Boechera duriuscula (Greene) D.P. Morin, 2018

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 : 31

Boechera duriuscula (Greene) D.P. Morin comb. nov. Figures 3 , 7

Arabis duriuscula ≡ Arabis duriuscula Greene, Pittonia 4: 191. 1900. Type: U.S.A. California. Nevada County: Donner Lake, Michener s.n. (1893) and Sonne s.n. (1882). The repository of the Sonne syntype(s) is unknown at this time; the Michener syntype deposited at NDG has been included in our morphological and molecular analyses and is here designated as lectotype.

Description.

Plants long-lived perennials, with ± woody caudices occasionally raised above ground level, lacking crowded, persistent leaf bases; herbage without an obvious bluish cast. Fertile stems 1-3(-4) per caudex branch, each arising from a basal rosette; lower parts pubescent to densely pubescent with short-stalked, 2-3(4) rayed trichomes 0.1-0.3 mm. Leaves at stem bases oblanceolate, 1.7-5.8 mm wide, entire, ciliate with 2-3(-4) rayed trichomes to 0.07-0.40 mm; cauline leaves (4-)6-12, occasionally concealing stem proximally, the uppermost glabrous, with auricles (0)0.3-1.4 mm. Inflorescences mostly unbranched, 6-12 flowered; mature fruiting pedicels 9-17mm, reflexed, distinctly geniculate proximally, but otherwise straight, glabrous. Flowers pendent at anthesis; sepals glabrous; petals pale lavender or whitish with rose tips apically 4.5-6.0 mm long × 2.0-2.5mm wide; anthers with mostly well formed, narrowly ellipsoid, symmetrically tricolpate pollen; ovules 20-30 per fruit. Fruits 3-7(-10) cm long × 2.0-2.5 mm wide, pendent, straight to somewhat curved, with minutely undulate edges; apical angle of fruit valve <25° (measured from base of style to 5 mm proximate); style glabrous, 0.2-1.2 mm. Seeds uniseriate, 2.5-5.5 × 1.8-3.5 mm; wing continuous, 0.8-1.5 mm wide.

Distribution, habitat and phenology.

Boechera duriuscula is distributed in the Sierra Nevada from Kaiser Crest in Fresno County north to Mt. Hough in central Plumas County California. A few populations have been documented in Washoe, County Nevada, in the vicinity of Lake Tahoe. It is found on rocky or gravelly felsic substrates, often in association with Abies magnifica , Pinus jeffreyi and open Wyethia meadows at elevations from 2200-2750 m; flowering May-July.

Comments.

Boechera duriuscula is distinguished from B. suffrutescens s.s. by being persistently pubescent basally. It differs from B. botulifructa by having fruits that taper more gradually apically (<25° versus ≥30° as measured from the apex to a point 5 mm proximal to it).

Specimens examined. California.

Alpine County: Armstrong Pass , 9 miles south of South Tahoe , 12 Aug 1978, G.L. Stebbins 78149 A, C, D (CAS). El Dorado County : Summit area Echo Peak , 27 Jul 2012, G.L. Smith 2497 (JEPS); ENE of Kyburz below Cup Lake near head of Tamarack Creek ca. 1.17 km SSE of the summit (9235) of Ralston Peak. T 11N, R17E, Sec. 9. Lat.: 38°49'22"N Long.: 120°05'57"W (WGS84 Datum), 18 Jun 2002, M.D. Windham 2579 A (MO), A (NMC). Fresno County : Kaiser Crest, 27 Jul 1914, F.J. Smiy 621 (GH). Nevada County : Donner Lake , 1893, E. Michener s.n. (NDG); Truckee , Sierra Nevada Mountains , Jun 1892, C.F. Sonne 9 A, B, C (UC); Sierra Nevada. Just W of Truckee near Donner State Park ., 30 Jun 1965, G.H. True 2142 A, B (CAS). Placer County : NE from Highway 267, travel 3.4 mi on Martis Peak Road toward Martis Peak Lookout, 1 Jul 2012, D.P. Morin 32 A - E (NMC), F, G (DUKE), H, I, J (MO); Tahoe Nat'l Forest 3.5 air mi N of Lake Tahoe. 2.7 air mi NE of Brockway Summit. 3.7 road mi on Martis Peak Road from northern turnoff from Highway 267, 1 Jul 2012, D.P. Morin 34 A, B, C, (NMC); Tahoe Nat'l Forest . Turnout on N side of Road to Martis Peak Lookout. +/- 2.6 air mi from Brockway Summit., 1 Jul 2012, D.P. Morin 35 A, B, C, (NMC), D, E, F (DUKE), G, H, I (MO); Martis Peak, western flank near headwaters Monte Carlo Creek (T17N, R17E, S34, NE), 15 Jul 2005, D.W. Taylor 19408 (JEPS). Plumas County : North side of the summit of Mount Elwell , ± 0.1 miles N of the highest point, ± 1.8 miles SE of Mt. Washington, ± 14 miles NE of Downieville, northern Sierra Nevada , Plumas National Forest , 19 Apr 2009, P.J. Alexander 864 A, B (NMC); Sierra Nevada. Jamison Creek ., 27 Jun 1951, J.T. Howell 27628 A, B, C (CAS); Summit ridge of Mt. Hough , 11 Jul 1967, J.T. Howell 43348 A (GH), (CAS); Mount Hough Summit , ca. 7 mi NNE of Quincy., 5 Aug 1982, M.S. Taylor 4927 A, B, C (CAS). Sierra County : At Verdi Peak Lookout, Verdi Range., 14 Jul 1970, J.T. Howell 5522 A, C, D (CAS); Sierra Nevada. Near Mount Etna , 4 mi E of Gibsonville. Sierra-Plumas county line., 20 Jul 1975, A. Tiehm B (CAS). Tuolumne County : 2 mi w Sonora Pass, 27 Jul 2005, R.C. Rollins 2993 (UC), ( RSA). Nevada. Washoe County : Peavine Mountain , S of Murpheys meadow, T18N R20E sec. 17, 8 Aug 1974, A. Tiehm 505 (UNR); Sierra Nevadas, Carson Range, N side of Galena Creek on the south side of Mt. Rose, 5 Aug 1983, A. Tiehm 8279 B, C (CAS) .

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 7. Boechera duriuscula, Tiehm and Nachlinger 8279 (CAS).