Ophiopogon trigonantherus N.Tanaka & Aver., 2021

Nguyen, Khang Sinh, Tanaka, Noriyuki, Averyanov, Leonid V., Maisak, Tatiana V., Nguyen, Phuong Hanh & Tran, Duc Binh, 2021, Two new species, Ophiopogon dolichocaulis and O. trigonantherus (Asparagaceae), from northern Vietnam, Phytotaxa 523 (4), pp. 291-298 : 295-297

Ophiopogon trigonantherus N.Tanaka & Aver. , sp. nov. ( Fig. 3 )

Most similar to O. rupestris , but differs chiefly in its longer stem with slightly more distant annual clusters of leaves, leaves with fewer longitudinal veins, larger flowers, broader, more incrassate filaments, larger, more yellowish triangular anthers, and in flowering season.

Type: — Holotype ( LE 01049699 http://en.herbariumle.ru/?t=occ&ea=edit&id=4195) prepared on 19 April 2019 by L. Averyanov and T. Maisak from cultivated plant CPC 7574 / TM 1198 a (photo - LE 01122879 http://en.herbariumle.ru/?t=occ&id=99499), which was originally collected on 21 November 2014 by L. Averyanov et al. in: VIETNAM. Cao Bang Province: Bao Lac District , Hong An Municipality , Mi Lung Village , around point 22°49’15.4’’N 105°49’53’’E, at elevation 1500–1550 m a.s.l..

Description: —Herb terrestrial, evergreen, perennial. Stem erect, usually unbranched, to 20 cm tall, 1‒1.5(2) cm in diameter, densely imbricately covered with pale brown papyraceous wings of leaf sheath remnants, proximally with few rigid semi-woody prop roots. Leaves borne in several shortly distant clusters along stem, horizontally spreading or slightly arching, shortly petiolate; petiole rigid, thick, recurved, (1.5)2‒2.5(3) cm long, (1.5)2‒2.5(3) mm wide; blade oblong, broadly lanceolate or elliptic, often slightly oblique, acute, shortly acuminate or apiculate at apex, (5)7‒ 12(14) cm long, (1.8)2.2‒2.8(3.2) cm wide, entire, coriaceous, glabrous; adaxial surface uniformly dark green, main longitudinal veins 5‒7, secondary veins indistinct; abaxial surface with many longitudinal parallel narrow green veins (principal veins usually 17‒19, including outermost, marginal ones), intervein portions glaucous, white. Flowering stem slightly curved distally; peduncle erect, straight, 2‒2.5(3) cm long, 2‒2.5 mm in diameter, ebracteate, dark violet; inflorescence a short sublax raceme bearing 2‒3(4)-flowered fascicles in axils of bracts; rachis 2‒2.5(3) cm long, finely ridged. Bracts on rachis narrowly triangular, tapering to apex, (2.5)3‒5(6) mm long, (0.4)0.5–1(1.2) mm wide, green, often with violet tint in basal part; bracteoles subtending pedicel smaller, triangular, (0.4)0.5‒0.8(1) mm long and wide, dull light brownish, scarious along margin. Pedicels terete, (2.5)3‒5(5.5) mm long, (0.8)1(1.2) mm in diameter, slightly arching, white with light violet tint. Flowers cernuous, campanulate, (7)8‒9(10) mm long, (8)10‒ 11(12) mm across, odorless, enectariferous. Perianth proximally syntepalous, distally 6-lobed; basal stalky part of flower cylindric, slightly curved, white tinged with purple-violet; lobes subsimilar (outer 3 somewhat narrower than inner 3), slightly cymbiform, triangular ovate, obtuse to rounded, sometimes shortly apiculate, recurved, (5)5.5‒6.5(7) mm long, (3)3.5‒4(4.5) mm wide, thick, white tipped with violet. Androecium broadly conic; stamens 6, each inserted at base of perianth lobe; filaments short, broad, incrassate, white; anthers strongly connivent, distally often slightly recurved, triangular, subacute, 2.8–3 mm long, 2.4‒2.6 mm wide, introrse, bright greenish yellow (including dorsal connective). Pistil 1, tricarpellate; ovary inferior, obconoid, (5)5.5‒6(6.5) mm long, 4‒4.5 mm wide at top, 3-locular; each locule with 2 ovules at basal portion of ovary central axis; ovary top subtruncate, slightly convex above, but sunken in center around base of style; style erect, straight, cylindric, slightly narrowing toward apex, 5–6 mm long, 0.6–0.8 mm in diameter; stigma small, entire to indistinctly 3-lobed. Fruits (seeds) unknown.

Paratype: — VIETNAM. Cao Bang Province: Bao Lac District, Hong An Municipality, Mi Lung Village, primary broad-leaved and mixed humid evergreen forest (with Podocarpus , Pinus , Fokienia and Tsuga ) on very steep slopes and along rocky ridge composed of highly eroded, solid crystalline limestone at elevation about 1500–1550 m a.s.l. around point 22.816667°N 105.831389°E, terrestrial herb in shady wet place on rocky mossy mountain slope, not common, 21 November 2014, L. Averyanov, N.T. Hiep, N.S. Khang, T. Maisak, L. Osinovetz, CPC 7574 (Herbarium of Center for Plant Conservation, Hanoi).

Etymology: —The specific epithet is a Greek-derived adjectival compound, referring to the ‘triangular anthers’ unique to the new species.

Habitat and conservation status: —Occurs usually in shady wet places on very steep mossy slopes near mountain tops at elevations of 1500–1550 m a.s.l., which are composed of crystalline karstic limestone and covered with primary evergreen humid broad-leaved and mixed forest (with Podocarpus , Pinus , Fokienia and Tsuga ), not common. Estimated IUCN status – DD.

Phenology: —Flowers in cultivation in April–May.

Distribution: —Limestone areas in N Vietnam (Cao Bang Province, Bao Lac District).

Taxonomic relationships: — Ophiopogon trigonantherus is most closely similar to O. rupestris Aver. & N.Tanaka in Averyanov et al. (2013: 233) known from northern Vietnam (Phu Tho Province), but differs mainly in its stem to 20 (vs. to 10) cm long with slightly more distant annual clusters of leaves, petioles 1.5‒3 (vs. 4‒5) mm wide, leaf blades 5–14 × 1.8–3.2 (vs. 12‒20 × 3‒4.5) cm with 17–19 (vs. to ca. 27) longitudinal veins, flowers 8–12 (vs. 4–7) mm across, perianth lobes 5‒7 × 3‒4.5 (vs. 3‒4.5 × 2‒2.5) mm, more broadly conoid androecium, triangular (vs. narrowly lanceolate) anthers 2.8–3 × 2.4‒2.6 (vs. 2 × 0.5‒0.6) mm, and ovaries 5‒6.5 × 4‒4.5 (vs. 3.5‒4 × 2‒3) mm. In addition, the new species flowers in cultivation in April and May, whereas O. rupestris flowers in nature in September and October.

The new species is also close to Ophiopogon dracaenoides ( Baker 1874: 174) Hooker (1892: 268) , but readily distinguishable mainly by the stem to 20 cm long (vs. 65 cm or longer), shorter intervals between annual clusters of leaves, broader more incrassate filaments, and broader, triangular (vs. lanceolate) anthers (data on O. dracaenoides from Tanaka 2000b).

Figures

FIGURE 3. Ophiopogon trigonantherus. All photos (LE01122879) were made from living cultivated plant (CPC 7574 / TM 1198a) prior to preparation of the type specimen (LE01049699). Photos, correction and design by L. Averyanov and T. Maisak.