Ophiopogon sclerophyllus D. X. Nong

Ophiopogon sclerophyllus D. X. Nong & H. Z. L ü, sp. nov. (Fig. 1 & 2)

Diagnosis:— Ophiopogon sclerophyllus is morphologically similar to O. pseudotonkinensis, but differs markedly by its roots with fusiform or oblong tubercles, thickly leathery leaf blade, longer and slender inflorescence exceeding or as long as the leaves, smaller flowers with oblong, recurved perianth segments, separate anthers and 3-sulcate style.

Type:— CHINA. Guangxi Zhuang Autonomous Region, Hechi city, Donglan county, Sannong town, Shuangsu village. Collected in nature in November 2019 by H. Z. Lü (Garden number: 20190601). Type specimen prepared from a living cultivated plant in May 2022 by D. X. Nong 451224220527001 (holotype: GXMG!). The photographic plates in Fig. 2 were prepared from the same plant as the holotype.

Description: —Herb terrestrial, perennial, completely glabrous. Rhizome shortly many branched, with numerous brownish roots. Roots 1–1.5 mm in diam., pubescent, usually with fusiform or oblong tubercles near middle or tip. Sheath leaves 3–5, 1.5–7 cm long, 1–1.2 cm wide, wings of margins scarious, white; Leaves 8–12, thickly leathery, linear-oblanceolate, 15–40 cm long, 0.7–2.2 cm wide, slightly oblique, basal part gradually narrowed into petiolelike, apex rounded to obtuse and emarginate at tip, entire margins reflexed when dry; adaxially glossy, uniformly dark green, abaxially light green, with 7–14 parallel narrow white stripes; main longitudinal veins indistinct, numerous; secondary veins hardly visible. Inflorescence a lax raceme with distant fascicles of 2–4 pedicellate flowers; peduncle erect, slightly flattened, 2(3)-edged or angled, 14–22.5 cm long, 2–3 mm in diam., dull greenish to dull brownishpurple; rachis flattened and obscurely ridged, 6–19.5 cm long. Bracts narrowly triangular, acuminate, green, scarious at margins; bracts on main axis 4–14 mm long, 2–5 mm wide; flower-subtending bract similar to bracts subtending cymes, but much smaller. Flowers light violet to white, drooping, widely opening, 10–12 mm in diam., fragrant. Pedicel terete, arising from bracteal axils, violet, 4–5 mm long, 0.5–0.6 mm in diam., as long as stalky part of floral base, straight or curved distally, jointed to floral base forming a distinct articulation. Perianth segments 6, in 2 whorls, subsimilar, fleshy, oblong, recurved, rounded at apex, 4.5–5 mm long, 2–2.3 mm wide, outer segments slightly longer than the inner ones, externally pale violet, internally whitish. Stamens 6, located at base of each perianth segment, separate; anthers 6, light green, shortly stalked, introrse, narrowly conical, 2.5‒3 mm long, 0.5‒0.6 mm wide, apically acute; filaments shortly conoid, fleshy, 0.6–0.8 mm long and wide, white. Ovary inferior, 3-locular, almost flat or slightly convex at apex, 2–3 ovules on basal placenta in each locule. Style purely white, 4.5–5 mm long, 0.6–0.8 mm in diam. at base, exceeding anthers, narrowing distally, distinctly curved near the middle, 3-sulcate; stigma indistinctly minutely 3-lobed. Mature seeds suborbicular, 7‒8 mm long, 6‒7 mm in diam., glossy bluish-green.

Paratype:— CHINA. Guangxi Zhuang Autonomous Region, Hechi city, Donglan county, Sannong town, Shuangsu village, primary evergreen broad-leaved forest near the top of a limestone mountain, alt. 527 m, rare, 2 November 2019, H. Z. Lü et al. 451224191102026LY (GXMG!); the same locality, 21 November 2022, D. X. Nong 451224221121001 (GXMG!)

Etymology:— The specific epithet is derived from the thickly leathery leaf blade of the species. Chinese name is proposed here as “üfiffiĸạ”.

Ecology, phenology and conservation status:— This new species grows on limestone slopes along the Hongshui River (Fig.1), under primary evergreen broad-leaved forest at elevations 500–527 m a.s.l., in shady places, rare. Flowering in cultivation in May–June. Since our current knowledge on the distribution is very limited, the conservation status of O. sclerophyllus is assessed here as Data Deficient (DD), following the guidelines in the IUCN Red List Categories and Criteria ver. 14 (IUCN 2019).

Distribution:— Ophiopogon sclerophyllus is known only from the type locality. Although we have been conducting fieldwork in its surrounding areas for more than 3 years, no other population had been found in similar habitats. Presumably it is a local endemic of limestone areas in Guangxi, China.

Similar species:— Ophiopogon sclerophyllus is morphologically similar to O. pseudotonkinensis, but differs the latter markedly by its thickly leathery leaf blade (vs. papery leaf blade), longer and slender inflorescence exceeding or as long as the leaves, raceme with more flowers, smaller flowers with more strongly expanded, recurved perianth segments, free anthers (vs. connate anthers), 3-sulcate styles (vs. fine cone style), and flowering (in cultivation) in May (vs. September). It is also resembles O. petraeus Averyanov & N. Tanaka in Averyanov et al. (2015a: 30) described from northern Vietnam by having linear-oblanceolate leaf blade, but is distinguishable chiefly by the shorter pedicel (4–5 mm vs. 6–16 mm), oblong, recurved perianth segments (vs. ovate, distally slightly recurved perianth segments), and flowers under cultivation in May (vs. September–October). In addition, Ophiopogon sclerophyllus differs from the similar species by its roots with tubercles. Details of the morphological differences amongst O. sclerophyllus, O. pseudotonkinensis and O. petraeus are presented in Table 1.