, to 75 cm high; basal leaves numerous, crowded near base, erect to spreading, 2.4–5.5 (-7.5) cm long, 1.0–3.0 mm wide, long tapered to base, very shortly tapered to slightly pointed apex, hairy; stem leaves numerous, similar but shorter than basal leaves, closely overlapping, erect to spreading or recurved, distributed around the stems, truncated to stems without lobes or at most 0.4 mm. Flowers Mar–Jun, purple, on straight spreading pedicels 5–14 mm, appearing mostly near stem apex but as many as 25 flowers develop as stem elongates and fruits develops below on wide spreading pedicels, petals 8–18 mm; fruits mostly straight, sharply deflexed at junction with pedicels, occasionally oriented to one side of the stem, the pedicels spreading at nearly right angles to the stems, hairy throughout. Seeds in 2 rows. Rocky and gravelly flats and slopes in blackbrush and sagebrush scrub, chaparral, and in pinyon-juniper woodlands, 600–2800 m; Rocky Mountains, southern Wyoming to Oregon, south to Baja California and northern Arizona. Type from near Carson City, Nevada. Kern Co.: “Occasional in the pinyon-juniper woodland and the arid shrub association on the east slope of the mountains southwest to Ballinger Canyon in the upper Cuyama Valley, often growing through low shrubs on arid slopes” (Twisselmann), 883–2195 m (CCH, most specimens 1200–1500 m. not reported from Cuyama Valley).
Boechera xylopoda Windham & Al-Shehbaz 2007 (substitute name for Arabis pulchra var. gracilis M. E. Jones 1898). Bigfoot hybrid rockcress. Flower stems 2–5 (-6) from center of an elevated woody base from a stout woody taproot, densely clustered with narrowly elliptic leaves, to 75 cm high; basal leaves numerous, crowded near base, erect to spreading, 3–7× longer than wide , 3–7.m wide, long tapered to base, very shortly tapered to slightly pointed apex, hairy; stem leaves numerous, similar but shorter than basal leaves, closely overlapping, erect to spreading or recurved, distributed around the stems, truncated at base with lobes 1–2 mm. Flowers Mar–May, purple, on straight spreading pedicels 5–14 mm, appearing mostly near stem apex but as many as 25 flowers develop as stem elongates and fruits develop below, petals 9–12 mm; fruits mostly on wide spreading pedicels—at right angles to stems, sharply deflexed at junction with pedicels, relatively straight, hairy in upper two-thirds. Seeds in 2 rows. Generally growing under shrubs of rocky and gravelly slopes in high desert communities, 800–2500 m; California, Nevada and southern Utah. Type from Inyo Co., Argus Mts., “Shepherd’s Canyon, 4,600 ft. Kern Co.: Eastern Sierra Nevada and Kern Plateau, 1159–2287 m [CCH—Head of Spanish Needle Creek 4659–4800 ft (Twisselmann 3 Jun 1965, Howell & True 13 May 1969); on trail to Owen’s Peak, 1890 m, associated with Pinus sabiniana, Pinus monophylla, Quercus chrysolepis, and Bromus tectorum (Fraga & Griffith 1 May 2004); along dry stream, scree shoot of very steep slope, 2287–2378 m (Fraga & Griffith 5 Jun 2003); open south facing talus slope of metamorphic rock between Morris Peak and Mt. Jenkins, associated with Pinus monophylla, Eriogonum umbellatum var. subaridum, Quercus chrysolepis, Artemisia tridentata, Monardella odoratissima, Gilia brecciarum ssp. neglecta (Fraga & Anderson 29 Apr 2004); east slope above Indian Wells Canyon, 1707 m, Grapevine Canyon, 1159 m (Fraga et al. 19 May 2003, 14 May 2004).