Rhapis vidalii Aver., T.H.Nguyên & P.K.Lôc, Palms (1999+) 50: 12 (2006)

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Distribution

Map uses TDWG level 3 distributions (http://www.nhm.ac.uk/hosted_sites/tdwg/geogrphy.html)
Vietnampresent (World Checklist of Arecaceae)B
Species endemic to northeastern part of North Indochinese floristic province (Averyanov et al. 2003a, b). Vietnam: Hoa Binh prov. (Mai Chau district), Thanh Hoa prov. (Ba Thuoc and Quan Hoa districts). (L.V. Averyanov & N. Tien Hiep & P. Ke Loc, Rhapis vidalii, A New Papyrus-like Palm from Vietnam. 2006)A

Discussion

  • The species differs from all known species of Rhapis L.f. (Hastings 2003) in the extreme development of the stalk-like base of the corolla, formed by the fusion of the corolla to the receptacle. This type of pedicelliform corolla is known in other species of the genus such as Rh. micrantha (Beccari 1931, Dransfield pers. com.) but is nowhere so strongly developed as in this new species. After anthesis the cylindrical or narrowly conical deep green stalk-like corolla base becomes larger and bears on its widened apex a spherical, broadly obovoid or broadly ellipsoid drupe and 1–2 aborted carpels, which later degenerate. Eventually the solitary, juicy, milky-white fruit terminates the thick woody deep green stalk, having some superficial resemblance with the fleshy seeds of Podocarpus (Podocarpaceae). (L.V. Averyanov & N. Tien Hiep & P. Ke Loc, Rhapis vidalii, A New Papyrus-like Palm from Vietnam. 2006)A

Diagnosis

  • habitu subherbaceo eleganti, inflorescentia pauciramosa pendula filiformi, nec non floribus pedicellatis pendulis componente incrassato lignificato, cui ex parte axis floralis inter calycem et corollam locata formatus est.
    DIAGNOSTIC FEATURES. From all other species of the genus it differs in slender subherbaceous habit, filiform pendulous few branched inflorescence and pendulous pedicellate flowers with thick woody stalk-like corolla base developing from flower axis between calyx and corolla. (L.V. Averyanov & N. Tien Hiep & P. Ke Loc, Rhapis vidalii, A New Papyrus-like Palm from Vietnam. 2006)A

Biology And Ecology

  • FLOWERING PERIOD. Flowers and ripe fruits were observed in December. ECOLOGY. Terrestrial semi-woody undershrub 0.5–1.5(2) m tall. Primary and secondary evergreen closed seasonal broad-leaved lowland and submontane rather dry forests on steep rocky slopes of remnant ridges and hills composed of marble-like crystalline, highly eroded limestone at elevations 300–700(800) m a.s.l. RELATED SPECIES. In flower structure, the species most resembles Rh. micrantha but vegetatively it is very distinctive. (L.V. Averyanov & N. Tien Hiep & P. Ke Loc, Rhapis vidalii, A New Papyrus-like Palm from Vietnam. 2006)A

Etymology

Description

  • Sub-herbaceous undershrub with slender erect or slightly flexuous reed-like stems arranged commonly in loose groups with 3–6(10) individual growths of varying height. Stem very slender, unbranched, (0.3)0.5–1.5(2) m tall, 3–5 mm wide, with internodes 5–8(10) mm, covered in upper part with old leaf sheaths, terminated by a crown of 5–8(10) leaves, old stems bare in basal portion. Leaf sheaths narrow, 4–6 cm long, 4–6 mm wide, clasping and densely enveloping stem, their margins surrounding stem with a net of numerous flexuous anastomosing light yellowish-brown thin soft fibers; ligule broad, 1–2 cm long, light dull yellowish-brown, thin, papyraceous, early disintegrating into thin soft fibers. Petiole narrow, very slender, 15–20 cm long, about 1 mm broad, slightly curved at the base, ± straight toward the lamina, smooth along the margin, slightly flattened. Lamina suborbicular to fan-shaped (when young) in outline, 20–30 cm across, palmately segmented from near the base into 6–8(10) segments, each segment linear to narrowly lanceolate, grasslike, 12–18(20) cm long, (2)3–5(6) mm wide, sparsely finely denticulate along the margins, commonly with 2 prominent longitudinal veins, longitudinally folded, sometimes slightly narrowing to the apex, irregularly toothed, with 2–3 unequal, short acute apical lobes; adaxial hastula semicircular or broad half-elliptic, erect, hairy on young leaves with numerous light yellowish-gray to dull yellowbrown soft, thin caducous hairs, on old leaves glabrous. Inflorescence 1(2), interfoliar, near the apex of the stem, sparsely and laxly branched, pendulous 20–30 cm long, with light dull brownish narrowly lanceolate smooth, glabrous basal bract 6–12(14) cm long, 3–4(6) mm wide; peduncle 6–12(14) cm long, 0.6–1 mm wide with 1–2 narrowly lanceolate bracts, 2–6 cm long, 1.5–2.5 mm wide; rachis very narrow, in apical portion filiform, 0.3–0.7 mm wide, flexuous, with (1)2–6(10) rachillae, each with filiform yellowish bracts at the base, 4–7 mm long, 0.2–0.3 mm wide; rachillae 3–8(10), flexuous, each with 1–14 distant, shortly pedicellate flowers; pedicels (0.6)0.8–1.4(1.6) mm long, 0.2–0.3 mm wide, at the base with filiform, narrowly triangular acuminate bract 1–1.5 mm long, 0.1–0.2 mm wide, at the apex bearing flower, jointed with thick articulation. Flowers unisexual, solitary, spirally arranged and 3–10 mm distant on rachillae, staminate and pistillate superficially similar; flower axis between attachment of sepals and petals developed into prominent thick, woody, deep green, cylindrical stalk, narrowing to the base, 5.5–7 mm long, about 1–1.6 mm wide at the middle; staminate flower with calyx campanulate, glabrous, dull light yellowish-brown, papyraceous, tubular in basal two thirds 1.2–1.4 mm long, 0.5–0.7 mm wide, at the apex with 3 free, broadly triangular, lobes, 0.5–0.7 mm long, 0.7–0.8 mm wide at the base, slightly incurved, acute to acuminate, outside sometimes indistinctly keeled; corolla broadly campanulate, petals 3, glabrous, dull yellowish-orange with green tips, scale-like, broadly triangular to semicircular, 1.4–1.6 mm long, 1.2–1.6 mm wide at the base, incurved, apiculate, outside slightly keeled; stamens 6, in two whorls, 3 stamens of outer whorl subsessile with very short filaments adnate to middle part of corolla cup, 3 stamens of inner whorl with thick, finely papillose filaments 1–1.2 mm long, 0.2–0.3 mm thick, adnate to the base of corolla cup, anthers oblong reniform, 0.4–0.5 mm long, 0.2–0.3 mm broad, dehiscing longitudinally along lateral margin; pistillode with 3 completely separate carpellodes, placed close to each other at the center of corolla bottom, each carpellode small, bottle-shaped, slightly oblique, about 0.2 mm long and 0.05–0.07 mm wide in basal part, each with only one abortive ovule. Pistillate flower not seen. Fruit spherical or broadly obovoid, white (from three carpels in each individual flower normally only one developing) 7–9 mm across, with one large seed; epicarp pure white, thin, glabrous and smooth, glossy, skin-like; mesocarp fleshy and juicy with few soft fibers; endocarp thin woody, deep brown, densely adpressed to the seed. Seed spherical, with narrow longitudinal lateral cavity (from adaxial side); endosperm of stony, pure white to light yellow, of marble texture. (L.V. Averyanov & N. Tien Hiep & P. Ke Loc, Rhapis vidalii, A New Papyrus-like Palm from Vietnam. 2006)A

Materials Examined

  • VIETNAM. N. Vietnam, Hoa Binh prov., Mai Chau distr., Van Mai municipality, Highway 7, 15 km post. Primary lowland, very dry broad-leaved forest on shale at lower elevation to rocky, karstic limestone outcrops with deep fissures, between points 20°35’26’’N 105°02’00’’E and 20°34’39’’N 105°02’23’’E at elev. about 300–350 m. Sympodial palm with single stem up to 1.5 m tall. Fruits white, fleshy. Among limestone rocky outcrops. Locally abundant. 12 December 2002, D. Harder, N.T. Hiep, L. Averyanov et al., DKH 8123. (holotype HN; isotype LE); along road between Van Mai and Thanh Hoa, approximately 2 km SW of Van Mai village around point 20°34’17’’N 105°01’58’’E at elev. 600–650m. Disturbed secondary and remnants of primary rather dry broad-leaved forest on upper ridge slopes on limestone and shale soils with large, anciently eroded marble-like crystalline limestone. Palm up to 2 m tall, forming small clumps, flowering and fruiting in light gaps in the canopy. Leaves deep green, buds green, flowers dull yelloworange, green at tip. Locally abundant. 13 December 2002, D.Harder, N.T. Hiep, L. Averyanov et al., DKH 8188. Thanh Hoa prov., Ba Thuoc distr., Co Lung municipality, territory of Pu Luong protected area, near Pu Luong village, 20°27’01’’N, 105°11’03’’E. Primary very dry evergreen broad-leaved forest with Burretiodendron hsienmu along tops of remnant karst limestone ridge at elev. 500–550 m a.s.l. Palm 0.5–1 m hg on rocky steep slope. Locally common. 13 April 2001, N.T. Hiep, L. Averyanov, N.T. Vinh, D.T. Doan, HAL 929; Khuyn village, around point 20°26’31’’N 105°14’55’’E. Primary evergreen seasonal broad-leaved lowland forest on slopes of crystalline marble-like highly eroded limestone ridge at elev. 300–400 m. Small shrub-like palm 0.5–1.2 m tall. Occasional. 18 September 2003, L. Averyanov, D.T. Doan, J. Regalado, N.T. Vinh, HAL 3075. Quan Hoa Distr., Phu Le Municipality, Hang village, around point 20°31’33’’N, 105°05’06’’E. Secondary and primary closed evergreen seasonal broadleaved lowland forest on steep slopes of rocky ridge composed with crystalline marble-like highly eroded limestone at elev. 350–450 m. Palm 1–1.5 m tall on steep slope. Not common. 29 September 2003, L. Averyanov, P.K. Loc, D.T. Doan, N.T. Vinh, HAL 3559. Around point 20°32’29’’N, 105°04’32’’E. Primary closed evergreen seasonal broadleaved submontane forest on very steep slopes and cliffs of rocky ridge composed with crystalline marble-like highly eroded limestone at elev. 700–800 m. Palm up to 1.5 m tall. Very common. Co-dominant of herb forest stratum, 4 October 2003, L. Averyanov, P.K. Loc, D.T. Doan, N.T. Vinh, HAL 3899. (L.V. Averyanov & N. Tien Hiep & P. Ke Loc, Rhapis vidalii, A New Papyrus-like Palm from Vietnam. 2006)A