Boechera rollei (Rollins) Al-Shehbaz, Novon 13: 389. 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 : 31-32

Boechera rollei (Rollins) Al-Shehbaz, Novon 13: 389. 2003 Figures 3 , 8

Arabis rollei ≡ Arabis rollei Rollins, Harvard Pap. Bot. 4: 43. 1993. Type: U.S.A. California. Siskiyou County: Divide between the Applegate and Klamath rivers, Red Butte-Kangaroo Mt, Lilypad Lake -Towhead region, 4 Aug 1983, W.E. Rolle 831 (holotype: GH!; isotypes: JEPS!, MO). GH holotype image - http://kiki.huh.harvard.edu/databases/specimen_search.php?mode=details&id=67660

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 from centre of basal rosettes, glabrous throughout. Leaves at stem bases oblanceolate, 3-8 mm wide, entire, ciliate proximally with 1-3 rayed trichomes 0.2-0.7 mm, blade surfaces glabrous or sparsely pubescent with short-stalked, 2-4 rayed trichomes 0.2-0.4 mm; cauline leaves 6-12, occasionally concealing stem proximally, the uppermost glabrous, with auricles 0.5-2.5 mm. Inflorescences unbranched, 3-7 flowered; fruiting pedicels 4-8 mm, arched, curved proximally (not geniculate), glabrous. Flowers divaricate-ascending at anthesis; sepals glabrous; petals creamy-white and occasionally blushed lavender, 8-11 mm long × 2.0-2.5 mm wide, glabrous; anthers with mostly well formed, narrowly ellipsoid, symmetrically tricolpate pollen; ovules 14-22 per fruit. Fruits 35-65 mm × 2.0-3.5 mm, pendent to reflexed, not appressed to rachises, often secund, straight to somewhat curved, with undulate edges, glabrous; apical angle of fruit valve <25° (measured from base of style to 5 mm proximate); style persistent 0.6-1.2 mm. Seeds uniseriate, 3-4 × 1.5-2.0 mm; wing distal and proximal, 0.3-0.6 mm wide.

Distribution, habit and phenology.

Populations of B. rollei are known from the Klamath Mountains Province primarily in the vicinity of Lilypad Lake in Siskiyou County, California. However, a single individual from Beaver Creek in Jackson County, Oregon has been confirmed morphologically and genetically as B. rollei . It is noteworthy that the collector of this specimen (F.W. Hoffman 2551) mentioned that it came from serpentine soil, to which B. rollei appears to be restricted. The species is often associated with Pinus jeffreyi and Calocedrus decurrens on sparsely forested slopes at elevations of 1600-1800 m; flowering June-Aug.

Comments.

Boechera rollei is distinguished from the three S2X clusters of B. suffrutescens s.l. by its showier flowers with longer (8.0-11.0 vs. 4.5-6.0 mm) petals and narrower (0.3-0.6 vs. 0.8-1.5 mm) seed wings. It is easily distinguished from B. constancei by its markedly auriculate cauline leaves, shorter (0.6-1.2 vs. 1.5-5.5 mm) styles and lack of herbage with bluish cast.

Specimens examined.

California. Siskiyou County: Below the Pacific Crest Trail on the W side of Lilypad Lake, ± 0.5 mile S of Red Butte, ± 5.5 miles N of Seiad Valley, Siskiyou Mountains, Rogue River National Forest, 24 Jul 2008, P.J. Alexander 869 A, D, E (DUKE), C, D, E (NMC); On the Pacific Crest Trail ± 0.7 miles SSW of Cook and Green Pass, ± 1.9 miles E of Red Butte, ± 7 miles NNE of Seiad Valley, Siskiyou Mountains, Rogue River National Forest, 17 Apr 2009, P.J. Alexander 873 (MO), A, B, C (NMC); 0.1 mi SW of border between Siskiyou National Forest and Klamath National Forest. NE facing slope above Lilypad Lake on Pacific Crest Trail. 0.7 air miles SSW of Red Butte summit. 1/ 4 mi SW of Lilypad Lake, 29 Jun 2012, D.P. Morin 13 A, B (NMC) (these represent the DNA vouchers for samples A - O); Divide between the Applegate and Klamath Rivers, Red Butte-Kangaroo Mt.-Lilypad Lake-Towhead Lake region (T47N, R12W, S13), 8 Apr 1983, W.E. Rolle 831 A - D (GH), A (JEPS); Red Buttes Wilderness Area about 3/ 5 mi S of Towhead Lake, or ½ W of Lily Pad Lake. T47N R12W Sec. 13 NW1/4 of SW1/4., 8 Apr 2009, W.E. Rolle 1538 (DUKE); Near Lilypad Lake, Red Butte and Kangaroo Mt., 27 Aug 1985, W.E. Rolle s.n. (TEX), (GH), A, B (JEPS), A, B (CAS). Oregon. Jackson County: Upper Beaver Creek, 10 Jul 1948, Hoffman 2551 (UC).

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 8. Boechera rollei, Rolle s. n. (CAS).