Polygonatum annamense A.Floden, 2015

Floden, Aaron J., 2015, A new Polygonatum (Asparagaceae) endemic to the Trư ờng Sơn of southern Vietnam, Phytotaxa 197 (2), pp. 125-131 : 126-130

Polygonatum annamense A.Floden , sp. nov.

Similar to Polygonatum punctatum Royle ex Kunth , but differs in its leaves borne in several whorls, in addition to spirally alternate and opposite at the apex; its white, emaculate and larger perigone, shorter smooth filaments, and terete stem.

Type:— VIETNAM. Kontum Province: Evergreen subcloud primary forest on NE slope of Ngoc Linh mountain system at 2200 m alt. Herb with stem up to 1.5 m high, sometimes epiphyte. Flowers whitish, fruits red, 24 March 1995, L. Averyanov, et al. VH 939 (holotype P!).

Plant perennial. Rhizome moniliform to torulose, 1–2 cm diam. Stem 30–80(–150) cm, red maculate, cataphylls 2–3, 1 cauline cataphyll, membranous, red maculate. Leaves alternate below, alternate, whorled, sub-verticillate to opposite above; elliptic-lanceolate to lanceolate-oblong, 6–15 × 1–4 cm, apex abruptly acuminate, obtuse, glabrous, glossy, base attenuate to a pseudopetiole, whitish, red maculate abaxially, 2–4 mm, 5–7 veins prominent. Inflorescence 1/ leaf, axillary, 1–3-flowered, erect to horizontal; peduncle 0.5–1.5 cm, red maculate, pedicel ca. 0.5 cm, red maculate, bracteoles subulate, caducous, ca. 2 mm long. Flowers: perigone white, cylindric, 9–12 mm long, lobes green, 3–4 mm long, filaments inserted just above middle, 0.8–1.1 mm long, tapered downward, glabrous, anthers 1.3–2 mm long, ovary 2.8–3.1 mm long, style 2.5–2.8 mm long, stigma barely trilobed. Fruit red, 4–8 mm diameter.

Phenology:—Flowering April–May, Fruiting September–October, fruits persisting until flowering.

Etymology:—The specific epithet is for the Annamite Mountain ecoregion which includes the Central Highlands of Vietnam and the southern Đà Lạt Plateau, part of Laos and Cambodia. In Vietnam these are known as the Trường SƠn and in Laos, the Sai Phou Louang.

Distribution:—This species only occurs in the upper elevation cloud forests of the Đà Lạt and Kon Tum Plateaus. It is known from Lâm Đồng and Kon Tum Provinces. One collection was from Ta Dung Mountain on the border of Lâm Đồng Province, but potentially in Đắk Lắk Province. It is likely that it occurs in Đắk Nông, Gia Lai, and Quảng Nam provinces. It should be sought in adjacent Laos (Xekong and Attopu provinces) where elevations support subtropical montane broadleaved evergreen forests between elevations of 1600–2100 m. A checklist of the flora of Laos PDR only includes P. kingianum Collett & Hemsley (1890: 138) ( Newman et al. 2007), though an undetermined Kerr collection (image BM!) was collected on Phu Bia, the highest mountain in Laos.

Additional specimens examined (paratypes):— VIETNAM. Đắk L ắk Province: Ta Dung, 1600m, 17 February 1953, M. Schmid VN 1614 ( P!) ; Lâm Đ ồng Province: Lac Duong Distr., Lat Commune , Nui Ba ( Lang Bian mountain ) 12.05N, 108.44E. 1950m, 9 November 2006, S. G. Wu, P. K. Loc, J. Y. Xiang, S. D. Zhang, N. V. Duy & N. T. Vinh WP-1489 ( MO!) ; 29 km to NE from Đà L ạt City, distr. Lac Duong, municipality Da Chay. Primary wet closed broad-leaved cloud forest along main Bi Dup ridge, 12.10N, 108.65E, 1900–2100m, 22 March 1997, L. Averyanov et al. VH3066 ( MO!) ; Đà L ạt, Tixien N34 , S 259 , 1957 ( P) ; Mt. Lang Biang. Đà L ạt. 1900m, 3 May 1964, M. Schmid s.n., ( P!) ; M Lang Biang, Đà L ạt, 1700m, (271h15h), M. Schmid s.n. ( P!) ; Massif du Bi-Daup, 14 October 1940, Poilane 30911 ( P!) ; 29 km to NE from Đà L ạt City, Dist. Lac Duong , munic. Da Chay. Primary wet closed broad-leaved cloud forest along main Bi Dup ridge at 1900–2100 m. alt., 12.1, 108.483333, 22 March 1997, L. Averyanov, N. Q. Binh, P. K. Loc VH 3066 ( MO!) ; Kon Tum Province: NW slopes of Ngoc Linh mountain system, near Ngoc Linh village , 1200–2500 m, 23 February 1995, L. Averyanov, et al VH 084 ( MO!) .

Taxonomic relationships:—Morphology of Polygonatum annamense including: 1) the distinctly tapered filaments with a gibbous protrusion at the attachment of the anther; 2) urceolate perigone shape; 3) rhizome and root type; 4) phyllotaxy; 5) maculation of the stems and leaves; and 6) molecular data (unpublished data) suggest a closer relationship to its geographically more distant sister species, P. punctatum , than it shares with either P. mengtzense or P. urceolatum from northern Vietnam and southwest China. Comparisons of P. annamense to P. punctatum , which are more similar to one another, are discussed herein while the differences between these two and P. mengtzense and P. urceolatum are presented below ( Table 1). Distinguishing features of Polygonatum annamense that separate it from P. punctatum are its overall larger plant size, terete stems, occasionally whorled leaves throughout the stem, rather than whorled only at the stem apex, and larger, emaculate, and non-urceolate flowers. Stem characters from my observations in this group of Polygonatum species show significant differences between the species without much variation within a species. All specimens of P. annamense observed and the single cultivated accession shows that the stem is terete throughout and, like many of the species in this group, maculate, at least in the proximal portion. In contrast, P. punctatum is prominently sulcate and papillose on the ridges. Phyllotaxy within this group provides some means of separation; P. annamense and P. punctatum have a mix of alternate leaves borne spirally around the stem, opposite leaves, and sometimes whorls whereas P. mengtzense and P. urceolatum are distinctly alternate and distichous on arching stems. In P. annamense and P. punctatum the leaves are mostly spirally alternate, but P. annamense has leaves in whorls of three on the lower part of the stem, alternate through the middle with an occasional opposite pair and usually terminated by an opposite pair, whereas P. punctatum has leaves alternate to opposite along the stem and usually terminally 3- whorled. Both have leaves that are elliptic to lanceolate with reddish maculate spots abaxially and are chartaceous to subcoriaceous in texture. The morphology of the inflorescence and their position on the stem is variable between P. annamense and P. punctatum . Polygonatum annamense has inflorescences that are one to four flowered with no tendency to produce fascicles thus far noted. Polygonatum punctatum has inflorescences sometimes in fascicles with several one-flowered pedicels or frequently with a one-flowered pedicel and often a twinned peduncle. Differences observable in the perigone morphology between Polygonatum annamense and P. punctatum are the insertion level and filament shape. The perigone of the former is larger (10–12 vs. 7–10 mm long), cylindric and not distinctly urceolate, with longer non-reflexed lobes, and without pink maculation always seen in P. punctatum . The insertion of the filaments within the perigone tube is near the middle in P. annamense and distal of the middle in P. punctatum . The shape of the filaments in both species are tapered with a distinct gibbous protrusion at the anther attachment, but the filaments in P. annamense are thicker, the taper less pronounced, smooth, and with a smaller, smooth gibbous protrusion while those of P. punctatum are more slender with a prominent gibbose protrusion that is papillose.

punctatum , and P. urceolatum . Morphological data measured from both specimens and cultivated material. All measurements are in millimeters.

The description of this new species endemic to the Central Highlands of Vietnam increases the number of species to four in this group of Polygonatum . All the species of this group are distributed from the Himalaya south and east into floristically Sino-Himalayan zones as defined by elevation in otherwise Sino-Japanese or Malayan floristic regions ( Averyanov et al. 2003). Polygonatum annamense represents an additional Sino-Himalayan floristic element of the Ngoc Linh Mountain area and the Đà Lạt Plateau. Both are areas of elevated floral endemism and also an intersection of the Sino-Himalayan and Malayan floristic provinces, the former found mostly at upper elevations ( Sterling & Hurley 2005, Le et al. 1999).