Peliosanthes virescens Aver., V.C.Nguyen, N.Tanaka & K.S.Nguyen, 2023

Averyanov, Leonid V., Nguyen, Van Canh, Tanaka, Noriyuki, Nguyen, Khang Sinh & Maisak, Tatiana V., 2023, Three new taxa and two noteworthy species of Peliosanthes (Asparagaceae, Convallarioideae) from Laos and Vietnam, Phytotaxa 609 (3), pp. 209-221 : 218

Peliosanthes virescens Aver., V.C.Nguyen, N.Tanaka & K.S.Nguyen , sp. nov. ( Fig. 4 )

Diagnosis: —Most similar to P. argenteostriata , but differs mainly by the rhizome with subterranean stolons, non-striated leaf blades, narrowly open spherical flowers, incurved, apically rounded, largely imbricate greenish white perianth segments, a nearly flat pale green staminal corona, and a broadly conic, three-ridged, greenish white pistil.

Type: — VIETNAM. Dak Lak Province: Ea’Hleo District, Ea’Hiao Village, evergreen forest at an elevation of about 900 m a.s.l., 1 February 2023, V. C. Nguyen s.n., type herbarium specimens prepared from cultivated plants, 18 February 2023, V. C. Nguyen, L. Averyanov, AL 2037 . Holotype LE: LE01170311 (https://en.herbariumle.ru/?t=occ&id=166030). Isotype LE: LE01170312 (https:// en.herbariumle.ru/?t=occ&id=166038). Photos of the cultivated plants used for preparing the type specimen— LE: LE01123812 (https://en.herbariumle.ru/?t=occ&id=165101).

Etymology: —The specific epithet refers to the greenish flowers.

Description:—Herb terrestrial, rhizomatous, acaulescent, evergreen perennial. Rhizome clumpy or tuberous, 0.5– 1(1.5) cm long, (4)5–6(7) mm in diameter, covered with few remnants of papyraceous, whitish bracts, producing whitish subterranean stolons becoming over 10 cm long. Roots several, rigid, fleshy, orange brown. Stem ascending or erect, 1–1.5 cm high, covered with few remnants of whitish herbaceous bracts. Leaves distinctly petiolate; petiole rigid, usually suberect or slightly curved, (8)10–14(16) cm long; leaf blade narrowly ovate to elliptic, (7)8–12(13) cm long, (2)2.5–4.5(5) cm wide, somewhat rugose, leathery, glabrous, glossy, dark green above, light green beneath, shortly acuminate, with many longitudinal veins; secondary transverse veinlets numerous, indistinct, nearly perpendicular to longitudinal veins. Flowering stem (peduncle and inflorescence rachis) erect, much shorter than leaves, (5.5)6–7(7.5) cm long; peduncle (2.6)2.8–3.8(4) cm long, 1.8–2.2 mm in diameter, stout, light green, bracteate; sterile bracts on peduncle (1)2–3(4), broadly triangular, acuminate, clasping, papyraceous-membranous, whitish, (7)8–1.2(1.4) cm long, (4)6–8(10) mm wide; rachis (1)1.5–2.5(3) cm long, bearing (4)6–8(10) flowers in raceme. Floral bracts 2 (outer bract and inner bracteole) at base of pedicel, whitish, papyraceous-membranous, narrowly triangular, tapering to acute apex; bract borne below flower, (4)5–7(8) mm long, (1.2)1.4–2(2.2) mm wide; bracteole borne crosswise to bract, twice smaller. Pedicel ascending, cylindric, 1.6–2.2 mm long, light green. Flowers blooming acropetally, solitary in axils of bracts, subsessile, nearly horizontal, spherical, narrowly open, (5)5.5–6(6.5) mm high, (6.5)7.5–8(8.5) mm wide, light greenish. Perianth distally 6-cleft; tube broadly bowl-shaped, 1–1.2 mm high, 4.5–5 mm in diameter; segments 6 in 2 whorls of 3, imbricate except distal portion, incurved, broadly ovate or almost circular, with rounded and scarcely recurved apex, abaxially convex, hyaline along margins, fleshy; outer 3 segments 5.5–6 mm long, 4.5–5 mm wide; inner ones 4.5–5 mm long, 4–4.2 mm wide. Corona nearly flat to slightly raised centrally (distally), less than 0.5 mm high, hexagonal at base, (4.4)4.6–5(5.2) mm in diameter, inside below each anther obtusely thickened longitudinally, apical opening almost circular, 2–2.2 mm in diameter. Anthers 6, sessile, introrse, nearly circular, 0.5–0.6 mm long and wide, light beige; pollen cream white. Pistil half-inferior, distal free part broadly conic, 1.4–1.6 mm high, 2.8–3 mm across at base, with 3 low longitudinal ridges decurrent from stigmatic lobes, pale greenish white; ovary hexagonal or stellate at base, internally incompletely 3-septate, each locule containing 4(6) ovules on central basal placentae; stigma 3-dissected, lobes narrowly obovate, tri-radially spreading, 0.2–0.3 mm long. Fruits unknown.

Ecology and phenology: —Occurs in primary or aged secondary submontane evergreen broad-leaved forests at an elevation of about 900 m a.s.l. Flowers in February–March.

Conservation status: — Only a few mature individuals of this species were found in the type locality. For lack of sufficient data on the occurrence, we estimate the conservation status of the new species as “Data Deficient” ( DD), following the guidelines of IUCN (2022) .

Distribution: — Vietnam, Dak Lak Province (Ea’Hleo District). Currently known only from the type locality.

Taxonomic relationships: —In having comparatively small habit, small leathery glossy somewhat rugose leaf blades (6–13 × 2–5 cm) and a short inflorescence (rachis 1–3 cm long) with subsessile flowers (pedicels up to 2.2 mm long), Peliosanthes virescens is morphologically close to P. argenteostriata , P. convallarioides and P. nivea . These four species are confined in distribution to central Vietnam and Laos. Unlike P. virescens , P. argenteostriata and P. convallarioides , Peliosanthes nivea is unique within these four species in having different coloration of adaxial (dark purple) and abaxial (white to greenish white) sides of perianth segments. Then, P. virescens is closer to P. argenteostriata than to P. convallarioides in having apically rounded segments, since the latter has more acute outer perianth segments. In addition, P. virescens is distinguishable from these three species by having subterranean stolons, narrowly open spherical greenish white flowers, incurved, apically rounded perianth segments, a nearly flat (or only slightly convex) greenish white staminal corona, and a broadly conic (or trihedral) three-ridged greenish white pistil.

Figures

FIGURE 4. Peliosanthes virescens. A. Habit of flowering plant. B. Leaves, adaxial side (left) and abaxial side (right). C. Basal part of flowering plant. D. Inflorescence. E. Flowering stem. F. Front view of flower on rachis. G. Flower with perianth segments detached, front view. H. Flower with perianth segments detached, rear view. I–K. Flowers, longitudinally sectioned. L. Distal part of ovary crosssectioned, view from underside. M. Corona and pistil, view from above. N–P. Pistils with corona removed, views from various angles. Q. Middle part of ovary, cross-sectioned. R. Corona, view from above. Photos, photo correction, and plate design by L. Averyanov and T. Maisak, type specimen V.C. Nguyen, L. Averyanov, AL 2037.