Boechera suffrutescens (S. Watson) Dorn, Brittonia 55: 3. 2003

Morin, David P., Alexander, Patrick J., Beck, James B., Windham, Michael D. & Bailey, C. Donovan, 2018, Deciphering the sexual diploid members of the Boechera suffrutescens complex (Brassicaceae, Boechereae), PhytoKeys 98, pp. 15-50 : 32-33

Boechera suffrutescens (S. Watson) Dorn, Brittonia 55: 3. 2003 Figures 3 , 9

Type.

U.S.A. Oregon. Wallowa County / Baker County: Bluffs of Snake River and vicinity, 1881, W.C. Cusick 919 (holotype: GH!; isotype: ORE) .

GH holotype image - http://kiki.huh.harvard.edu/databases/specimen_search.php?mode=details&id=27057

Description.

Plants long-lived perennials, with woody caudices raised above ground level 1-5 cm, lacking crowded, persistent leaf bases; herbage without an obvious bluish cast. Fertile stems usually 1 per caudex branch, arising centrally from basal rosettes, lower parts glabrous or glabrate with 1-2(3) rayed trichomes (0.1-0.3 mm). Leaves at stem bases narrowly oblanceolate to obsubulate, 1.5-6.0 mm wide, entire, not ciliate or rarely with simple trichomes to 0.7 mm, blade surfaces usually glabrous or sparsely pubescent with 1-3(4) rayed trichomes, but occasionally plant herbage basally pubescent with short-stalked 1-4(5)-rayed trichomes (0.07-0.40 mm) if stressed or sterile; cauline leaves (4-)6-12, sometimes concealing stem proximally, the uppermost glabrous, with auricles 0.8-4.5 mm long. Inflorescences mostly unbranched, 6-12-flowered; fruiting pedicels 4-18 mm, reflexed, usually distinctly geniculate proximally but otherwise straight, glabrous. Flowers pendent at anthesis; sepals glabrous; petals purple or whitish with rose tips, 4.5-6.0 mm long × 2.0-2.5 mm wide, glabrous; anthers with mostly well formed, narrowly ellipsoid, symmetrically tricolpate pollen; ovules 20-30 per fruit. Fruits 1.7-5.5 cm long × 3.3-4.0 mm wide, reflexed, pendent, occasionally appressed to rachises, often secund, straight to somewhat curved, with undulate edges, glabrous; apical angle of fruit valve 15°-23° (measured from base of style to 5 mm proximate); style persistent, 0.4-1.2 mm in length. Seeds uniseriate, 2.5-5.5 × 1.8-3.5 mm; wing continuous, 0.8-1.5 mm wide.

Distribution, habit and phenology.

Boechera suffrutescens is distributed north and east of the Great Basin; concentrated in the vicinity of the Snake River Gorge (Hells Canyon), but extending from Grant County, Oregon to central Idaho on steep, rocky, basaltic substrates in alpine and subalpine ecozones at elevations from 1800-2500 m; flowering from May-July.

Comments.

Although geographically isolated from the other S2X species of the complex, B. suffrutescens s.s. is the least distinct morphologically. The most useful character for distinguishing this species is that individuals usually have basal leaves that are glabrate, with a few 1(-2) rayed trichomes scantily dispersed along the margins and apices. However, plants are occasionally encountered that are pubescent basally with 1-3(-4) rayed trichomes. These individuals often appear stressed or lack flowering stems, suggesting that pubescence may be more prevalent amongst plants growing in unfavourable environments. On the holotype specimen, one of each morphotype is present and the plant lacking a flowering stem is pubescent. All other taxa in the complex are consistently pubescent basally. On robust individuals of B. suffrutescens s.s., the basal leaves are generally narrower and the fruits are generally wider than those of the other S2X taxa.

Specimens examined.

Idaho. Adams County: Confluence of Wildhorse River and No Business Cr. On N & W exposures, 13 May 1987, D. Atwood 12561 (GH). Valley County : In basaltic outcrop on E side of high ridge W of Cascade. Payette NF, 15 Jul 1937, R.C. Rollins 13852 (UC). Wash County : Seven Devils Mts. , 10 Jul 1899, M.E. Jones 6164 A, B ( RSA). Washington County : Middle slopes of Hitt Mountain , 15 Jun 1943, C.H. Christ 14044 (OSC); Dry hillside above Spring Creek . Ida Range 5 W Twsp. 14 North, 22 Jun 1940, R.J Davis 2184 A, B, C (GH). Oregon. Grant County : West rim of High Lake Basin , Blue Mts. , 4 Aug 1946, B. Maguire 26497 (UC). Union (Baker / Wallowa) County: Bluffs of Snake River and vicinity, 1881, W.C. Cusick 919 (GH); Stony hills near Snake River , 26 May 1898, W.C. Cusick 1808 (UC); Overlooking Hells Canyon from west. Northeast of Hells Canyon Overlook. E +/- 100 yards from NFD 490. Take unpaved NFD 490 NE +/- 3mi from Wollawa Mountain Loop , 22 Jun 2012, D.P. Morin 10 A, B, C, D (NMC), E, F (DUKE); ESE facing slope 1/ 4 mi NE from dirt Hat Point Road on E side of Saddle Creek Campsite. Overlooks the Seven Devils Mtns and Saddle Creek to the east, a tributary to Snake River , 25 Jun 2012, D.P. Morin 11 A (NMC); Hat Point Road and Saddle Creek Campground. Overlooks the Seven Devils Mtns and Saddle Creek Canyon to the E., 26 Jun 2012, D.P. Morin 12 A, B, C (NMC); ENE facing rocky basalt on W side of Wallowa Mountain Loop. +/- 1.5 mi N of turnoff to Lick Creek Campground. 16.5 air miles SE of Joseph., 25 Jun 2012, D.P. Morin 14 A, B, C, D (NMC), E, F, G (DUKE); Snake River Canyon near the mouth of Battle Cr., 12 Jul 1933, M.E. Peck 17616 (OSC); SE of Enterprise near crest overlooking McGraw Creek E of Forest Route 490 ca. 0.25 road mi NE of the parking area at Hells Canyon Overlook, 22 Jun 2012, M.D. Windham 4110 (DUKE); SE of Enterprise on slope above Lick Creek along Wallowa Mountain Loop Rd. ca. 14.1 road mi W of its junction with Upper Imnaha Rd., 22 Jun 2012, M.D. Windham 4132 (DUKE) .

Figures

Figure 3. Geographic distribution of B. suffrutescens (CP-su, SNP-su, and TL-su) and B. rollei (TL-ro) lineages inferred from Analysis 2. A map of Plumas Co., California with distributions of the B. constancei clusters is presented in Fig. 4.

Figure 9. Boechera suffrutescens, Morin, Windham, Allphin 14 (NMC).