Sabulina basaltica B.S.Legler, 2017

Legler, Ben S. & Dillenberger, Markus S., 2017, Two new species of Sabulina (Caryophyllaceae) from Washington State, U. S. A., PhytoKeys 81, pp. 79-102 : 82-86

Sabulina basaltica B.S.Legler sp. nov. Figs 2A -E , 3

Type.

U.S.A. Washington, Clallam Co.: Olympic National Park: along climbers trail at base of summit block on west side of Mt. Angeles , 1872 m, 47.995079°N, 123.468522°W, 15 Jul 2016, B.S. Legler 14177 (holotype: WTU!; isotype: OLYM!) .

Diagnosis.

Differs from all other glabrous, perennial Sabulina species in North America by the combination of 3-veined dried leaves, flowers partly in 2-5(-8)-flowered cymes, sepals mostly <3 mm long, petals conspicuously longer than the sepals, capsules 1.8-2.4 mm long and mostly <or = sepals, and dark reddish-brown to reddish-black seeds 0.6-0.8 mm long.

Description.

Plants perennial, forming dense (rarely loose) mats or cushions 2-8(-12) cm diameter, glabrous throughout. Taproot slender to slightly thickened, 1-3 mm diameter near summit. Stems numerous, radially spreading from the taproot, prolifically branching; older stems decumbent to ascending, 1-6 cm, brown to tan; new shoots arising from axillary fascicles on previous year’s stems, ascending to erect, 0.5-3 cm, internodes of flowering shoots 0.1-1(-2) times as long as leaves, light green or maroon-tinged. Leaves usually strongly overlapping, occasionally well-spaced, connate proximally to form a tight, scarious sheath; blade (0.6-)1-3.5(-4.5) × 0.3-0.6 mm, ascending to nearly appressed, straight to slightly incurved or slightly recurved, light green to yellowish-green, not or only weakly shiny, subulate, rounded abaxially, nearly flat adaxially, veins not visible in fresh material, margins rounded, not scarious, smooth, apex obtuse to rounded, usually maroon; axillary fascicles of leaves usually present; previous year’s leaves marcescent, long-persistent on older stems, with the midvein and two lateral veins becoming prominent, rigid. Inflorescences terminal, 2-5(-8)-flowered, open cymes usually mixed with solitary terminal flowers; bracts 1.1-2.6 mm, subulate to lanceolate, incurved, green with scarious margins, rounded abaxially, flat to concave adaxially, apex obtuse to bluntly acute. Pedicels 1-3.5(-6) mm, glabrous. Flowers perfect or functionally male or functionally female, many plants functionally monoecious to nearly dioecious. Hypanthium obscure, disc-shaped. Sepals spreading-ascending at anthesis, light green, glabrous, lanceolate to narrowly ovate-lanceolate, (1.6-)2.4-2.8(-3.3) × 0.7-0.9(-1.1) mm, (2.4-)3-3.2(-3.5) times as long as wide, scarious margins ca. 0.05-0.2 mm wide, base cupped, apex green to maroon, acute to shortly acuminate, outer surface flat to convex, weakly 3-veined at anthesis, becoming distinctly 3-veined in fruit or when dried. Petals white, spreading, narrowly to broadly oblong or narrowly obovate, 3.2-5.2 × 1.1-2 mm, (1-)1.2-1.8(-2) times as long as sepals, base gradually tapered to a short, greenish-yellow claw, apex rounded to truncate, entire to weakly erose or slightly emarginate. Nectaries 5, at base of outer stamens, greenish-yellow, ca. 0.4 × 0.4 mm, truncate, alternate with the petals. Stamens 10, in 2 series of 5, either all fertile or all abortive; filaments subulate, whitish-green; anthers orbiculate, pale yellow; fertile stamens with filaments 1.4-2.5 mm and anthers 0.4-0.5 mm; abortive stamens with filaments 0.2-0.5 mm and anthers 0.1-0.2 mm. Ovary superior; placentation shortly free-central; ovules usually 12 per ovary. Styles 3, distinct, erect to ascending; functionally male flowers with styles ca. 0.7 mm and stigmas scarcely developed; functionally female flowers with styles 1-1.7 mm and stigmas linear, glandular-puberulent adaxially. Capsules light green to greenish-tan (valve margins tan), on stipe ca. 0.1-0.2 mm, ovoid-conical, 1.8-2.4 × 1-1.5 mm, slightly shorter than or equaling (rarely slightly longer than) and usually enclosed by the appressed sepals and withering-persistent petals, dehiscing in upper half by 3 valves, these becoming incurved on margins and slightly recurved at tip. Seeds 4-8 per capsule, 0.6-0.8 mm, dark reddish-brown to reddish-black, obliquely reniform with radicle prolonged into a curved bump, somewhat compressed, with rounded margins, surfaces sculpted with low, rounded, slightly elongate and sinuous bumps at> 10 × magnification.

Additional specimens examined.

U.S.A. Washington, Clallam Co. Third Peak, Mt. Angeles, 10 Aug 1911, no collector (OLYM); Mt. Angeles, 5500 ft, 2 Aug 1930, J.W. Thompson 5481 (WTU); Mt. Angeles , 5500 ft, 10 Jul 1931, G.N. Jones 3202 (WTU); Mt. Angeles , 6800 ft, 17 Jul 1931, J.W. Thompson 7433 (WTU); Mt. Angeles , 5500 ft, 15 Jul 1933, J.W. Thompson 9458 (WTU); Mt. Angeles , 15 Jul 1933, H.E. Helmrich 259 (WTU); Mt. Angeles , 12 Jul 1936, M.P. Harthill s.n. (OLYM); Mt. Angeles , 31 Jul 1966, L.C. Bliss s.n. (WTU); Saddle between Mt. Baldy and Mt. Tyler, 5600 ft, 23 Jul 1976, N. Buckingham 514 (OLYM); Blue Mountain , northeast ridge, T28N R5W S1, 5600 ft, 31 Jul 1984, E.L. Tisch 2724 (OLYM); Blue Mountain , northeast ridge, T28N R5W S1, 5600 ft, 31 Jul 1984, E.L. Tisch 2724 1/2 (OLYM); Along ridgeline ca. 100 meters southwest of summit of Mt. Angeles , 47.994735°N, 123.467501°W; 1896 m, 15 Jul 2016, B.S. Legler 14178 (WTU); High point at east end of ridgeline along summit of Mt. Angeles , 47.995365°N, 123.463590°W; 1949 m, 15 Jul 2016, B.S. Legler 14179 (WTU); Southeast rib of Steeple Rock along Hurricane Ridge, 47.961464°N, 123.452969°W; 1657 m, 16 Jul 2016, B.S. Legler 14183 (WTU); South side of summit of Eagle Point, along Hurricane Ridge, 47.938951°N, 123.409042°W; 1893 m, 16 Jul 2016, B.S. Legler 14184 (WTU, OLYM) ; Jefferson Co.: Iron Mountain, 6000 ft., 21 Jul 1934, J.W. Thompson 11054 (WTU); Ridge north from Buckhorn Pass, T 27N R4W S13, 6600 ft, 1 Aug 1981, N. Buckingham 2658 (OLYM); West face of Buckhorn Mountain just above ridgeline that connects Buckhorn Mountain to Peak 6988, 47.826286°N, 123.117615°W; 2026 m, 24 Jul 2016, B.S. Legler 14195 (WTU) .

Etymology.

The epithet basaltica refers to the basalt rock to which this species is apparently restricted.

Vernacular name.

Suitable common names are Olympic sandwort or basalt sandwort.

Distribution and ecology.

Sabulina basaltica is known only from subalpine and alpine peaks along the northeastern rim of the Olympic Mountains in Clallam and Jefferson counties, Washington, U.S.A. (Fig. 6C ), at documented elevations of 1650-2100 meters. It is presently known from seven peaks: Mt. Angeles, Steeple Rock, Eagle Point, Blue Mountain, near Mt. Tyler, Buckhorn Mountain, and Iron Mountain. It is apparently confined to south or southwest facing rock faces composed of ocean floor basalts (mainly pillows and breccia) of the Crescent Formation ( Tabor and Cady 1978, Babcock et al. 1992) on ca. 30-60° slopes (Fig. 5A ). Sabulina basaltica occur as scattered individuals forming small tufts in exposed rock crevices with very sparse vascular plant cover (Fig. 5B-C ). The rock faces are exposed to solar radiation and wind. Snow accumulation is likely minimal due to wind ablation, and meltout likely occurs much earlier than on adjacent slopes. No plants were found on more protected east or north facing slopes, nor on more gentle slopes around the periphery of rock faces, whether vegetated or not.

Directly associated species include Anemone multifida Poir., Antennaria cf. rosea Greene, Campanula piperi Howell, Carex nardina Fr., Dasiphora fruticosa (L.) Rydb., Erigeron compositus Pursh, Penstemon davidsonii Greene var. menziesii (D.D. Keck) Cronquist, Petrophytum hendersonii (Canby) Rydb., Phlox diffusa Benth., Polemonium pulcherrimum Hook. subsp. pulcherrimum , Potentilla villosa Pall. ex Pursh, Sabulina rubella (Wahlenb.) Dillenb. & Kadereit, Salix nivalis Hook., Saxifraga austromontana Wiegand, Saxifraga cespitosa L., Sedum lanceolatum Torr., Selaginella wallacei Hieron., Smelowskia americana Rydb., Trisetum spicatum (L.) K. Richt., and Viola flettii Piper. Crustose lichens cover most of the rock surfaces. Adjacent conifer species at subalpine sites include Callitropsis nootkatensis (D. Don) D.P. Little, Abies lasiocarpa (Hook.) Nutt., Juniperus communis L. var. kelleyi R.P. Adams, and Pinus albicaulis Engelm.

Although oceanic basalts form an extensive belt around the northern, eastern, and southeastern sides of the Olympic Mountains ( Tabor and Cady 1978), suitable climatic conditions for S. basaltica presumably occur only in the northeastern portion of the mountains within a rain shadow formed by one of the steepest precipitation gradients in North America ( Phillips and Donaldson 1972). Average annual precipitation levels for Mt. Angeles and Buckhorn Mountain are estimated at ca. 200 cm ( PRISM 2017). For comparison, Mt. Olympus, only 28 km to the southwest of Mt. Angeles, receives an estimated 600 cm of precipitation annually and Sequim, 30 km to the northeast, only 41 cm of annual precipitation ( PRISM 2017). Furthermore, the growing season is relatively dry, with ca. 12% of total annual precipitation falling during May-September at Mt. Angeles ( PRISM 2017). Based on climate and substrate, areas of suitable habitat for S. basaltica are prediced to occur in a discontinuous arc extending from the vicinity of Hurricane Ridge in the north to at least the vicinity of Mt. Constance to the southeast, and possibly farther south to The Brothers and adjacent peaks (Fig. 6C ). Basalts of the Crescent Formation reappear on the southern tip of Vancouver Island, British Columbia, just to the north of the Olympic Mountains ( Babcock et al. 1992), though at much lower elevations where previously covered by the Cordilleran ice sheet; we do not expect S. basaltica to occur there.

A pair of specimens from Blue Mountain, Clallam County (E. L. Tisch 2724 and E. L. Tisch 2724 1/2, OLYM) indicate on the label that plants were collected from "crevices in (limestone?) rock outcrop," raising the possibility that S. basaltica is not confined to basalt. However, Blue Mountain contains outcrops of basalt rocks and a return visit to the site would be needed to determine the actual rock type from which the specimens were collected.

Phenology.

Specimens of Sabulina basaltica with flowers were collected from mid July to mid August, and specimens with fruits from mid July to early August.

Conservation status.

Population sizes on Mt. Angeles, Steeple Rock, and Eagle Point were estimated at ca. 1000, 100, and 300 plants, respectively, during visits in 2016. No estimate was attempted at Buckhorn Mountain due to difficulty of access, but about 30 plants were observed in the immediate vicinity of Legler 14195. Significant areas of potentially suitable habitat occur on other basalt peaks in the northeastern Olympic Mountains within a predicted area of extent of ca. 50 km2; however, the vascular plant flora for the majority of these peaks remains poorly documented or undocumented with herbarium specimens ( CPNWH 2017), and the lack of information precludes range-wide estimates of the total number of populations and plants. Assignment of a formal conservation status may require additional field work to gauge rarity. All known populations and nearly all areas of potentially suitable habitat are protected within Olympic National Park and adjacent wilderness areas. The known populations are located on steep rock slopes away from trails and roads. Therefore, direct anthropogenic impacts are assumed to be minimal. Grazing pressure and disturbance from introduced mountain goats ( Oreamnos americanus Blainville, 1816) pose an increasing impact to high elevation plant communities in the Olympic Mountains ( Houston et al. 1994, Jenkins et al. 2012), and goats were observed in the vicinity of populations of S. basaltica on Mt. Angeles during the visit in 2016; however, no evidence of direct grazing or damage to S. basaltica was detected.

Figures

Figure 2. Line drawings of Sabulina basaltica and Sabulina sororia. A-E. Sabulina basaltica. A Habit B Dried leaf with 3 veins C Cymose, bracteate inflorescence with two flowers D Capsule with dried, 3 - veined sepals (with sepals pushed outwards and withered petals removed to reveal capsule) E Seed F-I Sabulina sororia F Habit G Dried leaf with 1 vein H Flower I Capsule with dried, 3 - veined sepals (withered petals removed).

Figure 3. Sabulina basaltica. A Plant forming a tight mat (Legler 14178) B Excavated plant with taproot (Legler 14184) C Fresh leaves and persisting, 3 - veined, dead leaves (Legler 14177) D Dead, persisting, 3 - veined leaves (Legler 14178) E-F Cymose inflorescences (Legler 14177, Legler 14175) G Solitary terminal flower (Legler 14184) H Sepals and petals, showing shapes and lengths (Legler 14184) I-J Flowers with different combinations of stamen and style lengths (Legler 14177, Legler 14184) K Partially dissected flower showing hypanthium and nectaries (Legler 14183) L Dehisced capsule with seeds (Legler 14183) M Seeds (Legler 14183). Black scale bar is 1 mm.

Figure 5. Representative habitats. A-C Sabulina basaltica habitat A Basalt slope near the type locality (Legler 14177) B-C Plants in crevices of basalt rock faces (Legler 14177, Legler 14183) D-F Sabulina sororia habitat D Reddish-colored dunite slope at the type locality (Legler 14263) E-F Plants among dunite rock and gravel (Legler 14263, Legler 14268).

Figure 6. Distribution of Sabulina basaltica and S. sororia. A-B Reference maps of western North America and Washington State, indicating locations of inset maps C Known locations for Sabulina basaltica (open black circles) within the northeastern Olympic Mountains; gray shading indicates the predicted extent of potential habitat based on exposures of oceanic basalt rocks at subalpine to alpine elevations D Known locations for Sabulina sororia (open black squares) within the Twin Sisters Range; gray shading indicates the predicted extent of potential habitat based on exposures of dunite rock away from large snowfields at subalpine to alpine elevations.